Petroleum Microbiology

The massive exploitation of the Orinoco Oil Belt (OOB), the largest proven reserves of unconventional oil in the world, generates large amounts of drilling wastes that must be managed properly. The aim of this study was to characterize molecularly and functionally the cultivable bacterial community present in drilling wastes mixed with water based drilling fluid of the OOB, to identify potential biocatalysts to be used in bioremediation processes. Eighty-eight bacterial strains were isolated and the morphological and biochemical characterization was initially performed, differentiating their functional activity by cluster analysis. Morphological descriptions revealed that 100% bacteria studied were gram-negative and 71.25% were cocci-bacilli. Biochemistry and functional analysis identified 66 functional groups and 14 groups of functional identity. Molecular studies using the DNA fingerprinting technique indicated the existence of 14 different genotypic groups of bacteria with high hydrocarburoclastic ability and biosurfactants production, which were molecularly identified. The results revealed that the bacteria belong to five (5) different genera: Enterobacter (6; 50%); Pantoea (2; 14,29%); Citrobacter (2; 14,29%); Klebsiella (2; 14,29%) and; Comamonas (1; 7,14%), 92.86% of which correspond to the Enterobacteriaceae family, gamma-proteobacteria class, frequently associated with environments contaminated with hydrocarbons. These bacterial strains were kept at the Bank of Microorganisms of the Department of Energy and Environment from IDEA to be used in future studies as potential biocatalyst in bioremediation process of drilling wastes generated by the oil industry.

B IOSURFACTANTS are active secondary metabolites producing` by certain microorganisms that have the ability to reduce surface and interfacial tension. They have numerous advantages, such as high biodegradability, increased foaming, low toxicity and performance under challenging conditions. Current study was compared between the potential production of biosurfactant by A. carneus OQ152507, A. niger OQ195934 and A. fumigatus OQ195264 using solid state fermentation (SSF) as a low-cost alternative technology. These isolates were cultivated under SSF using different eight agricultural wastes to produce biosurfactants. The optimized bioprocess conditions for the maximum biosurfactant productivity were potato peels waste (20g/l) as a carbon source at 35ºC and pH 7 in glucose peptone medium for A. carneus OQ152507, sun flower seed shells (28g/l) at 35ºC and pH 7 in starch nitrate medium for A. niger OQ195934 and tea wastes (20g/l) at 30ºC and pH 6 in glucose peptone medium for A. fumigatus OQ195264. Their stability was observed at 120°C, 30g/l of NaCl and alkaline pH 10 for A. carneus and pH9 for A. niger and A. fumigatus biosurfactants. The biosurfactants were identified as glycolipid and phospholipids molecules by Phenol-H 2 SO 4 and phosphate test. GC-MS and FT-IR analysis confirmed that the tested fungi participate in producing three hydrophobic fatty acid chains: Cis-Vaccenic acid, n-Hexadecanoic acid and Hexadecanoic acid 2-hydroxy-1 (hydroxymethyl) ethyl ester in distinct peaks with the highest percentage area. While, each one has at least one specific biosurfactant moiety.

El presente trabajo insertado dentro del subproyecto Misión Ciencia “Caracterización del Medio Físico Natural en Áreas Impactadas con Hidrocarburos, se propone caracterizar funcionalmente la comunidad bacteriana del suelo de la zona de descarga de la fosa Bare 9 para determinar la estructura funcional de la comunidad destacando grupos funcionales capaces de degradar sustratos complejos, crecer sobre hidrocarburos y producir biosurfactantes. En la zona de descarga se muestrearon 2 cuadratas (B9I y B9D), que presentaron derrame petrolero y 1 cuadrata en la zona con vegetación (B9V), se determinaron valores de abundancia del orden de 109 UFC/gr. de suelo en las zonas impactadas y 1012 UFC/gr. en la zona con vegetación. Las cepas se caracterizaron bioquímicamente, se utilizó el análisis multivariado de cluster para determinar la estructura funcional de la comunidad bacteriana se encontró un gran numero de cepas capaces de degradar glucosa (80%), de utilizar fuentes nitrogenadas el nitra...

Indoor and outdoor air of five (5) hospitals in Ilorin, Kwara state were sampled using settling plate method to isolate fifteen (15) bacteria. Bacillus cereus was the identified spore former. Biodegradation performance of Bacillus cereus on hexadecane and heptane using Mineral Salts Medium  (MSM) was studied for 20 days at four days interval using the Jenway 6320D Spectrophotometer to assess the optical density. The degradation and utilization of the hydrocarbons occurred before the fourth day with readings for optical density obtained as 1.051nm and 0.820nm for hexadecane and heptane respectively. After day 4, there was a sharp decline in the utilization of hydrocarbons. A second experiment was setup for optical density with heptane and decane utilization being checked daily for a period of 5days. Bacillus cereus utilized the hydrocarbons till the fourth day as the optical density dropped on the fifth day. The readings for decane obtained on day 4 and day 5 were 0.431nm and 0.338nm...

The bioremediation of modelled petroleum oil-contaminated soils of the Niger Delta by a mixed culture of three hydrocarbon-degrading bacteria, Acinetobacter sp, Rhodococcus sp and Pseudomonas sp, was investigated. These bacterial strains were selected based on criteria that they were able to utilize hydrocarbons (hexadecane and sodium benzoate) as the sole source of carbon and energy and were able to show significant growth in crude oil at an optimum temperature of 30 o C. For maximal bacterial growth and degradation effective aeration and agitation was required, thus the choice of the shake flask method over the bioscreen growth analyzer for this investigation. The influence of hexadecane concentrations (0.5%, 1.0% and 2.0%) on the bacterial isolates was investigated and it revealed that the Rhodococcus sp because of its different metabolic pathway showed a more rapid growth on hexadecane concentrations as compared Pseudomonas sp and Acinetobacter sp. Amongst the bacterial isolates, Pseudomonas sp exhibited a more rapid growth on 0.5% sodium benzoate while the two others showed minimal growth. Pseudomonas sp Rhodococcus sp and Acinetobacter sp showed a synergistic association when grown on basal salt medium supplemented with 1.0% w/v petroleum crude oil. The influences of a zeolite (clinoptilolite), soil structure and particle size on biodegradation of crude oil in modelled silt-clay and sandy soil of Niger Delta was investigated. Soils from the Hilton site, East-Shropshire, United Kingdom were used for the Niger Delta soils formulation. Geochemical properties of the soil samples from the x-ray fluorescence showed major elements are sodium, magnesium, aluminum, potassium, iron with silicon having high percentage, while x-ray diffraction analysis revealed minerals such as quartz, kaolinite, illite and smectite, which are similar to those of the Niger Delta. The preliminary investigation showed a more rapid and greater extent of apparent oil removal with the addition of both bacterial consortium and clinoptilolite on soil amendment experiments at 30 o C for a period of 30 days. There was 79% oil removal by the bacterial consortium in the soil amended with clinoptilolite as compared to 67% in the case of the amended soils without clinoptilolite. Although the addition of both bacterial consortium and clinoptilolite enhanced the removal of the crude oil, however the effect of clinoptilolite may be one of abiotic removal. The soil structure investigation without clinoptilolite augmentation showed that oil removal in the silt-clay soil was significantly greater than that of the sandy II soil after 30 days period (p< 0.0001). There was 72.7% ± 0.8% oil removal by the bacterial consortium in the silt-clay soil as compared to 55.6% ± 0.7% in the case of the sandy soil. However, there was 79.1% ± 0.4% oil removal by the bacterial consortium in the silt-clay soil amended with clinoptilolite as compared to 67.3% ± 0.8% in the case of the amended sandy soils with clinoptilolite. Gas chromatographic profile showed appreciable reductions in hydrocarbon, the rate of which depended upon the particular hydrocarbon. Quantitative analysis of residual oil extract from the silt-clay and sandy soil amended with and without zeolite showed a high rate of degradation for lighter hydrocarbon components (C 10-C 18) compared to the heavier ones (C 24-C 28) by the bacterial consortium. Hydrocarbon components (C 10-C 18) from both silty-clay and sandy soils amended with zeolite were degraded by the bacterial consortium to 92.1%-57.7% and 74%-43.7% respectively, while VI

This work was carried out in collaboration between all authors. Author OAO designed the study, performed the statistical analysis, wrote the protocol and wrote the first draft of the manuscript. Author JOO proofread the manuscript and gave technical inputs and author ATO managed the analyses of the study. Author ATO managed the literature searches while author EIA helped with interpretation of some of the data generated as well as proofreading the manuscript. All authors read and approved the final manuscript.

-In some areas of Ondo State, Nigeria, water resources are polluted by suspended oily solids, toxic metals and dissolved
petroleum hydrocarbons. Non-exploitation of the bitumen deposits in the areas for commercial purpose has aggravated the level
of pollution. The objective of this work was to develop a water decontamination facility for small-to- medium scale operation. A
Bitumen Polluted Water Treatment System (BPWTS) was designed and fabricated using acrylic glass (Perspex) material and
with appropriate facility for flow kinetics. The BPWTS comprised four columns for filtration and bioremediation. Processed
Chicken feather and African walnut (Plukenetia conophora) seed shells were biosorbents materials at stages 1 and 3, while stage
2 was for bioremediation with Pseudomonas aeruginosa as inoculum and stage 4 was for water discoloration using activated
charcoal. Bitumen-polluted water obtained from these affected streams and wells were run through the BPWTS and the pollution
removal efficiency (RE) was determined. Treated water at each stage was tested for turbidity, pH value, suspended solids, toxic
metals and dissolved petroleum hydrocarbon. Suspended solids reduced from 1.2 × 103 to 6.2 × 10 mg/L in stage 1, indicating
PCF’s good oleophilic properties. This prevented the bitumen solids from reaching other stages. At stage 2, Pseudomonas
aeruginosa reduced concentrations of lead (1.0 × 10−2 to 1.0 × 10−3 mg/L), benzene (3.7 to 2.5 µg/L), p-xylene (3.2 to 1.2 µg/L)
and o-xylene (3.2 to 1.2 µg/L). At stage 3, residual solids were removed and in stage 4 discoloration of water reduced from 15.60
to 0.98 Nephelometric Turbidity Units (NTU). Pollution indices of treated and untreated water samples were significantly
different. The RE of the BPWTS were 95.0% for suspended solids, zinc 82.0%, benzene 70.0%, o-xylene 65.0%, p-xylene 65.0%
and lead 62.0%, bringing the treated water to within permissible level for potable water. Decontamination technique developed
is able to minimize associated health risks in the area.

In some areas of Ondo State, Nigeria, water resources are polluted by suspended oily solids, toxic metals and dissolved petroleum hydrocarbons. Non-exploitation of the bitumen deposits in the areas for commercial purpose has aggravated the level of pollution. The objective of this work was to develop a water decontamination facility for small-to-medium scale operation. A Bitumen Polluted Water Treatment System (BPWTS) was designed and fabricated using acrylic glass (Perspex) material and with appropriate facility for flow kinetics. The BPWTS comprised four columns for filtration and bioremediation. Processed Chicken feather and African walnut (Plukenetia conophora) seed shells were biosorbents materials at stages 1 and 3, while stage 2 was for bioremediation with Pseudomonas aeruginosa as inoculum and stage 4 was for water discoloration using activated charcoal. Bitumen-polluted water obtained from these affected streams and wells were run through the BPWTS and the pollution removal efficiency (RE) was determined. Treated water at each stage was tested for turbidity, pH value, suspended solids, toxic metals and dissolved petroleum hydrocarbon. Suspended solids reduced from 1.2 × 10 3 to 6.2 × 10 mg/L in stage 1, indicating PCF's good oleophilic properties. This prevented the bitumen solids from reaching other stages. At stage 2, Pseudomonas aeruginosa reduced concentrations of lead (1.0 × 10 −2 to 1.0 × 10 −3 mg/L), benzene (3.7 to 2.5 µg/L), p-xylene (3.2 to 1.2 µg/L) and o-xylene (3.2 to 1.2 µg/L). At stage 3, residual solids were removed and in stage 4 discoloration of water reduced from 15.60 to 0.98 Nephelometric Turbidity Units (NTU). Pollution indices of treated and untreated water samples were significantly different. The RE of the BPWTS were 95.0% for suspended solids, zinc 82.0%, benzene 70.0%, o-xylene 65.0%, p-xylene 65.0% and lead 62.0%, bringing the treated water to within permissible level for potable water. Decontamination technique developed is able to minimize associated health risks in the area.

Souring in oil fields occurs mainly due to the activity of sulfate reducing bacteria (SRB). Most of the studies on SRB are performed using upflow packed-bed reactors that have a limitation to describe the region close to the injection wells in oil fields, which is characterized by void and saturated porous bed regions. Here, it is described the design and operation of a pilot scale system to investigate the SRB activity, inhibition and control in oil fields. The bioreactor is composed by two-compartments (empty and packed-bed). The reactor system has two parallel bioreactors that can be supplied with the same source of nutrients through a single pump or can be supplied separately with different solutions using two pumps. The hydrodynamics for conventional packed bed bioreactors has a mixing behavior dependent of the flow rate and has a significant bypass. In contrast, the two-compartment system presented here has a mixing behavior almost independent of the flow rate.

Background: With increasing demands of fossil fuel energy, extensive exploration of natural sources has caused a number of large scale accidental spills of crude oil and resulted in environmental disasters. The consequence of oil pollution to environment and human health has brought a serious challenge to environmental scientists. The aim of the present study is to evaluate the biodegradation of petrolum compound by Bacillus subtilis isolated from automobile workshops. Methods: Soil samples were collected from petrol bunks and workshops and subjected to serial dilution and plating. From the developed bacterial colonies, one was selected and identified as Bacillus subtilis based on the biochemical tests. The isolated strain was able to grow in minimal broth along with 2.5, 5, 7.5 and 10% concentrations of petrol which indicated the capability of the organism in degrading petrol and utilizing it as a source for growth. Results: The isolated strain's efficiency was determined by analysing the parameters pH, optical density and CO 2 released during petrol degradation. HPLC analysis also confirmed the degradation of petrol by Bacillus subtilis. Conclusion: The isolate Bacillus subtilis has the ability to tolerate the petrol concentrations and grow on them. Hence, this strain can be used in cleaning oil polluted sites.

A mixed consortium was prepared with 15 bacteria isolated by enrichment technique from the sample collected from an oil contaminated site. This consortium was incubated with crude oil to investigate the metabolic capability of bacteria. The degradation efficiency of the isolates in consortium was checked with 2% crude oil by shake flask transformation in mineral salt medium, at 37°C for 24 days. Total removal of aliphatic and aromatics was 94.64% and 93.75% respectively. Among the various components of the crude oil degradation by the bacterial consortium, the biotic removal of alkanes was maximum, 90.96% for tridecane (C 13) followed by pentadecane (C 15) at 77.95%, octadecane (C 18) at 74.1%, while other alkanes showed 56 to 69% after 24 days of incubation. The aromatics (benzene, toluene and xylene) were vaporized in the 4th day of incubation, while the efficiency on polyaromatic fractions (anthracene, phenanthrene and pyrene) was 46.17 to 55.3% after 24 days. The ability of degrading long chain n-alkanes and crude oil at high concentrations makes the consortium potentially useful for bioremediation and microbial enhanced oil recovery.

Conventional chemical surfactants applications usually linked with environmental unfriendliness and toxicity are associated with high production costs resulting from fluctuations in oil prices and thermal energy requirements. Sophorolipid biosurfactants can potentially be implemented with a remarkably low operating cost. Besides economic interest, sophorolipids and their derivatives have shown promise as emulsifiers, antimicrobials, surfactants and a source of specialty chemicals

Recently, has been studied the isolation of crude oil tolerant microorganisms and his capacity of degradation of crude oil in contaminated soils, such bacteria, yeast and fungi. Therefore, in this work, we isolate different microorganisms, which grow in presence of petroleum as the sole carbon source and we determined the activity of alcohol oxidase by a colorimetric method, in different cell fractions. Bacteria found were Serratia marcescens, Pseudomonas aeruginosa, Enterobacter aerogenes and Escherichia coli, the yeast, Candida albicans, and the fungi Aspergillus niger. In addition, they have good activity of alcohol oxidase in the cytosolic fraction with different substrates. It was concluded that this microorganisms could be used for decontamination of aquatic habitats polluted with petroleum. Keywords— Isolation, Microorganisms, Crude oil, alcohol oxidase,

Environmental pollution by crude oil can occur naturally through seepage or from anthropogenic sources via spillage, accidents or improper disposal of crude oil and related products. The main characteristic of pollution from refinery and petrochemical plants consists in that the pollution source is active, most often for a short period of time, but has an important intensity, polluting agent consisting generally of petroleum fractions. Also, in most cases of accidental spills of petroleum products, surface soil affected is much smaller than the first surface polluted aquifer pollution front met. Recent research has shown that biological methods to remediate crude oil polluted soil are a superior effective and much cheaper method compared with physicochemical methods. Biological methods are based on the activity of microorganisms to use crude oil as a source of carbon and energy. These methods are considered to be the most effective because it does not have irreversible effects on so...

The isolation of aerobic marine bacteria able to degrade hydrocarbons represents a promising alternative for the decontamination of oceanic and coastal environments. In the present work, twelve water and sediment samples from the Felton coastline in the Province of Holguín were collected and screened with Bushnell-Haas medium supplemented with light crude oil or with seawater supplemented with yeast extract and crude oil as a carbon source, obtaining twenty seven and six bacterial isolates respectively that were able to grow in these media. The obtained isolates were then subjected to selection in Bushnell-Haas medium supplemented with a heavy crude oil, selecting three strains able to degrade this hydrocarbon mixture within a period of seven days. Pure cultures of these strains were further used in crude oil biodegradability assays. Total petroleum hydrocarbon (TPH) degradation was evaluated through SARA analysis, employing gas chromatography with an FID detector and infrared spectroscopy to analyze the aliphatic and aromatic hydrocarbon fractions, respectively. All three stains removed more than 60% of the TPH and one of them showed the best degradation potential with figures above 65% for the entire hydrocarbon fraction, except resins. Two of the strains were also able to decrease C17:Pr and C18:Ph ratios to less than 50% in comparison to the abiotic control. Two of these strains were phenotypically identified as Bacillus sp., and the remaining one as Alcaligenes sp. The degradation potential exhibited by these new isolates warrants further studies on their possible application to decontaminate coastal environments affected by oil spills.

Hydrogen sulfide production by sulfate reducing bacteria (SRB) is the primary cause of oil reservoir souring. Amending environments with chlorate or perchlorate [collectively denoted (per)chlorate] represents an emerging technology to prevent the onset of souring. Recent studies with perchlorate reducing bacteria (PRB) monocultures demonstrated that they have the innate capability to enzymatically oxidize sulfide, thus PRB may offer an effective means of reversing souring. (Per)chlorate may be effective by (i) direct toxicity to SRB; (ii) competitive exclusion of SRB by PRB; or (iii) reversal of souring through re-oxidation of sulfide by PRB. To determine if (per)chlorate could sweeten a soured column system and assign a quantitative value to each of the mechanisms we treated columns flooded with San Francisco bay water with temporally decreasing amounts (50, 25, and 12.5 mM) of (per)chlorate. Geochemistry and the microbial community structure were monitored and a reactive transport...

El presente trabajo insertado dentro del subproyecto Misión Ciencia “Caracterización del Medio Físico Natural en Áreas Impactadas con Hidrocarburos, se propone caracterizar funcionalmente la comunidad bacteriana del suelo de la zona de descarga de la fosa Bare 9 para determinar la estructura funcional de la comunidad destacando grupos funcionales capaces de degradar sustratos complejos, crecer sobre hidrocarburos y producir biosurfactantes. En la zona de descarga se muestrearon 2 cuadratas (B9I y B9D), que presentaron derrame petrolero y 1 cuadrata en la zona con vegetación (B9V), se determinaron valores de abundancia del orden de 109 UFC/gr. de suelo en las zonas impactadas y 1012 UFC/gr. en la zona con vegetación. Las cepas se caracterizaron bioquímicamente, se utilizó el análisis multivariado de cluster para determinar la estructura funcional de la comunidad bacteriana se encontró un gran numero de cepas capaces de degradar glucosa (80%), de utilizar fuentes nitrogenadas el nitra...

The use of plastic as a packaging has been increased in the market. Plastics was polymers that difficult to degrade in nature which to be a source of environmental damage. This study was conducted to see the potential of Pseudomonas aeruginosa UKM1011 and natural bacteria to degrade plastics using modified Winogradsky columns. The natural substrate used as soil, sand, and water were taken from Tasik Kejuruteraan UKM Bangi, Selangor. Modified Winogradsky columns using 600ml mineral bottles filled with 300 gr of soil or sand as a substrate and 300 ml of water mixed with medium salt as nutrients. The degradation process carried out for 60 days with parameters were the measurement of optical density (OD) at 600nm, pH conditions, and percent weight loss every 15 days. The results show P. aeruginosa were able to utilize plastics as the carbon source in modified Winogradsky column. The highest plastic degradation was black plastic on the sand substrate by the added P. Aeruginosa was 1.6684...

Anaerobic ammonium-oxidizing (anammox) process plays an important role in the nitrogen cycle of the worldwide anoxic and mesophilic habitats. Recently, the existence and activity of anammox bacteria have been detected in some thermophilic environments, but their existence in the geothermal subterranean oil reservoirs is still not reported. This study investigated the abundance, distribution and functional diversity of anammox bacteria in nine out of 17 high-temperature oil reservoirs by molecular ecology analysis. High concentration (5.31-39.2 mg l −1) of ammonium was detected in the production water from these oilfields with temperatures between 55°C and 75°C. Both 16S rRNA and hzo molecular biomarkers indicated the occurrence of anammox bacteria in nine out of 17 samples. Most of 16S rRNA gene phylotypes are closely related to the known anammox bacterial genera Candidatus Brocadia, Candidatus Kuenenia, Candidatus Scalindua, and Candi-datus Jettenia, while hzo gene phylotypes are closely related to the genera Candidatus Anammoxoglobus, Candidatus Kuenenia, Candidatus Scalindua, and Candidatus Jettenia. The total bacterial and anammox bacterial densities were 6.4±0.5×10 3 to 2.0±0.18×10 6 cells ml −1 and 6.6± 0.51×10 2 to 4.9±0.36×10 4 cell ml −1 , respectively. The cluster I of 16S rRNA gene sequences showed distant identity (<92%) to the known Candidatus Scalindua species, inferring this cluster of anammox bacteria to be a new species, and a tentative name Candidatus "Scalindua sinooilfield" was proposed. The results extended the existence of anammox bacteria to the high-temperature oil reservoirs.

Microbial control of caged populations of Zonocerus variegatus was carried out using indigenous fungal entomopathogens isolated from the grasshopper&#39;s cadaver. Bioassay response indicated a dose-dependent mortality coupled with drastic reduction in food consumption among spores infected grasshoppers. Lethal time (LT 50 ) of 4.6 days for 10 3 spores/ml and 3.8 days for 10 7 spores/ml of oil formulation of Beauveria bassiana were observed. While Metarhizium sp recorded LT 50 of 9.0 days and 2.8 days for 10 3 and 10 7 spores/ml, respectively. The results obtained were discussed in relation to use of the isolates in the control Z. variegates infestation in forest agro-ecosystem of south west, Nigeria. Key Words: Microbial control, entomopathogenic fungi, Beauveria bassiana, Zonoccrus variegatus, Metarhizium sp . African Journal of Biotechnology Vol.4(1) 2005:113-116

Background: Petroleum hydrocarbons are mix compounds and divided into four groups: Saturates, Aromatics, Resins and Asphalten. Among various phases of crude-oil, the alkanes with medium length chain are favorable substrates that rapidly degraded, although short-chain alkanes are very toxic and long-chain alkanes have low solubility in water that reduce its bioavailability and make resistant to biodegradation. Objectives: The main goal of this study is the isolation, molecular identification and degradation properties of hexadecane degrading bacteria from contaminated soils. Materials and Methods: In this research to isolate aliphatic degrading bacteria, sampling from hydrocarbon contaminated soil with of petroleum reservoirs regions, Tehran were performed. Alkane degrading bacteria were isolated by enrichment in Bushnel-Hass medium with hexadecane as sole source of carbon and energy. The isolated strains were identified by amplification of 16S rDNA gene and sequencing. Alkane hydroxylase gene (alk-B) was identified in all strains by PCR with specific primers. Results: Among 8 strains three strains with high growth rate on hexadecane selected for further study. These three selected strains identified as Stenotrophomonas maltophilia strain M2, S. maltophilia strain Q2 and Tsukamurella tyrosinosolvens strain Q3. In comparison to the other bacteria, these bacterial strains can degrade hexadecane 2 times more; with a high emulsification activity. Conclusions: The 2.5% concentration of hexadecane was the best concentration that supports the growth of these strains. Among these strain T. tyrosinosolvens strain Q3 was the best strain for biodegradation of hexadecane. Alk-B gene was identified in all strains.

Conventional chemical surfactants applications usually linked with environmental unfriendliness and toxicity are associated with high production costs resulting from fluctuations in oil prices and thermal energy requirements. Sophorolipid biosurfactants can potentially be implemented with a remarkably low operating cost. Besides economic interest, sophorolipids and their derivatives have shown promise as emulsifiers, antimicrobials, surfactants and a source of specialty chemicals Original Research Article

Insolubility challenges have reduced the efficiency and rate of environmental bioremediation of hydrophobic pollutants occurring in hydrocarbons, soil and water environments. As biosurfactants, sophorolipids possess the unique capacity of activity at the interface of immiscible liquids or solid-liquid phases, thus reducing surface and interfacial tensions through emulsification, dispersion, foaming and wetting, with advantages of stability, ecological acceptability and ability to be produced from renewable and cheaper substrates. In light of the above, this study was aimed at assessing the hydrocarbons emulsification and heavy metals detoxification efficiencies of sophorolipid biosurfactants produced from harvested mushrooms and yeasts isolated from a hydrocarbon contaminated site in Obohia, Abia State, Nigeria. Isolates were cultured on an optimized media fortified with agro-industrial waste substrates of rice bran and food industry waste oil as hydrophilic and hydrophobic sources ...

The study of the anaerobic activity of sulfate-reducing bacteria, which are frequently found in petroleum fields, can be performed in upflow packed-bed bioreactors, which have been widely used in biotechnology due to the reduced bioreaction time and large surface area available for attachment of microorganisms. The solution residence time in these bioreactors strongly affects their performance due to biofilm adhesion and detachment rates and the liquid-biofilm mass transfer resistance. Therefore, a description of the solution hydrodynamic behavior of bioreactors is essential in accurate systematic analysis or mathematical modeling of such equipments. The flow behavior of the liquid phase of a bench-scale upflow packed-bed bioreactor filled with glass beads is studied using tracer experiments. The residence time distributions are calculated and interpreted. The results for different flow rates show curves with similar pattern, a peak at the beginning and a long tail that is distorted by the solution flow rate. At high flow rates the reactor behaves as a plug-flow that was distorted by the presence of small axial dispersion and an interaction with a stagnant zone. At low flow rates both the dispersion and the interaction with a stagnant zone are strong. At low and intermediate flow rates, one remarks a peak at the beginning of the curve, which indicates the presence of a bypass .

Background: Biosurfactants are produced extracellularly by microorganism on cell surface or extracellularly on media environments. They are known for their role in surface and interfacial tension reduction between molecules at the surface and interface, respectively. Thus, this study was conducted to determine and compare the capability of biosurfactant production from immediate agrochemical wastes (yam, cassava and sweet potato peels) using fungal isolates. Materials and Method: The test fungi (Aspergillus niger and Fusarium oxysporum) were isolated from yam, potato and cassava peels showing advanced rottenness. Standardized production of biosurfactants using well researched protocol involving media and inclusion of agrochemical wastes in a fermentation broth containing the isolated fungi was carried out. Results and Discussion: The highest biosurfactant activity value obtained was with F. oxsporum on yam peels with emulsi cation index (EI) of 94.2±0.20% on kerosene after 72 hours (EI72). While the lowest activity of biosurfactant was observed in A. niger grown on cassava peels broth with EI72 activity of 36.36±0.53% on diesel. The trend showed that emulsi cation index on diesel after 24 hours (E24) with biosurfactant from A. niger grown in yam peel broth gave the highest EI concentration (48.42±0.14%) followed by biosurfactant from F. oxysporum cultured in yam peels (48.27±0.99%). In comparison with kerosene emulsion formed: biosurfactant from F. oxysporum grown in yam peels showed highest EI (94±0.10%) followed by A. niger cultured in yam peels (78.72±1.08). The EI results showed that yam peel served as a better substrate for biosurfactant production while F. oxysporum is the better biosurfactant producing fungi. The EI values were slightly maintained for 48hrs (EI48) and 72hrs (EI72). The result of the oil spreading assay using engine oil revealed that biosurfactants produced by F. oxysporum grown on sweet potato peels broth displaced more area of expired engine oil in water by forming miscelles with oil displacement area (ODA) of 9.08±0.02cm 2 followed by biosurfactant from A. niger grown in sweet potato broth with ODA of 8.04±0.38 cm 2. In terms of substrate speci city the sequence of increment in EI was: Yam>Cassava>Sweet potato. However, considering the critical micellar level or the oil displacement ability of the product, the sequential increment was: Sweet potato>Cassava>Yam peels. Conclusion: The biosurfactant produced shows more cleansing ability towards kerosene than it does for diesel. Conversely, it could be channelled toward clean-up of kerosene viz a-viz crude oil contaminated surfaces and environment.

Background: Water plays an essential role in supporting life on earth and sea worldwide, requiringclean, safe, high quality and sustainable resources. Nowadays, many water resources have been contaminatedwith toxic compounds originating from petroleumdue to economical and industrial developments. There is anurgent need to clean up the waters with environmentally friendlyand inexpensive methods. This study investigated the biodegradation of total petroleum hydrocarbons (TPH) using Pseudomonas aeruginosa (P. aeruginosa) in southern Caspian Sea coastline. Methods: Coastline sediment samples were collected, with P. aeruginosa being the predominant strain. The bacteria were cultured in triplicates in the presence of 0.5, 1, 2 and 4% of gasoline andunder specific experimental conditions of varying temperature, pH, salinity, shaker speed, and incubation periods. The data representing the gasoline biodegradation in the samples were statistically analyzed. Results: At optimized experimental ...

}Measurements of electrical conductivity were obtained during treatment of acid mine drainage (AMD) by sulphate-reducing bacteria (SRB) in fed-batch column reactors. The advantages of this method are that it is non-invasive, non-destructive, and rapid, giving real-time information. Conductivity measurements were taken on an hourly basis throughout the course of several experiments in which the SRB were exposed to different quantities of fresh AMD. Simultaneous measurements were taken in a column in which no SRB were present but were also exposed to the same volumes of fresh AMD. As treatment of the AMD progressed, increases in conductivity were measured, generally localized to two regions in the gravel bed: the top and bottom 10 cm (4 00). Changes in conductivity were not always coincident with changes in ORP and pH, indicating that conductivity may be a more sensitive tool for locating and monitoring specific zones of SRB activity.

Bio-surfactants produced by bacteria are surface-active compounds required in the degradation of hydrocarbons. They are complex groups of surface-active molecules produced by microorganisms that stick to the specific cell covering or are secreted extracellularly in the growth medium. This study is aimed at determining the bio-surfactant-producing abilities of bacteria that are isolated from bitumen-polluted soil. Isolation of bacteria from bitumen-polluted soil samples was carried out using standard methods. The bio-surfactant producing ability of the isolated bacteria was investigated by several assays, including drop collapse test, tilting glass slide test, emulsification index, and foaming activity. Characterization of the isolated bacteria was carried out using 16S rRNA, and the extracted genome from each isolate was sequenced, showing the gene annotation of the isolates. Crystal violet biofilm analysis was carried out to determine the biofilm-producing ability of the isolated b...

Engine oil is complex mixture of hydrocarbons and organic compounds used to lubricate parts car engine so the engine works smoothly. After the usage period the oil as a lubricant ends, then the oil will be used more metals and polycyclic aromatic hydrocarbons (PAH). One friendly way environment is by bioremediation, namely biodegradation of pollutant compounds become simpler products and harmless. So far, research on contamination of hydrocarbon compounds especially used oil in fishing ports is still rarely done, especially with the addition of exogenous bacteria. This study aims to analyze the ability of the bacterium Pseudomonas aeuriginosa, Rhodococcus erythropolis and the combination of both in the bioremediation process of used oil hydrocarbons and determine the best bacterial formulations to degrade hydrocarbons from used oil waste. The method used in this research is the experimental method. Significant reduction results occurred in the treatment of combined Pseudomonas aeruginosa and Rhodococcus erythopolis with concentrations of used oil 30 ppm by 70% with the value of used oil concentration of 9 ppm, then in the treatment of Rhodococcus erythopolis with 45 ppm concentration of used oil there was a percentage the lowest decrease of 22% with the value of used oil final concentration of 35 ppm. If referring to the Regulation of the Minister of Environment No. 19 of 2010 that bioremediation of used oil waste using a combination of Pseudomonas aeruginosa and Rhodococcus erythopolis can produce final value pollutants that are still allowed for the harbor's aquatic environment.

Microbial control of caged populations of Zonocerus variegatus was carried out using indigenous fungal entomopathogens isolated from the grasshopper's cadaver. Bioassay response indicated a dose-dependent mortality coupled with drastic reduction in food consumption among spores infected grasshoppers. Lethal time (LT 50) of 4.6 days for 10 3 spores/ml and 3.8 days for 10 7 spores/ml of oil formulation of Beauveria bassiana were observed. While Metarhizium sp recorded LT 50 of 9.0 days and 2.8 days for 10 3 and 10 7 spores/ml, respectively. The results obtained were discussed in relation to use of the isolates in the control Z. variegatus infestation in forest agro-ecosystem of south west, Nigeria.

Spillage of furnace oil is a more frequent event in recent times. In this study, environmental samples from furnace oil spillage sites of the Shela River, the Sundarbans, Bangladesh, were collected after three weeks of spillage. Serial dilution was applied and total seven bacterial isolates were separated as pure cultures. The oil-degrading potentiality of all seven isolates was further assessed, confirmed and compared with the growth pattern in furnace oil supplemented media, 2, 6-dichlorophenolindophenol test, and gravimetric analysis. After 7 days of incubation, isolates SS 3 , RW 2 , and SB degraded 56%, 43%, and 52% of supplemented furnace oil, respectively. The top three hydrocarbonoclastic bacterial isolates were selected as potential and identified as Pseudomonas aeruginosa (SS 3), Bacillus sp. (RW 2), and Serratia sp. (SB). All three isolates showed significant oil-degrading capacity compared to negative control, when incubated in sterile pond water supplemented with 2% furnace oil, suggesting them as potential bioremediation agents.

Sixty nine hydrocarbon utilizing bacteria isolated from selected crude oil contaminated sites of ONGC (Gujarat) were screened for biosurfactant producing potential. VSHUB005 showing 28.59 ± 0.50% emulsification index, 69.73 ± 0.53 mN/m surface tension and 90.46 ± 0.08% interfacial tension reduction was considered as potential biosurfactant producer using primary (hemolytic activity and CTAB agar plate method) secondary (drop collapse, oil spread, emulsification index and surface tension) and tertiary (interfacial tension) screening methods. Very strong, negative correlation between surface tension measurement and interfacial tension reduction (rs= -0.961, AE = -1.000) was measured. VSHUB005 was identified as P. aeruginosa by 16S rDNA gene sequencing technique. The GenBank accession number for 16S rDNA sequence and NCIM culture deposition ID assigned are KC713611 and 5514, respectively

Sulphate-reducing bacteria (SRB) are microorganisms that can be used as removal agents in polluted water sources. The use of inorganic substrates in SRB systems could reduce the cost and simplify operation. However, the use of H2 as an energetic substrate and the production of H2S as a metabolic product could produce kinetic limitations. The aim of this study was to assess the extent to which the kinetics of a sulphate reduction bioreactor was limited by its gas transfer capacity. Reactor kinetics were monitored by total pressure kinetics without sulphate limitation. It was concluded that the bioreactor design should be based on transfer properties. The uptake rate of H2 reached a maximum of 10-4 M/min, equivalent to a sulphate reduction rate of 3.4 g·L-1·d-1. The hydrogen mass transfer rate required a kLa of 1.48 min-1 at 1.2·109 cells/L in order to avoid limitation by H2 bio-availability (1.23·10-9 L·min-1·cell-1), which is a relevant value for scaling-up purposes.

The use of plastic as a packaging has been increased in the market. Plastics was polymers that difficult to degrade in nature which to be a source of environmental damage. This study was conducted to see the potential of Pseudomonas aeruginosa UKM1011 and natural bacteria to degrade plastics using modified Winogradsky columns. The natural substrate used as soil, sand, and water were taken from Tasik Kejuruteraan UKM Bangi, Selangor. Modified Winogradsky columns using 600ml mineral bottles filled with 300 gr of soil or sand as a substrate and 300 ml of water mixed with medium salt as nutrients. The degradation process carried out for 60 days with parameters were the measurement of optical density (OD) at 600nm, pH conditions, and percent weight loss every 15 days. The results show P. aeruginosa were able to utilize plastics as the carbon source in modified Winogradsky column. The highest plastic degradation was black plastic on the sand substrate by the added P. Aeruginosa was 1.6684...

One of the major problems in the petroleum industry nowadays is crude oil spills. Riau Province, Sumatra is one of the largest oil producers in Indonesia. Accidental releases of petroleum products are of particular concern to the environment. The process of drilling and refining petroleum generates a large amount of oil sludge. One of the effective technologies used in the waste degradation process is bioremediation using certain microorganisms. The prime objective of the current research was to evaluate the efficiency of fungi consortiums in crude oil degradation in Bumi Siak Pusako-Pertamina Hulu, Indonesia. There are three potential fungi isolates as petroleum hydrocarbon degradation agents with four consortium variations. The parameter values of Optical Density (OD), pH, and diluted CO2 were measured on 0, 4, 8, and 16 days. To evaluate the fungal biodegradation activity using Gas Chromatography-Mass Spectrometry (GC-MS). The result showed that consortium II (KF II) has the highest potential to degrade petroleum hydrocarbon (50.61%). The visual GC-MS examination confirmed a decrease in the peak area for eight hydrocarbon compounds, indicating the efficiency of the fungi in the oil decomposition and dismantling of hydrocarbons. Our findings may provide new information on native fungal resources from chronically contaminated terrestrial environments, and will be useful for petroleum-contaminated bioremediation and other industrial applications.

Sixty nine hydrocarbon utilizing bacteria isolated from selected crude oil contaminated sites of ONGC (Gujarat) were screened for biosurfactant producing potential. VSHUB005 showing 28.59 ± 0.50% emulsification index, 69.73 ± 0.53 mN/m surface tension and 90.46 ± 0.08% interfacial tension reduction was considered as potential biosurfactant producer using primary (hemolytic activity and CTAB agar plate method) secondary (drop collapse, oil spread, emulsification index and surface tension) and tertiary (interfacial tension) screening methods. Very strong, negative correlation between surface tension measurement and interfacial tension reduction (rs= -0.961, AE = -1.000) was measured. VSHUB005 was identified as P. aeruginosa by 16S rDNA gene sequencing technique. The GenBank accession number for 16S rDNA sequence and NCIM culture deposition ID assigned are KC713611 and 5514, respectively

The method of storage is essential in maintaining water purity and safety for drinking purposes. This study assessed the effect of various storage containers on household drinking water quality in a resource-limited setting. A quasi-experimental design was adopted. Four communities using protected springs as household drinking water sources were purposively selected. Forty-four households were selected and randomly assigned to four treatment groups; namely Covered Buckets with Taps (CBT), Covered Buckets without Tap (CB), Covered Kegs with Taps (CKT) and Covered Kegs without Tap (CK). Physicochemical analysis and bacteriological analysis were carried out on the water samples before and after they were put in the containers. Data was analyzed using SPSS version 12. At baseline, mean pH values of water samples from the springs and RSC were 6.4±0.6 and 7.1±0.7 respectively which were above the recommended. Mean chloride concentration of springs (14.3±7.4mg/l) and RSC (19.3±10.0 mg/l) samples were below recommended. Mean Total Coliform Count (TCC) of the springs in the four communities was 18.0±4.0 and mean TCC of RSC was 12.7±4.9. Five percent of water samples from RSC had mean E.coli count of 100/100ml. The mean TCC after introducing CB, CBT, CK and CKT in all the communities were 10.0±4.0, 8.5±4.2, 6.9±2.8 and 7.3±3.7 respectively (p<0.05). The use of covered kegs without tap was best in reducing contaminants in drinking water. Education on appropriate household drinking water storage and handling practices is recommended.

Acid rock drainage from diffuse sources such as waste rock dumps, tailings impoundments and discard coal dumps represents a significant environmental risk to South Africa, particularly with respect to sulphate salinity. Passive or semi-passive remediation options may be more practical, sustainable and affordable in many cases. Where sulphate salinity is a concern, biological sulphate reduction (BSR) plays a key role. Widespread application of BSR has been constrained by the cost of the electron donor, process kinetics and management of the sulphide product. The system developed addresses the challenge of biomass retention by employing submerged carbon microfibers to provide a large surface area for microbial attachment. Electron donor for the sulphate reduction and sulphide oxidation is provided by the anaerobic degradation of complex organic carbon sources (eg grass, algae, manure) in a separate hydrolysis reactor. Finally, sulphide management is achieved through the partial oxidat...

Indoor and outdoor air of five (5) hospitals in Ilorin, Kwara state were sampled using settling plate method to isolate fifteen (15) bacteria. Bacillus cereus was the identified spore former. Biodegradation performance of Bacillus cereus on hexadecane and heptane using Mineral Salts Medium  (MSM) was studied for 20 days at four days interval using the Jenway 6320D Spectrophotometer to assess the optical density. The degradation and utilization of the hydrocarbons occurred before the fourth day with readings for optical density obtained as 1.051nm and 0.820nm for hexadecane and heptane respectively. After day 4, there was a sharp decline in the utilization of hydrocarbons. A second experiment was setup for optical density with heptane and decane utilization being checked daily for a period of 5days. Bacillus cereus utilized the hydrocarbons till the fourth day as the optical density dropped on the fifth day. The readings for decane obtained on day 4 and day 5 were 0.431nm and 0.338nm...

Microbial control of caged populations of Zonocerus variegatus was carried out using indigenous fungal entomopathogens isolated from the grasshopper's cadaver. Bioassay response indicated a dose-dependent mortality coupled with drastic reduction in food consumption among spores infected grasshoppers. Lethal time (LT 50) of 4.6 days for 10 3 spores/ml and 3.8 days for 10 7 spores/ml of oil formulation of Beauveria bassiana were observed. While Metarhizium sp recorded LT 50 of 9.0 days and 2.8 days for 10 3 and 10 7 spores/ml, respectively. The results obtained were discussed in relation to use of the isolates in the control Z. variegatus infestation in forest agro-ecosystem of south west, Nigeria.

Oil spills are always harmful, whether accidental or deliberate as it contains hydrocarbons which are carcinogenic and also cause great damage to marine ecosystem disturbing its food chain and hence a threat to entire marine community. Many chemical and physical methods are used to remove the spilled oil of ocean floor, each having some drawbacks. Bioremediation has a promising future in oil spill removal in which indigenous or exogenous microbes are used to clean the oil spill. These microbes are mostly fungi, bacteria, and yeasts, which are already present in the water. Otherwise not dividing actively, during spillage these proliferate quickly and eat up the hydrocarbons which are essential for their growth producing ultimate end products – carbon dioxide and water. Though not in abundance in marine ecosystem, fungi are found to be better degrader of hydrocarbon than other microbes, and its usage to clean up oil spills is burgeoning. This chapter generally emphasizes on marine fun...

Indoor and outdoor air of five (5) hospitals in Ilorin, Kwara state were sampled using settling plate method to isolate fifteen (15) bacteria. Bacillus cereus was the identified spore former. Biodegradation performance of Bacillus cereus on hexadecane and heptane using Mineral Salts Medium  (MSM) was studied for 20 days at four days interval using the Jenway 6320D Spectrophotometer to assess the optical density. The degradation and utilization of the hydrocarbons occurred before the fourth day with readings for optical density obtained as 1.051nm and 0.820nm for hexadecane and heptane respectively. After day 4, there was a sharp decline in the utilization of hydrocarbons. A second experiment was setup for optical density with heptane and decane utilization being checked daily for a period of 5days. Bacillus cereus utilized the hydrocarbons till the fourth day as the optical density dropped on the fifth day. The readings for decane obtained on day 4 and day 5 were 0.431nm and 0.338nm...

This work was carried out in collaboration between both authors. Author RRN designed the study. Author IMO performed the statistical analysis, wrote the protocol, wrote the first draft of the manuscript, managed the analyses of the study and managed the literature searches under the strict supervision of author RRN. Both authors read and approved the final manuscript.

Aim: The aim of this study is to enhance the biodegradation of degreasers used in upstream sectors of Nigeria Petroleum Industry using bio-augmenting organisms such as: Pseudomonas and Bacillus species in freshwater Ecosystem. Study Design: This study employs experimental designs, Randomized Block Design treatment set up, statistical analysis of data and interpretation. Place and Duration of Study: Freshwater sample for this research was collected from Asarama Andoni, in Rivers State, Nigeria. The study lasted for six months. Methodology: The experimental set-up was carried in 500 ml conical flask with two species of bacteria, two types of degreaser and fresh water sample giving a total of 8 set-up including controls. The Pseudomonas and Bacillus species used in this study were isolated from the freshwater ecosystem and identified using standard microbiological methods. The bioremediation potential of the respective test organisms were monitored at ambient temperature 28±0.2°C for 2...

Microbial sulfate reduction is a primary cause of oil reservoir souring. Here we show that amendment with chlorate or perchlorate [collectively (per)chlorate] potentially resolves this issue. Triplicate packed columns inoculated with marine sediment were flushed with coastal water amended with yeast extract and one of nitrate, chlorate, or perchlorate. Results showed that although sulfide production was dramatically reduced by all treatments, effluent sulfide was observed in the nitrate (10 mM) treatment after an initial inhibition period. In contrast, no effluent sulfide was observed with (per)chlorate (10 mM). Microbial community analyses indicated temporal community shifts and phylogenetic clustering by treatment. Nitrate addition stimulated Xanthomonadaceae and Rhizobiaceae growth, supporting their role in nitrate metabolism. (Per)chlorate showed distinct effects on microbial community structure compared with nitrate and resulted in a general suppression of the community relative to the untreated control combined with a significant decrease in sulfate reducing species abundance indicating specific toxicity. Furthermore, chlorate stimulated Pseudomonadaceae and Pseudoalteromonadaceae, members of which are known chlorate respirers, suggesting that chlorate may also control sulfidogenesis by biocompetitive exclusion of sulfate-reduction. Perchlorate addition stimulated Desulfobulbaceae and Desulfomonadaceae, which contain sulfide oxidizing and elemental sulfur-reducing species respectively, suggesting that effluent sulfide concentrations may be controlled through sulfur redox cycling in addition to toxicity and biocompetitive exclusion. Sulfur isotope analyses further support sulfur cycling in the columns, even when sulfide is not detected. This study indicates that (per)chlorate show great promise as inhibitors of sulfidogenesis in natural communities and provides insight into which organisms and respiratory processes are involved.

Molecular and culture-based methods were used to investigate the microbial diversity in produced water obtained from the high-temperature Troll oil formation in the North Sea. 16S rRNA gene libraries were generated from total community DNA, using universal archaeal or bacterial oligonucleotide primer sets. Sequence analysis of 88 clones in the bacterial library indicated that they originated from members of Firmicutes (48 sequences), Bacteroidetes (17 sequences), d-Proteobacteria (15 sequences), Spirochaetes (5 sequences), Thermotogales (2 sequences) and c-Proteobacteria (1 sequence). Twenty-two sequences in the archaeal library were close relatives to members of the genera Methanococcus (18 sequences), Methanolobus (3 sequences) and Thermococcus (1 sequence). Most of the bacterial sequences shared less than 95% identity with their closest match in GenBank, indicating that the produced water harbours a unique community of novel bacterial species or genera. Members of the thermophilic genera Thermosipho, Thermotoga, Anaerophaga and Thermovirga were isolated. The Troll formations are not injected with sea water. Thus, dramatic changes of the in situ conditions have been avoided, and a common source of continuous contamination from injection water can be excluded. However, the majority of the organisms detected in the gene libraries were most closely related to cultivated organisms with optimum temperatures for growth well below the in situ reservoir temperature (708C), indicating that produced water from the Troll platform harbours a substantial amount of non-indigenous organisms. This was confirmed by the isolation of a number of mesophilic and moderately thermophilic organisms that were unable to grow at reservoir temperature.

Biosurfactants are surface-active molecules synthesized by microorganisms which have both hydrophobic and hydrophilic domains and are capable of lowering the surface tension and the interfacial tension of the growth medium. They are more active and less toxic than the chemical surfactants which are more difficult to degrade from the environment. The aim of this study was to determine the biosurfactant activity of fungi: Candida tropicalis and Aspergillus clavatus isolated from oil polluted soil. C. tropicalis and A. clavatus were isolated from soil samples obtained from three automobile workshops at Old Motor Spare Parts, Nkpor, Nigeria, using the spread plate technique. They were identified using the standard methods and confirmed using 18S rRNA gene sequence. Biosurfactant activities of the isolates were determined using the emulsification index (E 24), oil spreading technique and microbial cell surface hydrophobicity in three different oils: used engine oil (UEO), diesel and petrol. Data were analyzed using analysis of variance (ANOVA) at P = 0.05. The biosurfactant activity of the isolates showed high emulsification index (> 50%), oil displacement area (ODA) (> 4.5 cm 2) and cell surface hydrophobicity (> 50%) in UEO, diesel and petrol. However, the E 24 of the isolates were significantly higher in petrol (P < 0.05) compared with UEO and diesel. The broth culture containing A. clavatus showed significantly higher ODA in petrol (P < 0.05) when compared with UEO and diesel. The isolates C. tropicalis and A. clavatus showed biosurfactant activity in UEO, diesel and petrol, thus have promising potential against different hydrocarbon pollution.

The massive exploitation of the Orinoco Oil Belt (OOB), the largest proven reserves of unconventional oil in the world, generates large amounts of drilling wastes that must be managed properly. The aim of this study was to characterize molecularly and functionally the cultivable bacterial community present in drilling wastes mixed with water based drilling fluid of the OOB, to identify potential biocatalysts to be used in bioremediation processes. Eighty-eight bacterial strains were isolated and the morphological and biochemical characterization was initially performed, differentiating their functional activity by cluster analysis. Morphological descriptions revealed that 100% bacteria studied were gram-negative and 71.25% were cocci-bacilli. Biochemistry and functional analysis identified 66 functional groups and 14 groups of functional identity. Molecular studies using the DNA fingerprinting technique indicated the existence of 14 different genotypic groups of bacteria with high hydrocarburoclastic ability and biosurfactants production, which were molecularly identified. The results revealed that the bacteria belong to five (5) different genera: Enterobacter (6; 50%); Pantoea (2; 14,29%); Citrobacter (2; 14,29%); Klebsiella (2; 14,29%) and; Comamonas (1; 7,14%), 92.86% of which correspond to the Enterobacteriaceae family, gamma-proteobacteria class, frequently associated with environments contaminated with hydrocarbons. These bacterial strains were kept at the Bank of Microorganisms of the Department of Energy and Environment from IDEA to be used in future studies as potential biocatalyst in bioremediation process of drilling wastes generated by the oil industry.

Two biofilm reactors, using pumice stone and Poraver as biofilm supports, were run, based on the optimization of sulphide production using a factorial design. The maximum H 2 S concentrations reached were 10 and 15 mM, respectively, both being appropriate for metal precipitation in effluents. The setup of the pumice stone biofilm reactor is suitable for application in the mining area in the Bolivian Andean region, where this material is widely available. The use of specific primers for sulphate-reducing bacteria groups permits the identification of the sulphide-producing bacteria present in biofilms.