Biodegradation of diesel oil and n-alkanes (C18, C20, and C22) by a novel strain acinetobacter sp. K-6 in unsaturated soil

Abstract

A large residual fraction of aliphatic components of diesel prevails in soil, which has adverse effects on the environment. This study identified the most bio-recalcitrant aliphatic residual fraction of diesel through total petroleum-hydrocarbon fractional analysis. For this, the strain Acinetobacter sp. K-6 was isolated, identified, and characterized and investigated its ability to degrade diesel and n-alkanes (C18, C20, and C22). The removal efficiency was analysed after treatment with bacteria and nutrients in various soil microcosms. The fractional analysis of diesel degradation after treatment with the bacterial strains identified C18-C22 hydrocarbons as the most bio-recalcitrant aliphatic fraction of diesel oil. Acinetobacter sp. K-6 degraded 59.2% of diesel oil and 56.4% of C18-C22 hydrocarbons in the contaminated soil. The degradation efficiency was further improved using a combinatorial approach of biostimulation and bioaugmentation, which resulted in 76.7% and 73.7% higher degradation of diesel oil and C18-C22 hydrocarbons, respectively. The findings of this study suggest that the removal of mid-length, non-volatile hydrocarbons is affected by the population of bio-degraders and the nutrients used in the process of remediation. A combinatorial approach, including biostimulation and bioaugmentation, could be used to effectively remove large quantities of aliphatic hydrocarbons persisting for a longer period in the soil.