USE OF ILLUMINA 16S rRNA NEXT GENERATION SEQUENCING TO INVESTIGATE ANAEROBIC BACTERIAL COMMUNITY COMPOSITION IN ENVIRONMENTAL AND FUEL ASSOCIATED WATERS

摘要

Sulphate-reducing Bacteria (SRB) are anaerobic microorganisms that use sulphate as an electron acceptor, generating H2S as the product of respiration, leading to acidification and, ultimately, corrosion. The oil industry can be affected by unexpected generation of H2S by SRB in locations where fuel becomes contaminated with water, e.g. fuel storage tanks, fuel tanks of marine crafts, or legs of oilrigs. Therefore, the detection of SRB-contaminated fuel sources becomes critical, requiring analytical and quantitative assays to detect the microbial content. The aim of the present study was to describe the Illumina 16S rRNA Next Generation Sequencing (NGS) performed on seven samples that were chosen in two different combinations, focusing on two types of observations. The first objective was to investigate the differences in the bacterial community composition (BCC) of the three hypoxic samples derived from: estuarine mud (EST), the silt layer of a shallow pond (POND) and from an old diesel tank from a farm (PHIL4). The second part of the study was concerned with the fuel sample PHIL4, and investigated the effect on the BCC of two SRB-enhancing liquid media: Postgate's B (PGB) and Postgate's C (PGC) at two different incubation times (2 and 9 days). Samples PHIL4 and EST shared a similar BCC, and this differed from that of POND. Overall, POND was the least diverse of the three samples, and mostly consisted of Clostridia (74.5%). Clostridia and Gammaproteobacteria were the most variable taxa observed in PHIL4, EST, and POND. Similarly, Clostridia and Gammaproteobacteria showed large variability in PHIL4 with PGB and PGC. Longer incubation time (9 days vs 2 days) resulted in a decrease of Gammaproteobacteria and an increase of Clostridia. An increase in relative richness of Clostridia was due to the increased development of Blautia spp. This trend was seen in POND, and similarly in PHIL4 with PGB after 9 days of incubation.