Microbial Community Profiling of Active Oleophilic Bacteria involved in Bioreactor-based Crude-oil Polluted Sediment Treatment

摘要

Petroleum hydrocarbon pollution has been a major environmental challenge in the coastal areas, Niger-Delta, Nigeria. In this study, culture dependent and molecular techniques were used to monitor bioremediation over a-64 day period in seven microcosms setup in 2.5 L stirred tank bioreactors with each tank containing either Poultry droppings (BPOUT), NPK fertilizer (BNPK), Cow dung (BCD) or Urea fertilizer (BUREA). One bioreactor (BAUG) was bioaugmented while two others served as unamended (BUNa) and heat-killed (BHKD) controls. A decrease in petroleum hydrocarbon concentration and a concomitant increase in biomass was observed in all treatments at varying levels. BNPK (97.2%; 97.1%) showed highest reduction percentage while BHKD (82.34%, 81.3%) was the least for total petroleum hydrocarbon and polycyclic aromatic hydrocarbon amongst all treatment. Screening of isolates for aromatic hydrocarbon ring cleavage functional gene (catechol 2,3-dioxygenase) revealed that catechol 2,3-dioxygenase (C23D0) gene was detected in the following genera: Pseudomonas spp. (3), Rhodococcus sp. (2), Bacillus spp.(2)., Achromobacter sp., Serratia sp., Aeromonas sp., Micrococcus sp. and Acinetobacter sp. Sequences obtained from amplification of 16S rRNA gene gave a total number of 24 hydrocarbon utilizing bacterial species which showed 96-100% similarity with those deposited in GenBank and are identified as Brevundimonas naejangsanensis, Pseudomonas pseudoalcaligenes, Pseudomonas spp. (6), Aquitalea magnusonii, Achromobacter sp., Halomonas lutea, Pseudomonas aeruginosa (8), Shewanella sp, Achromobacter sp., Gordonia sp., Sphingobacterium sp. and Bacillus sp. Our result revealed that these extant indigenous bacterial population in the crude oil-polluted sediment habour the relevant aromatic hydrocarbon ring cleavage genes (catechol 2,3-dioxygenase) and may have a key role in bioremediation of crude oil-polluted sediment.