Elucidation of molecular diversity and functional characterization of phenanthrene degrading consortium NS-PAH-2015-PNP-5

Phenanthrene (PHE) is a hazardous low molecular weight PAH and widespread ecological contaminant. In the present study, the Illumina Miseq platform explored the bacterial diversity of the efficient PHE degrading consortium NS-PAH-2015-PNP-5, developed from the petrochemical contaminated soil near the Indian Oil Corporation Limited refinery, Panipat (India). Total 273 OTUs represented the species diversity identified in NS-PAH-2015-PNP-5. Nineteen major bacterial species covered approximately 99.22% of the total alpha-diversity of NS-PAH-2015-PNP-5. In NS-PAH-2015-PNP-5, the Shannon alpha diversity (H') and Pielou's Evenness Index (J') were calculated at 2.43 and 0.43, respectively. Moreover, an overwhelming population of phylum Proteobacteria (99.28%) and Pseudomonas spp. (32.25%) were observed in NS-PAH-2015-PNP-5. Two culturable isolates, PAH 51 and PAH 52, were isolated from the NS-PAH-2015-PNP-5, and the result of 16S rRNA analysis showed homology with Bacillus wiedmannii (96.7%) and Achromobacter pulmonis (99.24%), respectively. The results of the carbohydrate utilization test showed that NS-PAH-2015-PNP-5 was able to metabolize dextrose, L-arabinose, ONPG, esculin, citrate, and malonate. Detection of phthalic acid metabolite by the GCMS analysis inferred that NS-PAH-2015-PNP-5 bio-degraded the PHE through the protocatechuic acid pathway. During the seven-day biodegradation experiment at the optimized physicochemical conditions, NS-PAH-2015-PNP-5 degraded 62%, 70%, 90% PHE after the third, fifth, and seventh day, respectively.

Automated summary

In this study, the bacterial diversity of the efficient PHE degrading consortium NS-PAH-2015-PNP-5 was explored using the Illumina Miseq platform. The results revealed a diverse bacterial community in NS-PAH-2015-PNP-5, with Proteobacteria and Pseudomonas spp. being the major members. Two culturable isolates were identified, and it was found that NS-PAH-2015-PNP-5 metabolized PHE through the protocatechuic acid pathway.