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A total of 96 crude oil-degrading bacterial strains were isolated from 5 geographically diverse sites in India that were contaminated with different types of petroleum hydrocarbons. The strains were identified by sequencing the genes that encode for 16S rRNA. Out of the 96 isolates, 25 strains were identified as Acinetobacter baumannii and selected for the study. All of the selected strains could degrade the total petroleum hydrocarbon fractions of crude oil. These 25 strains were biochemically profiled and grouped into 8 phenovars on the basis of multivariate analysis of their substrate utilization profiles. PCR-based DNA fingerprinting was performed using intergenic repetitive DNA sequences, which divided the selected 25 strains into 7 specific genomic clusters. tRNA intergenic spacer length polymorphism was performed to determine the intra-species relatedness among these 25 strains. It delineated the strains into 8 genomic groups. The present study detected specific variants among the A. baumannii strains with differential degradation capacities for different fractions of crude oil. This could play a significant role in in situ bioremediation. The study also revealed the impact of environmental factors that cause intra-species diversity within the selected strains of A. baumannii.

The diversity among a set of bacterial strains that have the capacity to degrade total petroleum hydrocarbons (TPH) in soil contaminated with oily sludge (hazardous hydrocarbon waste from oil refineries) was determined. TPH is composed of alkane, aromatics, nitrogen-, sulfur-, and oxygen-containing compound, and asphaltene fractions of crude oil. The 150 bacterial isolates which could degrade TPH were isolated from soil samples obtained from diverse geoclimatic regions of India. All the isolates were biochemically characterized and identified with a Biolog microbial identification system and by 16S rDNA sequencing. Pseudomonas citronellolis predominated among the 150 isolates obtained from six different geographically diverse samplings. Of the isolates, 29 strains of P. citronellolis were selected for evaluating their genetic diversity. This was performed by molecular typing with repetitive sequence (Rep)-based PCR with primer sets ERIC (enterobacterial repetitive intergenic consensus), REP (repetitive extragenic palindromes), and BOXAIR and PCR-based ribotyping. Strain-specific and unique genotypic fingerprints were distinguished by these molecular typing strategies. The 29 strains of P. citronellolis were separated into 12 distinguishable genotypic groups by Rep-PCR and into seven genomic patterns by PCR-based ribotyping. The genetic diversity of the strains was related to the different geoclimatic isolation sites, type of oily sludge, and age of contamination of the sites. These results indicate that a combination of Rep-PCR fingerprinting and PCR-based ribotyping can be used as a high-resolution genomic fingerprinting method for elucidating intraspecies diversity among strains of P. citronellolis.

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