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Katalin Perei

University of Szeged, Department of Biotechnology, Adjunct

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Name:Dr. Katalin PereiCitizenship:HungarianEmployment:Department of Biotechnology, University of SzegedKözép fasor 52. Szeged, Hungarymail: [email protected]:Assistant ProfessorRESEARCH INTERESTBiorefinery, Bioconversion, Metabolic pathways of recalcitrant, Bioremediation, Environmental biotechnology, Biofuels,

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University of Szeged

Peter Schröder

Helmholtz-Zentrum München

National Research Centre

Obeida Al-Hajali

Alessandro Vastolo

Università degli Studi di Napoli "Federico II"

Bismark Asante-Badu

Università degli Studi di Perugia

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Papers by Katalin Perei

Phytotoxicity evaluation of nutrient-fortified pomegranate peel powders prepared from food waste and their feasibility as biofertilizers

Environment, Development and Sustainability

Pomegranate peel powder (PPP) is increasingly used as a bioadsorbent to decontaminate wastewaters... more Pomegranate peel powder (PPP) is increasingly used as a bioadsorbent to decontaminate wastewaters due to its adsorptive characteristics. The application of nutrient-fortified bioadsorbents as alternatives to chemical fertilizers can provide an innovative and eco-friendly approach for sustainable waste management. Nevertheless, there is extremely limited information regarding their effects on the growth of agricultural crops. We investigated the effects of raw and nutrient-fortified PPPs on oilseed rape (Brassica napus). Our results showed that the concentration-dependent in vitro phytotoxicity of high PPP doses (germination indices were 109.6%, 63.9%, and 8.9% at the applied concentrations of 0.05%, 0.5%, and 5%) was diminished by the application of nutrient-fortified PPPs (germination indices were 66.0–83.4% even at the highest doses). In pot experiments, most PPP treatments (especially Raw-PPP and the mixture of N- and P-fortified PPPs) promoted the development of aboveground plan...

Effect of immobilization of cells and/or presence of cyclodextrin on biodegradation of hydrophobic compounds

Szegedi Tudományegyetem, Aug 8, 2019

Szénhidrogén-szennyezések ózonkezeléssel intenzifikált membránszűrésének toxikológiai vonatkozásai

Impact of sewage sludge disposal on bacterial activity, nutrient and heavy metal content of Chernozem soils, Southeastern Hungary

EGU General Assembly Conference Abstracts, Apr 1, 2019

Changes in soil nutrient content, biological activity and CO2 emission rate as a result of low-dose municipal sewage sludge compost application

Biorefinery of Wastes of Meat Processing for Agricultural Applications

World Congress on Civil, Structural, and Environmental Engineering, 2020

Tremendous amount of keratin and bone wastes are generated daily in the poultry and meat industri... more Tremendous amount of keratin and bone wastes are generated daily in the poultry and meat industries in the world, which might be recycled as biofertilizers in agriculture. Recycling the biogenic elements (N, P, S, Ca) present in bone, feather or hair wastes facilitates these elements to return into the biogeochemical cycle. Mineralization of bone and feather wastes might provide essential elements for the agricultural plants [1,2,3]. For several popular crops, the sulfur supplementation has also serious economical impact [4]. Two bacteria were used, Pseudomonas sp. F1 can mobilize the P from bone. The supernatant of this culture supplemented with keratin was augmented with Bacillus licheniformis KK1. After one day and a week of incubation, the protein, orto-phosphate, TOC/TN and sulfate contents of the supernatants were measured. The supernatant of Pseudomonas sp. F1 contained orto-phosphate (released from bone) more than enough for the growth of Bacillus licheniformis KK1. The liquid containing soluble form of nitrogen, phosphorous, calcium and sulfur is an "easy to use" bio-based fertilizer targeting various cultivated plants. Biorefinery of food wastes for production of bio-products such as biofertilizer is one of the most promising environmentally sound processes, which is not only advantegous as waste management, but also leads to reduced dependence on non-renewable sources such as phosphate rocks (in production of P fertilisers).

Indirect effects of COVID-19 on the environment: How plastic contamination from disposable surgical masks affect early development of plants

Journal of Hazardous Materials

Isolation of hydrocarbonoclastic bacteria from oily wastes and their pilot application for water and soil decontamination

Excessive consumption of petroleum products carries the risk that these toxic chemicals enter and... more Excessive consumption of petroleum products carries the risk that these toxic chemicals enter and accumulate in the environment via transportation, usage or improper storage, thus hazarding natural habitats or human health. Bioremediation is a cost-effective and environmentally friendly technique that involves the use of microorganisms or plants in order to neutralize environmental pollutants. Considering that bacteria occur not only in aqueous but even in oil phases, intermediates, by-products or wastes can pose hidden reservoirs of effective microbial degraders with potential application in oil bioremediation. Using mazut (a residual fuel oil from atmospheric distillation of crude oil) as an origin matrix, thirteen bacterial strains were isolated. The best performing strains, identified as Rhodococcus sp. PAE1 and Rhodococcus sp. PAE8, were able to degrade structurally variant hydrophobic compounds (including hexadecane, cooking oil, mazut or lubricant oil) in aqueous systems. Thus, they were used in further small-scale soil/groundwater experiments in order to model the bioremediation process of a local ares exposed to years lubricant oil pollution. Our study represents a targeted tool for the bioremediation of oil-polluted aquatic and terrestrial environments and revealed that oily wastes can be considered as valuable sources of new hydrocarbon-utilizing isolates.

Sewage Sludge Compost Disposal on a Chernozem Soil: Impacts on Bacterial Activity and Nutrient Contents

New Prospects in Environmental Geosciences and Hydrogeosciences, 2022

Microbial degradation of hydrophobic compounds under various environmental conditions

Human activities related to industry, agriculture and increasing human population have a great im... more Human activities related to industry, agriculture and increasing human population have a great impact on the environment and easily lead to pollution jeopardizing natural habitats and ecosystems. Oil and its derivates from inadequate disposal and accidental spills are among the most common pollutants. Microbial degradation of these hydrophobic, organic compounds is a topic currently generating a great number of studies in environmental protection. The aim of this study is the comparison of two Rhodococcus strains isolated from soil and aqueous phase regarding the biodegradation efficacy in various environmental niches: minimal media, salted water and potting soil. Being aware of the changes of enzymes activity affected by various environmental conditions, we will be able to apply the most adequate microbial strains in bioremediation processes.

IL-17E production is elevated in the lungs of Balb/c mice in the later stages of Chlamydia muridarum infection and re-infection

In vivo, 2013

BACKGROUND Pathogens can influence allergic respiratory diseases. We previously found that multip... more BACKGROUND Pathogens can influence allergic respiratory diseases. We previously found that multiple infections with Chlamydophila pneumoniae induce the production of interleukin-17A (IL-17A) and IL-17E, which have roles in the pathogenesis of asthma. The present work was designed to investigate our hypothesis that infections with another pathogen can induce the production of IL-17A and IL-17E. MATERIALS AND METHODS At an internal of 28 days, mice were infected twice with Chlamydia muridarum; the kinetics of IL-17A and IL-17E expression was subsequently determined at the mRNA and protein levels. The amounts of IL-17 cytokines produced by the stimulated spleen cells were determined by enzyme-linked immunosorbent assay (ELISA). The presence of IL-17E in the lungs was revealed by an indirect immunofluorescence test. RESULTS The infection with C. muridarum induced the production of IL-17A at the early stages of infection. The quantity of IL-17E was highest on days 28 and 56 after the fir...

Method for increased biogas production in anaerobic thermophilic fermenters

Uso de una bacteria productora de hidrogeno, termofillica, anaerobia, acetogenica, para aumentar ... more Uso de una bacteria productora de hidrogeno, termofillica, anaerobia, acetogenica, para aumentar la produccion de metano en un sistema productor de biogas, en donde la biomasa se fermenta en condiciones anaerobias y termofilicas por un consorcio que comprende los microorganismos degradantes de polimeros, microorganismos acetogenicos y microorganismos metanogenicos.

Effects of Formulation Excipients on Skin Barrier Function in Creams Used in Pediatric Care

Pharmaceutics

Semisolid dosage forms are recommended for the dermal care of babies and children. If we look at ... more Semisolid dosage forms are recommended for the dermal care of babies and children. If we look at the ingredients of these preparations, there are still many cases in which there are substances (occlusive agents, preservatives) that no longer meet certain requirements of the modern age, so it is timely to replace them with other substances. The aim of this work was to formulate a science-based formulation with new components that keep or improve its moisturizing properties, rheological parameters, and microbiological stability. Occlusive oils, like white petrolatum and liquid paraffin and the preservative parabens are traditional ingredients in oil in water creams, were replaced with white beeswax, sunflower oil, and phenoxyethanol, respectively. Cocoa butter, urea, and glycerol were added to improve long-lasting hydration and support the barrier function of the reformulated creams. The rheological properties of the formulations were determined. The effects of the preparations on ski...

Impact of Low-Dose Municipal Sewage Sludge Compost Treatments on the Nutrient and the Heavy Metal Contents in a Chernozem Topsoil Near Újkígyós, Hungary: A 5-Year Comparison

Agriculture is one of the major fields, where sewage sludge can be used. Its high nutrient conten... more Agriculture is one of the major fields, where sewage sludge can be used. Its high nutrient content can contribute to the improvement of important soil properties, such as nutrient content, water balance and soil structure. However, sewage sludge may contain hazardous components, such as pathogens and pollutants. Therefore, it is important to monitor the effects of its field application. In this paper, we assessed the impacts of two low-dose (2.5 m3/ha) municipal sewage sludge compost applications (in 2013 and in 2017) in a 5.6 ha arable land in southeast Hungary (near Újkígyós), located in the Hungarian Great Plain. The nutrient and the heavy metal contents in the upper soil layer (0-30 cm) of the studied Chernozem soils were compared between two sampling campaigns in 2013 (before the compost applications) and in 2018 (after the compost applications). Basic soil properties (pH, salinity, humus content, carbonate content, Arany yarn number) complemented with nutrient content (K2O, P2...

Evaluation of Extracellular Organic Matter from Micrococcus luteus Effects on Hydrocarbon-Degrading Bacterial Communities

Effect of adaptation on hexane biodegradation by a rhodococcus strain capable of hydrocarbon utilization

Although organic solvents such as hexane have harmful effects on human health and natural environ... more Although organic solvents such as hexane have harmful effects on human health and natural environments, they are commonly used chemicals in several industrial fields. Bioremediation is an environmentally friendly and cost effective waste management technique for rehabilitation of polluted environments. A hydrocarbon-utilizing bacterial strain identified as a Rhodococcus sp. PAE1 was previously isolated from mazut. This new isolate was adapted to hexane in order to assess the effects of adaptation. The adapted strain exhibited a wide range of hexane tolerance and faster hexane biodegradation rate compared to the non-adapted strains. Adaptation to hexane combined with changes in cell membrane fatty acids resulted in increased cell surface hydrophobicity and elongation of cells that can promote the bioavailability of a water insoluble substrate.

Comparative metagenomic analyses of sheep and cow rumen contents and their effect on methane production of anaerobic batch fermentation

New Biotechnology

Assessment of potentially functional hydrocarbon-degrader bacterial communities in response to Micrococcus luteus EOM using culture-dependent and culture-independent methods

New Biotechnology

Novel Approaches to Exploit Microbial Hydrogen Metabolism

Publisher Summary The key enzyme in biological hydrogen (H2) metabolism is hydrogenase, which cat... more Publisher Summary The key enzyme in biological hydrogen (H2) metabolism is hydrogenase, which catalyzes the formation and decomposition of H2. Hydrogenases are metalloenzymes harboring Ni and Fe, or only Fe atoms, arranged in an exceptional structure. This chapter focuses on the hydrogenases with NiFe active centers. The best sources of hydrogenases, both for basic research and for forthcoming large-scale utilization, are micro-organisms that are cheap to cultivate and use sunlight to get energy for their growth. Thiocapsa roseopersicina (T. roseopersicin), which is a phototrophic bacterium, is one of the best candidates for studies of NiFe hydrogenase structure-function relationships and assembly because it contains four distinct NiFe hydrogenase molecular species. Methane-oxidizing bacteria (methanotrophs) have attracted considerable interest over the past twenty years because of their potential in producing bulk chemicals (e.g., propylene oxide) and single-cell protein and for use in biotransformation. Methanotrophs oxidize methane using the enzyme methane monooxygenase (MMO). Methanotrophic bacteria utilize H2 to supply reductant for their MMO enzyme systems. H2 driven enzyme activity plays a determining role in methane oxidation. Decomposition of wastes anaerobically to form biogas is one of the earliest applications of biotechnology, and H2 has an important role in anaerobic fermentation. This chapter discusses the results of a few experiments that were conducted to test whether H2 is a rate limiting substrate for methanogens.

Extracellular Organic Matter from Micrococcus luteus Enhances the Bioconversion of Used Lubricants in Polluted Soil

Extended Abstract Lubricant oils (LOs) are petroleum products manufactured for reducing friction ... more Extended Abstract Lubricant oils (LOs) are petroleum products manufactured for reducing friction between mechanical moving parts of machines. Combustion products, heavy metals, polychlorinated and polyaromatic hydrocarbons (PCBs and PAHs) accumulate in LOs under normal operation, hence used lubricant oils (ULOs) can pose a serious risk to human health or natural environments [1]. With the utilization of microorganisms or plants, bioremediation offers environmentally sound and cost-effective techniques for the decontamination of polluted sites [2]. However, application of living organisms in the field can be difficult due to the transition of inoculated bacteria into viable but nonculturable (VBNC) state when facing environmental stresses. Extracellular organic matter (EOM) from Micrococcus luteus can reverse this transition or enhance the biodegradation performance both of native and augmented strains [3-4]. In this study, bench-scale ex situ biodegradation experiments were performe...

Phytotoxicity evaluation of nutrient-fortified pomegranate peel powders prepared from food waste and their feasibility as biofertilizers

Environment, Development and Sustainability

Pomegranate peel powder (PPP) is increasingly used as a bioadsorbent to decontaminate wastewaters... more Pomegranate peel powder (PPP) is increasingly used as a bioadsorbent to decontaminate wastewaters due to its adsorptive characteristics. The application of nutrient-fortified bioadsorbents as alternatives to chemical fertilizers can provide an innovative and eco-friendly approach for sustainable waste management. Nevertheless, there is extremely limited information regarding their effects on the growth of agricultural crops. We investigated the effects of raw and nutrient-fortified PPPs on oilseed rape (Brassica napus). Our results showed that the concentration-dependent in vitro phytotoxicity of high PPP doses (germination indices were 109.6%, 63.9%, and 8.9% at the applied concentrations of 0.05%, 0.5%, and 5%) was diminished by the application of nutrient-fortified PPPs (germination indices were 66.0–83.4% even at the highest doses). In pot experiments, most PPP treatments (especially Raw-PPP and the mixture of N- and P-fortified PPPs) promoted the development of aboveground plan...

Effect of immobilization of cells and/or presence of cyclodextrin on biodegradation of hydrophobic compounds

Szegedi Tudományegyetem, Aug 8, 2019

Szénhidrogén-szennyezések ózonkezeléssel intenzifikált membránszűrésének toxikológiai vonatkozásai

Impact of sewage sludge disposal on bacterial activity, nutrient and heavy metal content of Chernozem soils, Southeastern Hungary

EGU General Assembly Conference Abstracts, Apr 1, 2019

Changes in soil nutrient content, biological activity and CO2 emission rate as a result of low-dose municipal sewage sludge compost application

Biorefinery of Wastes of Meat Processing for Agricultural Applications

World Congress on Civil, Structural, and Environmental Engineering, 2020

Tremendous amount of keratin and bone wastes are generated daily in the poultry and meat industri... more Tremendous amount of keratin and bone wastes are generated daily in the poultry and meat industries in the world, which might be recycled as biofertilizers in agriculture. Recycling the biogenic elements (N, P, S, Ca) present in bone, feather or hair wastes facilitates these elements to return into the biogeochemical cycle. Mineralization of bone and feather wastes might provide essential elements for the agricultural plants [1,2,3]. For several popular crops, the sulfur supplementation has also serious economical impact [4]. Two bacteria were used, Pseudomonas sp. F1 can mobilize the P from bone. The supernatant of this culture supplemented with keratin was augmented with Bacillus licheniformis KK1. After one day and a week of incubation, the protein, orto-phosphate, TOC/TN and sulfate contents of the supernatants were measured. The supernatant of Pseudomonas sp. F1 contained orto-phosphate (released from bone) more than enough for the growth of Bacillus licheniformis KK1. The liquid containing soluble form of nitrogen, phosphorous, calcium and sulfur is an "easy to use" bio-based fertilizer targeting various cultivated plants. Biorefinery of food wastes for production of bio-products such as biofertilizer is one of the most promising environmentally sound processes, which is not only advantegous as waste management, but also leads to reduced dependence on non-renewable sources such as phosphate rocks (in production of P fertilisers).

Indirect effects of COVID-19 on the environment: How plastic contamination from disposable surgical masks affect early development of plants

Journal of Hazardous Materials

Isolation of hydrocarbonoclastic bacteria from oily wastes and their pilot application for water and soil decontamination

Excessive consumption of petroleum products carries the risk that these toxic chemicals enter and... more Excessive consumption of petroleum products carries the risk that these toxic chemicals enter and accumulate in the environment via transportation, usage or improper storage, thus hazarding natural habitats or human health. Bioremediation is a cost-effective and environmentally friendly technique that involves the use of microorganisms or plants in order to neutralize environmental pollutants. Considering that bacteria occur not only in aqueous but even in oil phases, intermediates, by-products or wastes can pose hidden reservoirs of effective microbial degraders with potential application in oil bioremediation. Using mazut (a residual fuel oil from atmospheric distillation of crude oil) as an origin matrix, thirteen bacterial strains were isolated. The best performing strains, identified as Rhodococcus sp. PAE1 and Rhodococcus sp. PAE8, were able to degrade structurally variant hydrophobic compounds (including hexadecane, cooking oil, mazut or lubricant oil) in aqueous systems. Thus, they were used in further small-scale soil/groundwater experiments in order to model the bioremediation process of a local ares exposed to years lubricant oil pollution. Our study represents a targeted tool for the bioremediation of oil-polluted aquatic and terrestrial environments and revealed that oily wastes can be considered as valuable sources of new hydrocarbon-utilizing isolates.

Sewage Sludge Compost Disposal on a Chernozem Soil: Impacts on Bacterial Activity and Nutrient Contents

New Prospects in Environmental Geosciences and Hydrogeosciences, 2022

Microbial degradation of hydrophobic compounds under various environmental conditions

Human activities related to industry, agriculture and increasing human population have a great im... more Human activities related to industry, agriculture and increasing human population have a great impact on the environment and easily lead to pollution jeopardizing natural habitats and ecosystems. Oil and its derivates from inadequate disposal and accidental spills are among the most common pollutants. Microbial degradation of these hydrophobic, organic compounds is a topic currently generating a great number of studies in environmental protection. The aim of this study is the comparison of two Rhodococcus strains isolated from soil and aqueous phase regarding the biodegradation efficacy in various environmental niches: minimal media, salted water and potting soil. Being aware of the changes of enzymes activity affected by various environmental conditions, we will be able to apply the most adequate microbial strains in bioremediation processes.

IL-17E production is elevated in the lungs of Balb/c mice in the later stages of Chlamydia muridarum infection and re-infection

In vivo, 2013

BACKGROUND Pathogens can influence allergic respiratory diseases. We previously found that multip... more BACKGROUND Pathogens can influence allergic respiratory diseases. We previously found that multiple infections with Chlamydophila pneumoniae induce the production of interleukin-17A (IL-17A) and IL-17E, which have roles in the pathogenesis of asthma. The present work was designed to investigate our hypothesis that infections with another pathogen can induce the production of IL-17A and IL-17E. MATERIALS AND METHODS At an internal of 28 days, mice were infected twice with Chlamydia muridarum; the kinetics of IL-17A and IL-17E expression was subsequently determined at the mRNA and protein levels. The amounts of IL-17 cytokines produced by the stimulated spleen cells were determined by enzyme-linked immunosorbent assay (ELISA). The presence of IL-17E in the lungs was revealed by an indirect immunofluorescence test. RESULTS The infection with C. muridarum induced the production of IL-17A at the early stages of infection. The quantity of IL-17E was highest on days 28 and 56 after the fir...

Method for increased biogas production in anaerobic thermophilic fermenters

Uso de una bacteria productora de hidrogeno, termofillica, anaerobia, acetogenica, para aumentar ... more Uso de una bacteria productora de hidrogeno, termofillica, anaerobia, acetogenica, para aumentar la produccion de metano en un sistema productor de biogas, en donde la biomasa se fermenta en condiciones anaerobias y termofilicas por un consorcio que comprende los microorganismos degradantes de polimeros, microorganismos acetogenicos y microorganismos metanogenicos.

Effects of Formulation Excipients on Skin Barrier Function in Creams Used in Pediatric Care

Pharmaceutics

Semisolid dosage forms are recommended for the dermal care of babies and children. If we look at ... more Semisolid dosage forms are recommended for the dermal care of babies and children. If we look at the ingredients of these preparations, there are still many cases in which there are substances (occlusive agents, preservatives) that no longer meet certain requirements of the modern age, so it is timely to replace them with other substances. The aim of this work was to formulate a science-based formulation with new components that keep or improve its moisturizing properties, rheological parameters, and microbiological stability. Occlusive oils, like white petrolatum and liquid paraffin and the preservative parabens are traditional ingredients in oil in water creams, were replaced with white beeswax, sunflower oil, and phenoxyethanol, respectively. Cocoa butter, urea, and glycerol were added to improve long-lasting hydration and support the barrier function of the reformulated creams. The rheological properties of the formulations were determined. The effects of the preparations on ski...

Impact of Low-Dose Municipal Sewage Sludge Compost Treatments on the Nutrient and the Heavy Metal Contents in a Chernozem Topsoil Near Újkígyós, Hungary: A 5-Year Comparison

Agriculture is one of the major fields, where sewage sludge can be used. Its high nutrient conten... more Agriculture is one of the major fields, where sewage sludge can be used. Its high nutrient content can contribute to the improvement of important soil properties, such as nutrient content, water balance and soil structure. However, sewage sludge may contain hazardous components, such as pathogens and pollutants. Therefore, it is important to monitor the effects of its field application. In this paper, we assessed the impacts of two low-dose (2.5 m3/ha) municipal sewage sludge compost applications (in 2013 and in 2017) in a 5.6 ha arable land in southeast Hungary (near Újkígyós), located in the Hungarian Great Plain. The nutrient and the heavy metal contents in the upper soil layer (0-30 cm) of the studied Chernozem soils were compared between two sampling campaigns in 2013 (before the compost applications) and in 2018 (after the compost applications). Basic soil properties (pH, salinity, humus content, carbonate content, Arany yarn number) complemented with nutrient content (K2O, P2...

Evaluation of Extracellular Organic Matter from Micrococcus luteus Effects on Hydrocarbon-Degrading Bacterial Communities

Effect of adaptation on hexane biodegradation by a rhodococcus strain capable of hydrocarbon utilization

Although organic solvents such as hexane have harmful effects on human health and natural environ... more Although organic solvents such as hexane have harmful effects on human health and natural environments, they are commonly used chemicals in several industrial fields. Bioremediation is an environmentally friendly and cost effective waste management technique for rehabilitation of polluted environments. A hydrocarbon-utilizing bacterial strain identified as a Rhodococcus sp. PAE1 was previously isolated from mazut. This new isolate was adapted to hexane in order to assess the effects of adaptation. The adapted strain exhibited a wide range of hexane tolerance and faster hexane biodegradation rate compared to the non-adapted strains. Adaptation to hexane combined with changes in cell membrane fatty acids resulted in increased cell surface hydrophobicity and elongation of cells that can promote the bioavailability of a water insoluble substrate.

Comparative metagenomic analyses of sheep and cow rumen contents and their effect on methane production of anaerobic batch fermentation

New Biotechnology

Assessment of potentially functional hydrocarbon-degrader bacterial communities in response to Micrococcus luteus EOM using culture-dependent and culture-independent methods

New Biotechnology

Novel Approaches to Exploit Microbial Hydrogen Metabolism

Publisher Summary The key enzyme in biological hydrogen (H2) metabolism is hydrogenase, which cat... more Publisher Summary The key enzyme in biological hydrogen (H2) metabolism is hydrogenase, which catalyzes the formation and decomposition of H2. Hydrogenases are metalloenzymes harboring Ni and Fe, or only Fe atoms, arranged in an exceptional structure. This chapter focuses on the hydrogenases with NiFe active centers. The best sources of hydrogenases, both for basic research and for forthcoming large-scale utilization, are micro-organisms that are cheap to cultivate and use sunlight to get energy for their growth. Thiocapsa roseopersicina (T. roseopersicin), which is a phototrophic bacterium, is one of the best candidates for studies of NiFe hydrogenase structure-function relationships and assembly because it contains four distinct NiFe hydrogenase molecular species. Methane-oxidizing bacteria (methanotrophs) have attracted considerable interest over the past twenty years because of their potential in producing bulk chemicals (e.g., propylene oxide) and single-cell protein and for use in biotransformation. Methanotrophs oxidize methane using the enzyme methane monooxygenase (MMO). Methanotrophic bacteria utilize H2 to supply reductant for their MMO enzyme systems. H2 driven enzyme activity plays a determining role in methane oxidation. Decomposition of wastes anaerobically to form biogas is one of the earliest applications of biotechnology, and H2 has an important role in anaerobic fermentation. This chapter discusses the results of a few experiments that were conducted to test whether H2 is a rate limiting substrate for methanogens.

Extracellular Organic Matter from Micrococcus luteus Enhances the Bioconversion of Used Lubricants in Polluted Soil

Extended Abstract Lubricant oils (LOs) are petroleum products manufactured for reducing friction ... more Extended Abstract Lubricant oils (LOs) are petroleum products manufactured for reducing friction between mechanical moving parts of machines. Combustion products, heavy metals, polychlorinated and polyaromatic hydrocarbons (PCBs and PAHs) accumulate in LOs under normal operation, hence used lubricant oils (ULOs) can pose a serious risk to human health or natural environments [1]. With the utilization of microorganisms or plants, bioremediation offers environmentally sound and cost-effective techniques for the decontamination of polluted sites [2]. However, application of living organisms in the field can be difficult due to the transition of inoculated bacteria into viable but nonculturable (VBNC) state when facing environmental stresses. Extracellular organic matter (EOM) from Micrococcus luteus can reverse this transition or enhance the biodegradation performance both of native and augmented strains [3-4]. In this study, bench-scale ex situ biodegradation experiments were performe...