Microbiology

Aims: Bacteriological quality assessment and antibiogram profile of bacteria associated with sachet drinking water was carried out with view to determine the bacterial load and fitness of the water sold in the study area for human consumption. Materials and Methods: Ten samples of different brands were aseptically collected and analyzed using heterotrophic count and most probable number technique. The isolated bacteria were microscopically and biochemically characterized and finally confirmed using Box™ Easygel® E. coli Quantitube™ Test Kit (Micrology Laboratories manufactures, Easygel®, USA) biotyping. Physicochemical analysis of the samples was done using standard methods. The isolated bacteria were screened for antimicrobial susceptibility using Kirby-Bauer disc diffusion technique. Results: The total heterotrophic bacterial count ranged from 1.0×10 2 to 3.0×10 2 cfu/ml, with MPN/100ml values ranged from <0.03 to 1.2. The temperature ranged from 8 to 18°C, at the pH range of 5.0 to 7.6. The findings showed that, high temperatures and pH was associated with high bacterial counts. There was no statistical relationship between microbial loads and the temperature (p= 0.454) of the analyzed sachet water. Also, there was no statistical relationship between microbial loads and pH (p= 0.446) of the sachet water. The bacteria isolated were Escherichia coli, Enterobacter aerogenes, Salmonella sp, Citrobacter freundii and Proteus vulgaris. Most 9 (90%) of the water analyzed fell within the statutory limits. While, the remaining 1 (10%) fell within the contamination level, which recorded high bacterial counts beyond the standard of safe drinking water set by water and food regulatory bodies. Conclusion: The isolation of E. coli and Salmonella sp. in sample brand "A" in this study is an indication that if not promptly checked, an outbreak could occur in the near future. All the isolates are susceptible to variety of antibiotics used, except Enterobacter aerogenes, Salmonella sp. and Citrobacter freundii which recorded resistance to amoxicillin, and Proteus vulgaris which recorded multidrug resistance.

One of the major impediments to the commercialization of biodegradable plastic is the high cost of substrate. Consequently, there is a continuous search for effective microorganisms and cheaper carbon substrates to reduce the high production cost. In this study, waste transformer oil-degrading bacteria were isolated from soil, wastewater, and sediment samples, using a mineral salt medium (MSM) supplemented with 1% waste transformer oil as the sole carbon source. The isolates were screened for polyhydroxyalkanoates (PHA) production using Nile red staining and fluorescence microscopy. PHA granules accumulation was confirmed using transmission electron microscopy. Oil degradation analysis was accomplished using solvent extraction and gravimetric methods whereas, the bacteria were identified using 16S DNA sequence homology. A total of 62 transformer oil-degrading bacteria were isolated, out of which 16 (26%) showed positive results for Nile red fluorescence microscopy. The identified or...

Metallothioneins are usually low molecular weight metal binding proteins which were first discovered in the late 1950&#39;s following an intensive study of yeast, mammals and plants. Among the four subfamilies or classes of plant metallothioneins, Type 4 plant metallothioneins (PMT&#39;s), metallothioneins 4 (MT4) or early cysteine as popularly known, stands out to be the most intensively studied group in vitro, perhaps this is attributed to their peculiar structure and function coupled with ease of isolation and purification when compared to other metallothioneins (MT&#39;s). In a recent study on barley (Hordeum vulgare) a member of this group revealed that MT4 genes of the plant show local zinc binding in the grain aleuronic layer and act in putative storage. However, structural information and understanding of metal binding dynamics of these MT&#39;s are scanty, with early cysteine metallothioneins (MT) from wheat as the only PMT with crystal 3D structure currently available. Thi...

In this research, the utilisation of used transformer oil (UTO) as carbon feedstock for the production of polyhydroxyalkanoate (PHA) was targeted; with a view to reducing the environmental challenges associated with the disposal of the used oil and provision of an alternative to non-biodegradable synthetic plastic. Acinetobacter sp. strain AAAID-1.5 is a PHA-producing bacterium recently isolated from a soil sample collected in Penang, Malaysia. The PHA-producing capability of this bacterium was assessed through laboratory experiments in a shake flask biosynthesis under controlled culture conditions. The effect of some biosynthesis factors on growth and polyhydroxyalkanoate (PHA) accumulation was also investigated, the structural composition of the PHA produced by the organism was established, and the characteristics of the polymer were determined using standard analytical methods. The results indicated that the bacteria could effectively utilise UTO and produce PHA up to 34% of its ...

Aims: Bacteriological quality assessment and antibiogram profile of bacteria associated with sachet drinking water was carried out with view to determine the bacterial load and fitness of the water sold in the study area for human consumption. Materials and Methods: Ten samples of different brands were aseptically collected and analyzed using heterotrophic count and most probable number technique. The isolated bacteria were microscopically and biochemically characterized and finally confirmed using Box™ Easygel® E. coli Quantitube™ Test Kit (Micrology Laboratories manufactures, Easygel®, USA) biotyping. Physicochemical analysis of the samples was done using standard methods. The isolated bacteria were screened for antimicrobial susceptibility using Kirby-Bauer disc diffusion technique. Results: The total heterotrophic bacterial count ranged from 1.0×102 to 3.0×102 cfu/ml, with MPN/100ml values ranged from &lt;0.03 to 1.2. The temperature ranged from 8 to 18°C, at the pH range of 5.0...

Polyethylene is the most commonly used synthetic plastic and poorly degraded in natural environments. This study was designed to evaluate biodegradation potentials of low-density polyethylene by fugal isolates from Station Market, Kaduna State, Nigeria. Soil samples were collected at a depth of 20cm using a sterilized hand towel and taken to microbiology laboratory, Kaduna State University. Fungi were isolated and each colony was repeatedly sub-cultured on freshly prepared SDA to obtain pure isolates. Pure separated single colonies were maintained on sterile slants at 4˚C for further investigation. Low-density polyethylene (LDPE) sheets were cut into bits and immersed in xylene and boiled for 15 minutes to dissolve and crushed. The LDPE powder was added to a mineral salt medium (MSM) containing salts in 1liter of distilled water after which the fungal isolates were introduced. Scanning electron microscopy and Fourier-Transform Infrared Spectroscopy (FTIR) analysis were used to determine the changes in the polymer bond of LDPE sheet after the biodegradation. The findings shows that Aspergillus niger, Aspergillus flavus, Brown rot and White rot fungi showed 21.1%, 16.1%, 17.6%, and 18.3% reductions in the polyethylene discs after incubation respective. Therefore, the study concludes that fungal species play a significant role in the degradation of LDPE and can be used in future studies for the degradation of complex plastic materials. Finally, the study recommends that Aspergillus niger and Aspergillus falvus be considered as potential candidates to degrade LDPE.

Antioxidative compounds play a vital role to inhibit the oxidation of oxidizable products and influences the body defense system against Reactive Oxygen Species (ROS), which are harmful byproducts engendered during normal aerobic cellular respiration. ROS are specialized class of highly reactive molecules that originates during oxygen metabolism, whereas extensive evidences indicate the involvement of ROS in the development of degenerative diseases in humans. Despite the fact that synthetic antioxidants such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are threat to human's health; they are widely employed as chemical preservatives to avert potential deterioration of food products. Several toxicological findings reveal that natural antioxidants are capable of providing protection against free radical-related diseases, cancer and other cardiovascular infections. In cognizance with these facts, natural antioxidant attracts a great deal of research interest; therefore, this review provides a comprehensive and an up-to-date overview of the three most essential natural plant antioxidants; their antioxidative properties, methods of analysis and evaluation. These Polyphenols comprise: Phenolic acid, an essential polyphenol that are broadly dispersed in plants to exert positive influence on oxidative stress; Flavonoid, an ubiquitous antioxidant that functions in free radical scavenging, metal ion chelation and enzymes inhibition to suppress the synthesis of free radicals; and Tannic acid, a water soluble anti-nutrient that acts to precipitate alkaloids & proteins, reduce mineral & vitamin utilization and restrict the activities of digestive enzymes. In conclusion, a variety of plant species were characterized to indicate in vitro antioxidative properties.

The conversion of waste obtained from agricultural processes into biocompatible materials (biomaterials) used in medical surgery is a strategy that will add more value in waste utilization. This strategy has successfully turned the rather untransformed wastes into high value products. Eggshell is an agricultural waste largely considered as useless and is discarded mostly because it contributes to pollution. This waste has potential for producing hydroxyapatite, a major component found in bone and teeth. Hydroxyapatite is an excellent material used in bone repair and tissue regeneration. The use of eggshell to generate hydroxyapatite will reduce the pollution effect of the waste and the subsequent conversion of the waste into a highly valuable product. In this paper, we reviewed the utilization of this agricultural waste (eggshell) in producing hydroxyapatite. The process of transforming eggshell into hydroxyapatite and nanohydroxyapatite is an environmentally friendly process. Eggsh...

Great advances have been made in the past five decades in understanding the molecular mechanics of the two-component signal transduction pathway in bacteria but its applications in Medicine and Food Industries are yet to be fully unravelled. We discuss the varying changes in the extracellular environment of bacteria and their possession of multiple Two-Component Systems with each being specialize to react to a specific environmental signal, such as pH, nutrient level, redox state, osmotic pressure, quorum signals, and antibiotics. The sensitivity of this response transmits information between different Two-Component Systems to form a complex signal transduction network. Bacteria's signal transduction system, referred to as a two-component system, are essential for adaptation to external stimuli. These systems provides a signal transduction pathways widely employed from prokaryotes to eukaryotes. Typically, each two-component system composed of a sensor protein distinctively monitors an external signal(s) and a response regulator (RR) that controls gene expression and other physiological activities which are collectively assembled in a signal transduction pathway. This annex reviews the molecular mechanics underlying the signal transduction systems in prokaryotic organisms. It is not uncommon to hear, either explicitly or implicitly, the statement that "two component regulatory systems are well understood". Therefore, we examine the current models of the mechanisms of the regulatory systems and provide viable suggestions to further expand its applications in drug efficiency and antibiotic resistance in humans as well as enhancing the shelf-life of products in the food industry. We also outline the challenges that might have quenched possible trials of this application to human health.

Sulfate-reducing bacteria are categories of bacteria and archaea that can obtain energy by oxidizing organic compounds or molecular hydrogen (H 2) while reducing sulfate (SO 4 2−) to hydrogen sulfide (H 2 S). By analysis, these organisms "respire" sulfate rather than oxygen, a form of anaerobic respiration, the oxidation of hydrogen by the primary genus of Sulfate Reducing Bacteria (Desulfovibrio, Desulfovibrio desulfuricans) is catalyzed by enzymes called Hydrogenases. Three basic types of hydrogenases have been widely isolated from the primary genus of sulfate-reducing bacteria Desulfobibrio which differ in their structural subunits, metal compositions, physico-chemical characteristics, amino acid sequences, immunological activities, structural gene configuration and their catalytic properties. Broadly, hydrogenases can be considered as 'iron containing hydrogenases and nickel-containing hydrogenases. The iron-sulfurcontaining hydrogenase enzyme contains two ferredoxin-type (4Fe-4S) clusters and typical iron-sulfur center believed to be involved in the activation of H 2 yet it is the most sensitive domain to CO and NO 2 − .eventhough it is not featured in all species of genus Desulfovibrio. The nickel-(iron-sulfur)-containing hydrogenases, [NiFe] hydrogenase posses two 4Fe-4S centers and one 3Fe-xS cluster in addition to nickel and have been found in all species of Desulfovibrio with strong resistance to CO and NO 2 so far investigated. The genes encoding the large and small subunits of a periplasmic and membrane-bound species of the [NiFe] hydrogenase have been cloned in Escherichia coli and sequenced, however the functional complexity of the hydrogenase system remained unexplored as a result of the metabolic diversity in Desulfovibrio spp. The [NiFe] hydrogenase plays an important role in the energy metabolism of Desulfovibrio spp. Thus, the expression of the encoded structural genes would be an excellent marker for the metabolic functionalities under specific inducible environment.

Quorum sensing (QS) plays a vital role in controlling virulence in bacterial species. Vibrio cholerae, the main causative agent of cholera uses chemical signals to control virulence and biofilm formation. QS Always depend on the secretion and detection of signaling molecules known as auto inducers. Contrary to other bacteria that cause virulence at High cell density (HCD) when they attain a specific threshold, reverse is the case for V. Cholerae. At Low cell density (LCD), activation in the expression of virulence gene by V. cholerae destabilizes HapR while stabilizing AphA. The activation of AphA structural genes result in the expression of CT and TCP virulence together with the formation of biofilm. At HCD, the coherence of the two quorum-sensing auto-inducers (CAI-1 and AI-2) represses the expression of the virulence genes by activating HapR which in turn synthesizes Hap protease that acts as a detachase to get rid of the virulence genes and biofilm formation. In this review, we outline the QS mechanism used by Vibrio cholerae to cause infection by the production of virulence factors. In addition, we examine how this infection can be minimize through the use of chemicals which act as either inhibitors or agonist to the QS system.

Aflatoxins are mycotoxins produced by fungi of the genus Aspergillus that contaminate food products such as cereals leading to serious health and economic consequences. In order to assess the level of fungal contaminants and the presence of aflatoxins in such products, five (5) different cereal samples comprising of rice, maize, millet, wheat and sorghum were purchased each from two major markets within Kaduna metropolis. The samples were assessed for fungal contaminants using ten-fold serial dilution and cultured appropriate dilutions using pour-plate technique. Aflatoxins were detected using Enzyme-linked Immunosorbent Assay (ELISA). The results obtained revealed viable fungal counts ranging from 3 x 102 to 3.2 x 103 cfu/g. The fungal contaminants identified from the samples include Aspergillus flavus, Aspergillus niger, and Aspergillus fumigatus. The aflatoxins detected from the samples were within the range of 0.3 to 0.6 part per billion (ppb) which is less than the maximum valu...

In marine environments where biofouling occurs and has an impact on the maritime economy and environment, compounds that inhibit the attachment, growth and survival of microorganisms in a biofilm complex as well as settlement of larvae are considered potential antifouling compounds. In this study, the extracellular metabolites from two surface- associated bacteria isolated from soft coral and macroalga were evaluated for antibiofilm and antisettlement activity. The bacteria were identified using 16S rRNA gene sequencing, and the culture supernatant extract of each strain was evaluated for antibiofilm activity. The compounds present in the extracts were analysed using GC-MS. The two bacterial strains were identified as Bacillus licheniformis MBR1 and Vibrio alginolyticus MBR4 for the isolates from soft coral and macroalgae, respectively. The extracts inhibited the growth of biofilm-forming bacteria, biofilm formation and barnacle larval settlement. The GC-MS analysis of the extract d...

The emergence of antibiotic-resistant bacterial pathogens, especially Gram-negative bacteria, has driven investigations into suppressing bacterial virulence via quorum sensing (QS) inhibition strategies instead of bactericidal and bacteriostatic approaches. Here, we investigated several bee products for potential compound(s) that exhibit significant QS inhibitory (QSI) properties at the phenotypic and molecular levels in Chromobacterium violaceum ATCC 12472 as a model organism. Manuka propolis produced the strongest violacein inhibition on C. violaceum lawn agar, while bee pollen had no detectable QSI activity and honey had bactericidal activity. Fractionated manuka propolis (pooled fraction 5 or PF5) exhibited the largest violacein inhibition zone (24.5 ± 2.5 mm) at 1 mg dry weight per disc. In C. violaceum liquid cultures, at least 450 lg/ml of manuka propolis PF5 completely inhibited violacein production. Gene expression studies of the vioABCDE operon, involved in violacein biosynthesis, showed significant (Ctwo-fold) down-regulation of vioA, vioD and vioE in response to manuka propolis PF5. A potential QSI compound identified in manuka propolis PF5 is a hydroxycinnamic acid-derivative, isoprenyl caffeate, with a [M-H] of 247. Complete violacein inhibition in C. violaceum liquid cultures was achieved with at least 50 lg/ml of commercial isoprenyl caffeate. In silico docking experiments suggest that isoprenyl caffeate may act as an inhibitor of the violacein biosynthetic pathway by acting as a competitor for the FAD-binding pockets of VioD and