Assessment of intra-species diversity among strains of Acinetobacter baumannii isolated from sites contaminated with petroleum hydrocarbons

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. bauniannii.