Prospects of Stenotrophomonas pavanii DB1 in diesel utilization and reduction of its phytotoxicity on Vigna radiata

Abstract

Diesel, for its carcinogenic and teratogenic properties, is considered as an environmental hazard. The present study concentrates on diesel utilization by Stenotrophomonas pavanii DB1 under various physicochemical parameters and mass spectral analysis of the metabolites produced. Soil remediation potential of the culture for reducing diesel toxicity against Vigna radiata seed germination was also evaluated. Supplementation of the broth with ammonium sulfate, molasses and tween 80 enhanced diesel utilization (up to 66.3%). A steady decrease in diesel utilization (69.46–51.23%) was recorded with the increase in salinity from 1 to 5000 mM. Similarly, the utilization efficiency was low (up to 11.5%) when cadmium, lead and mercury salts were present but was not affected by zinc and copper salts. Liquid chromatography–mass spectrometry revealed extensive utilization (95–99%) of both the short- (C10–C20) and long-chain (C18–C30) n-alkanes. Significantly, the culture exhibited uniform utilization of various recalcitrant n-alkanes, to generate metabolites like aldehyde, ketone, fatty acids, carboxylic and dicarboxylic acids. Stenotrophomonas pavanii DB1 mediated 95% and 86% of diesel utilization in soil with and without nutrient amendment, respectively. Germination percentage of V. radiata seeds improved with the bacterial inoculation of the diesel-containing soil. Stenotrophomonas pavanii DB1 culture did not establish antagonistic effect over the resident soil bacteria. Based on the spectral analysis and soil remediation studies, it could be inferred that S. pavanii DB1 is a potential culture for bioremediation of sites polluted with diesel.