Mixed bacterial consortium can hamper the efficient degradation of crude oil hydrocarbons.

Crude oil degradation efficiency can be improved because of co-metabolism that exists when bacterial consortium is applied. However, because of possible vulnerability to environmental conditions and/or antagonistic interactions among members of the consortium, the degradation efficiency can be hampered. In this laboratory-based study, the biodegradation potentials of pure bacterial isolates namely Pseudomonas aeruginosa strain W15 (MW320658), Providencia vermicola strain W8 (MW320661) and Serratia marcescens strain W13 (MW320662) earlier isolated from crude oil-contaminated site and their consortium were evaluated using 3% crude oil-supplemented Bushnell Haas media. The efficiency was evaluated based on the viable cell count, biosurfactant analyses, percentage hydrocarbon degradation using gravimetric analysis and gas chromatography-mass spectrophotometry (GC-MS) analysis. There was decline in the population of W13 and predominance of W15 in the consortium as the incubation period progressed. Accelerated biodegradation of the crude oil hydrocarbons through co-metabolism was not achieved with the consortium; neither was there any improved resilience nor resistance to environmental changes of strain W13. The GC-MS analyses showed that the highest degradation was produced by W15 (48.23%) compared to W8 (46.04%), W13 (45.24%) and the Consortium (28.51%). The biodegradation of the crude oil hydrocarbons by W15, W8, W13 axenic cultures and their consortium treatments demonstrated that the bacterial constituent in a consortium can influence the synergistic effect that improves bioremediation. Future research that focuses on evaluating possible improvement in bioremediation through maintenance of diversity by continuous bioaugmentation using vulnerable but efficient degraders in a consortium is necessary to further understand the application of consortia for bioremediation improvement.

Population dynamics and crude oil degrading ability of bacterial consortia of isolates from oil-contaminated sites in Nigeria / Dinámica de la población y capacidad de degradación del petróleo crudo de consorcios bacterianos de aislamientos de sitios contaminados con petróleo en Nigeria

Application of bacterial consortium of hydrocarbon degraders to crude oil–contaminated site can enhance bioremediation. This study evaluated the population dynamics and crude oil degradation abilities of various consortia developed from bacterial strains isolated from crude oil–contaminated sites using crude oil–supplemented Bushnell Haas media. Each consortium consisted of three bacterial strains and was designated as Consortium A (Serratia marcescens strain N4, Pseudomonas aeruginosa strain N3R, Pseudomonas aeruginosa strain W11), B (Pseudomonas aeruginosa strain N3R, Pseudomonas aeruginosa strain W11, Pseudomonas protegens strain P7), C (Serratia marcescens strain N4, Pseudomonas aeruginosa strain W11, Pseudomonas protegens strain P7), and D (Pseudomonas aeruginosa strain W15, Providencia vermicola strain W8, Serratia marcescens strain W13). There was progressive decline in the populations of Serratia marcescens strains in the consortia as the incubation period progressed. This may have led to reduction in their synergistic contribution and, subsequently, total degradation ability of crude oil by the consortia. The gravimetric analyses showed that Consortium D produced the highest % crude oil degradation of 29.66% compared to Consortia A, B, and C with 23.73%, 11.86%, and 19.49% respectively. Based on gas chromatography–mass spectrometry analyses, Consortium D produced the highest percentage total petroleum hydrocarbon degradation of 73.65% compared to 68.24%, 68.94%, and 69.19% produced by Consortia A, B, and C respectively. The biodegradation potential of Consortium D also demonstrates the significance of using isolates from the same isolation site in development of consortium for bioremediation.(AU)

Population dynamics and crude oil degrading ability of bacterial consortia of isolates from oil-contaminated sites in Nigeria.

Application of bacterial consortium of hydrocarbon degraders to crude oil-contaminated site can enhance bioremediation. This study evaluated the population dynamics and crude oil degradation abilities of various consortia developed from bacterial strains isolated from crude oil-contaminated sites using crude oil-supplemented Bushnell Haas media. Each consortium consisted of three bacterial strains and was designated as Consortium A (Serratia marcescens strain N4, Pseudomonas aeruginosa strain N3R, Pseudomonas aeruginosa strain W11), B (Pseudomonas aeruginosa strain N3R, Pseudomonas aeruginosa strain W11, Pseudomonas protegens strain P7), C (Serratia marcescens strain N4, Pseudomonas aeruginosa strain W11, Pseudomonas protegens strain P7), and D (Pseudomonas aeruginosa strain W15, Providencia vermicola strain W8, Serratia marcescens strain W13). There was progressive decline in the populations of Serratia marcescens strains in the consortia as the incubation period progressed. This may have led to reduction in their synergistic contribution and, subsequently, total degradation ability of crude oil by the consortia. The gravimetric analyses showed that Consortium D produced the highest % crude oil degradation of 29.66% compared to Consortia A, B, and C with 23.73%, 11.86%, and 19.49% respectively. Based on gas chromatography-mass spectrometry analyses, Consortium D produced the highest percentage total petroleum hydrocarbon degradation of 73.65% compared to 68.24%, 68.94%, and 69.19% produced by Consortia A, B, and C respectively. The biodegradation potential of Consortium D also demonstrates the significance of using isolates from the same isolation site in development of consortium for bioremediation.

Oxidation of glucose by syntrophic association between Geobacter and hydrogenotrophic methanogens in microbial fuel cell.

OBJECTIVE: To investigate a syntrophic interaction between Geobacter sulfurreducens and hydrogenotrophic methanogens in sludge-inoculated microbial fuel cell (MFC) systems running on glucose with an improved electron recovery at the anode. RESULTS: The presence of archaea in MFC reduces Coulombic efficiency (CE) due to their electron scavenging capability but, here, we demonstrate that a syntrophic interaction can occur between G. sulfurreducens and hydrogenotrophic methanogens via interspecies H2 transfer with improvement in CE and power density. The addition of the methanogenesis inhibitor, 2-bromoethanesulfonate (BES), resulted in the reduction in power density from 5.29 to 2 W/m3, and then gradually increased to the peak value of 5.5 W/m3 when BES addition was stopped. CONCLUSION: Reduction of H2 partial pressure by archaea is an efficient approach in improving power output in a glucose-fed MFC system using Geobacter sp. as an inoculum.

Secondary metabolites from a strain of Alternaria tenuissima Isolated from Northern Manitoba soil.

Deoxyphomalone (1), dimethyl 4-methyl-2,6-pyridinedicarboxylate (2), stemphyperylenol (3), and N-methyl-2-pyrrolidone (4) were isolated from the fermentation broth of a strain of the fungus, Alternaria tenuissima. This fungus was isolated from the soil underlying the lichen, Peltigera didactyla, which had been collected from Wapusk National Park in Northern Manitoba. The structures of the compounds were determined by comprehensive analysis of their spectroscopic data including FT-IR, 1D and 2D NMR spectroscopy and mass spectrometry; and their bioactivities were tested against E.coli cells. The taxonomic identity of the fungus was confirmed by ITS sequencing of its ribosomal DNA.