title: Biostimulation of Indigenous Microbial Community for Bioremediation of Petroleum Refinery Sludge.
abstract: Nutrient deficiency severely impairs the catabolic activity of indigenous microorganisms in hydrocarbon rich environments (HREs) and limits the rate of intrinsic bioremediation. The present study aimed to characterize the microbial community in refinery waste and evaluate the scope for biostimulation basedin situbioremediation. Samples recovered from the wastewater lagoon of Guwahati refinery revealed a hydrocarbon enriched [high total petroleum hydrocarbon (TPH)], oxygen-, moisture-limited, reducing environment. Intrinsic biodegradation ability of the indigenous microorganisms was enhanced significantly (>80% reduction in TPH by 90 days) with nitrate amendment. Preferred utilization of both higher- (>C30) and middle- chain (C20-30) length hydrocarbons were evident from GC-MS analysis. Denaturing gradient gel electrophoresis and community level physiological profiling analyses indicated distinct shift in community's composition and metabolic abilities following nitrogen (N) amendment. High throughput deep sequencing of 16S rRNA gene showed that the native community was mainly composed of hydrocarbon degrading, syntrophic, methanogenic, nitrate/iron/sulfur reducing facultative anaerobic bacteria and archaebacteria, affiliated to γ- and δ-ProteobacteriaandEuryarchaeotarespectively. Genes for aerobic and anaerobic alkane metabolism (alkB andbssA), methanogenesis (mcrA), denitrification (nirS andnarG) and N2fixation (nifH) were detected. Concomitant to hydrocarbon degradation, lowering of dissolve O2and increase in oxidation-reduction potential (ORP) marked with an enrichment of N2fixing, nitrate reducing aerobic/facultative anaerobic members [e.g., Azovibrio,PseudoxanthomonasandComamonadaceaemembers] was evident in N amended microcosm. This study highlighted that indigenous community of refinery sludge was intrinsically diverse, yet appreciable rate ofin situbioremediation could be achieved by supplying adequate N sources.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Kharagpur, India.
authors.forename: Jayeeta
authors.initials: J
authors.lastname: Sarkar
authors.affiliation: Department of Biotechnology, National Institute of Technology Durgapur, India.
authors.forename: Sufia K
authors.initials: SK
authors.lastname: Kazy
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Kharagpur, India.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Gupta
authors.affiliation: School of Bioscience, Indian Institute of Technology Kharagpur, India.
authors.forename: Avishek
authors.initials: A
authors.lastname: Dutta
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Kharagpur, India.
authors.forename: Balaram
authors.initials: B
authors.lastname: Mohapatra
authors.affiliation: Department of Biotechnology, National Institute of Technology Durgapur, India.
authors.forename: Ajoy
authors.initials: A
authors.lastname: Roy
authors.affiliation: Department of Agricultural and Food Engineering, Indian Institute of Technology Kharagpur, India.
authors.forename: Paramita
authors.initials: P
authors.lastname: Bera
authors.affiliation: Department of Agricultural and Food Engineering, Indian Institute of Technology Kharagpur, India.
authors.forename: Adinpunya
authors.initials: A
authors.lastname: Mitra
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Kharagpur, India.
authors.forename: Pinaki
authors.initials: P
authors.lastname: Sar
keywords: bioremediation; biostimulation; microbial community; next generation sequencing; petroleum refinery sludge