Isolation and characterization of phenanthrene-degrading bacteria from urban soil

Phenanthrene (PHE) is one of the most abundant Polycyclic Aromatic Hydrocarbons (PAHs) found in urban soil. So far, majority of microbe-mediated degradation approaches have relied on microbes isolated from polluted or mined soils. These microbes, if introduced into non-native soil, may not able to establish themselves, or alter the native microbiome of soil, making their commercial use a challenge. Therefore, this study was conducted to screen and isolate bacteria, from urban soil that degrade PHE. Degradation of 50 mg/L PHE by day 4 was highest in Providencia rettgeri VMP5 (98.63%) followed by Bacillus tropicus VMP4 (89.9%), Bacillus sp. VMP2 (82.63%), P. stuartii VMP3 (39.72%) and least Dellaglioa algida VMP1 (3.32%). Besides, VMP5, showed the presence of several fatty acid ethyl esters that act as biosurfactants and anti-microbial agent, which may play a crucial role in increasing its adaptability and degradation potential. VMP4 and VMP2 were also found to produce more defense compounds which may be crucial for their adaptability to PAH rich environment. Thus, VMP5, VMP4 and VMP2 showed promising remediation potential that can be further explored to develop commercially viable consortia for PHE mitigation in urban soil.