Enhanced Biodegradation and Detoxification of Diesel in Soil and Water Using a Novel Mixed Bacterial Culture

This study evaluates a novel mixed bacterial culture, comprising Acinetobacter baumannii IITG19, Klebsiella michiganensis RK, Providencia vermicola IITG20, and Pseudomonas aeruginosa IITG21, for its effectiveness in remediating diesel-contaminated soil and water. Through in-Lab degradation efficiency tests, simulated field studies, phytotoxicity tests, and degradation kinetics analysis, the potential of this culture was explored. During in-Lab study, the mixed culture showed 90% degradation of 4% v/v diesel over 15 days, at 35 °C temperature, pH 7, and 1% v/v inoculum concentration. Subsequent field studies showed diesel degradation of 96 and 99% in soil and water, respectively. The mixed culture showed 97% degradation of n-alkanes and branched alkanes and 96% degradation of naphthenes and aromatics in soil. In water, it showed over 99% degradation for all components. Phytotoxicity assessments with Brassica nigra seeds, ascertained successful growth in mixed culture-treated soil and water due to remediation. Degradation kinetics analysis confirmed first-order degradation, with a rate constant (k) of 0.144 day^-1 for in-Lab study. Field studies yielded values of 0.196 day^-1 for soil and 0.288 day^-1 for water. These findings showed that the mixed bacterial culture in this study was not only able to remove diesel contamination from soil and water but also restored soil health for plant growth. Its efficient performance under field-like conditions established its real potential for use in large-scale environmental clean-up efforts.