Exploring bacterial communities through metagenomics during bioremediation of polycyclic aromatic hydrocarbons from contaminated sediments

The goal of this study was to evaluate the degradation effectiveness of PAHs degrading bacteria at the mesocosm level, including Stenotrophomonas maltophilia (SC), mixed culture (MC), and enriched native microflora (EC) at the mesocosm level. Maximum degradation was found in the mesocosm MC (26.67 %), followed by SC (25.08 %) and EC (18.25 %) after 60 days. Thus, mixed culture and Stenotrophomonas maltophilia could be a game changer in the PAHs bioremediation at the chronically contaminated sites. MiSeq sequencing has revealed dominancy of gamma-Proteobacteria, alpha-Proteobacteria, beta-Proteobacteria at class level and Sphingomonadales, oceanospirillales, Rhodothermales at Order level. Families Alcanivoracaceae, Alteromonadaceae, Nocardiaceae, Rhodospirillaceae and genus Stenotrophomonas, Alcanivorax, Methylophaga, Fluviicola and Rhodoplanes were considerably increased which play key role in the PAHs degradation. Dominant bacterial communities have revealed resilience community to enable potential PAHs degradation process in all the mesocosms. To the best our knowledge this is the first ever attempt in PAHs biodegradation study conducted at the mesocosm level mimicking natural environmental conditions. Consequently, this study could be a benchmark against which future progress studies for the policy makers and stakeholders to design appropriate bioremediation study for the historically PAHs polluted contaminate sites.

Automated summary

This study evaluated the effectiveness of PAHs degrading bacteria, including Stenotrophomonas maltophilia, mixed culture, and enriched native microflora at the mesocosm level. The results showed that the mixed culture had the highest degradation rate, followed by Stenotrophomonas maltophilia and enriched native microflora. MiSeq sequencing revealed the dominant bacterial communities and families and genera that play a key role in PAHs degradation. This study provides important insights for future bioremediation studies and policy-making.