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Microbial remediation is an efficient method of removing paraffin wax from oil wells and pipelines and is found to be environment friendly and economical. In this study, a potential paraffin wax degrading bacterial strain was isolated from oil wells of Gujarat and was identified as Pseudomonas nitroreducens by 16S rRNA sequencing. Pseudomonas nitroreducens showed 100% utilization of heneicosane, 79.74% utilization of pentacosane and 72.50% utilization of triacontane, the major components of paraffin wax in 8 days at 37°C. Pseudomonas nitroreducens degraded 70% of paraffinic crude oil in 10 days at 37°C. The probable end products formed after degradation of eicosane and heneicosane by Pseudomonas nitroreducens were analysed by Mass Spectrum. The above results proving isolate as a potential candidate for degradation of paraffin wax in oil wells. [ABSTRACT FROM AUTHOR]

Petroleum refineries generate oily sludge that contains hazardous polycyclic aromatic hydrocarbons (PAH), and hence, its proper disposal is of foremost concern. Analysis of the physicochemical properties and functions of indigenous microbes of the contaminated sites are essential in deciding the strategy for bioremediation. This study analyses both parameters at two geographically distant sites, with different crude oil sources, and compares the metabolic capability of soil bacteria with reference to different contamination sources and the age of the contaminated site. The results indicate that organic carbon and total nitrogen derived from petroleum hydrocarbon negatively affect microbial diversity. Contamination levels vary widely on site, with levels of PAHs ranging from 5.04 to 1.66 × 103 μg kg−1 and 6.20 to 5.64 × 103 μg kg−1 in Assam and Gujarat sites respectively, covering a higher proportion of low molecular weight (LMW) PAHs (fluorene, phenanthrene, pyrene, and anthracene). Functional diversity values were observed to be positively correlated (p < 0.05) with acenaphthylene, fluorene, anthracene, and phenanthrene. Microbial diversity was the highest in fresh oily sludge which decreased upon storage, indicating that immediate bioremediation, soon after its generation, would be beneficial. Improvement in the bio-accessibility of hydrocarbon compounds by the treatment of biosurfactant produced by a (soil isolate/isolate) was demonstrated., with respect to substrate utilization. [Display omitted] • Aged oil contaminated soil alters the soil physiochemical and native microflora. • Bioavailability and sequestration reduce as molecular weight of hydrocarbon increases. • Longer and improper sludge storage negatively impact microbial community survival. • Functional microbial diversity was found high for fresh oily sludge. • Biosurfactant enhanced substrate utilization improving microbial potential for bioremediation. [ABSTRACT FROM AUTHOR]