33 research outputs found
Laboratory studies of rice bran as a carbon source to stimulate indigenous microorganisms in oil reservoirs
Microbial Community Analysis of a Coastal Salt Marsh Affected by the Deepwater Horizon Oil Spill
Conceived and designed the experiments: MJB RJM BM PAS. Performed the experiments: MJB RJM SR JP YMP LMT JDVN. Analyzed the data: MJB RJM YMP LMT GLA TCH JDVN JZ PAS. Contributed reagents/materials/analysis tools: GLA TCH JZ BM PAS. Wrote the paper: MJB RJM PAS.Coastal salt marshes are highly sensitive wetland ecosystems that can sustain long-term impacts from anthropogenic events such as oil spills. In this study, we examined the microbial communities of a Gulf of Mexico coastal salt marsh during and after the influx of petroleum hydrocarbons following the Deepwater Horizon oil spill. Total hydrocarbon concentrations in salt marsh sediments were highest in June and July 2010 and decreased in September 2010. Coupled PhyloChip and GeoChip microarray analyses demonstrated that the microbial community structure and function of the extant salt marsh hydrocarbon-degrading microbial populations changed significantly during the study. The relative richness and abundance of phyla containing previously described hydrocarbon-degrading bacteria (Proteobacteria, Bacteroidetes, and Actinobacteria) increased in hydrocarbon-contaminated sediments and then decreased once hydrocarbons were below detection. Firmicutes, however, continued to increase in relative richness and abundance after hydrocarbon concentrations were below detection. Functional genes involved in hydrocarbon degradation were enriched in hydrocarbon-contaminated sediments then declined significantly (p<0.05) once hydrocarbon concentrations decreased. A greater decrease in hydrocarbon concentrations among marsh grass sediments compared to inlet sediments (lacking marsh grass) suggests that the marsh rhizosphere microbial communities could also be contributing to hydrocarbon degradation. The results of this study provide a comprehensive view of microbial community structural and functional dynamics within perturbed salt marsh ecosystems.Yeshttp://www.plosone.org/static/editorial#pee
Biodegradation of polycyclic aromatic hydrocarbon by a halotolerant bacterial consortium isolated from marine environment
The biodegradability of polycyclic aromatic hydrocarbons such as
naphthalene, fluorene, anthracene and phenanthrene by a halotolerant
bacterial consortium isolated from marine environment was investigated.
The polycyclic aromatic hydrocarbons degrading bacterial consortium was
enriched from mixture saline water samples collected from Chennai (Port
of Chennai, salt pan), India. The consortium potently degraded
polycyclic aromatic hydrocarbons (> 95%) at 30g/L of sodium chloride
concentration in 4 days. The consortium was able to degrade 39 to 45%
of different polycyclic hydrocarbons at 60 g/L NaCl concentration. Due
to increase in salinity, the percent degradation decreased. To enhance
polycyclic aromatic hydrocarbons degradation, yeast extract was added
as an additional substrate at 60g/L NaCl concentration. After the
addition of yeast extract, the consortium degraded > 74 % of
polycyclic aromatic hydrocarbons at 60 g/L NaCl concentration in 4
days. The consortium was also able to degrade PAHs at different
concentrations (5, 10, 20, 50 and 100 ppm) with 30 g/L of NaCl
concentration. The polycyclic aromatic hydrocarbons degrading
halotolerant bacterial consortium consists of three bacterial strains,
namely Ochrobactrum sp., Enterobacter cloacae and Stenotrophomonas
maltophilia
Effects of sludge pretreatment on sludge reduction in a lab-scale anaerobic/anoxic/oxic system treating domestic wastewater
Excess sludge disposal is one of the serious challenges in biological
wastewater treatment. Reduction of sludge production would be an ideal
way to solve sludge-associated problems rather than the post-treatment
of the sludge produced. In this study, a new wastewater treatment
process combining anaerobic/anoxic/oxic system with thermochemical
sludge pretreatment was tested in a laboratory scale experiment. In
this study, the effects of the sludge pretreatment on the excess sludge
production in anaerobic/anoxic/oxic were investigated. The system was
operated in two Runs (1 and 2). In Run 1, the system was operated as a
reference and in Run 2, a part of the mixed liquid was pretreated
thermochemically and was returned to the bioreactor. The average
solubilization efficiency of pretreated sludge was found to be about 35
% during the study period of 220 days. Sludge production rate in Run 2
was less than that in Run 1 by about 52 %. Total phosphorous was
removed by enhanced biological phosphorous removal with the removal
efficiency of 83–87 % and 81–83 % for Run 1 and Run 2,
respectively. Total nitrogen removal in Run 2 (79–82 %) was
slightly higher than that in Run 1 (68–75 %). The mixed liquor
suspended solids/mixed liquor volatile suspended solids ratio was
identical after both runs in the range 78–83 %. The effluent
water qualities were not significantly affected when operated with
thermochemical pretreatment at pH 11 and 60 °C for 3 h during 7
months. From the present study it is concluded that thermochemical
sludge pretreatment of anaerobic/anoxic/oxic process plays an important
role in reduction of sludge production