Investigation of microbial diversity and prediction of functional genes involved in aromatic hydrocarbon degradation in Nyband Gulf

Nayband Gulf is subjected to oil pollution due to the proximity to Assaluyeh industrial region. Prolonged exposure to contaminants affects the microbial population and shifts the population to the predominance of oil-degrading microbes. In this study, we  investigate the microbial diversity in Nayband Gulf waters and predict the genes involved in aromatic hydrocarbon degradation under aerobic and anaerobic conditions.

Phenol-chloroform method was performed for extracting DNA from the Nayband Gulf water sample. Extracted DNA sequencing was performed by new generation  sequencing technique. Then 16S rRNA gene-based amplicon sequencing was analyzed. Functional genes involved in the degradation of aromatic hydrocarbons under aerobic and anaerobic conditions were predicted from 16S rRNA gene sequences.

Our findings indicate that aromatic hydrocarbons contamination in Nayband Gulf water resulted in the enrichment of Oceanospirillales (24.67%), Cellvibrionales (28.95%), SAR11 clade (20.97%), Rhodobacterales (6.17%), Rhodospirillales (7.12%) and Flavobacteriales (5.50%).  Alphaproteobacteria (26.18%) and Gammaproteobacteria (42.23%) had the highest percentage. According to Phylogenetic Investigation of Communities by Reconstruction of Unobserved States, the genes involved in degradation of naphthalene under anaerobic conditions were most abundant in the sample.

The results of this study showed that long-term exposure to oil pollution and oil spills affects the microbial population. The microbial population of Nayband Gulf region, due to its proximity to the South Pars oil & gas region and the entry of oil pollutants into the water, has caused the domination of petroleum hydrocarbons degrading bacteria.