Rhizobacterial community of Jatropha curcas associated with pyrene biodegradation by consortium of PAH-degrading bacteria

A bacterial consortium consisting five efficient polyaromatic hydrocarbon (PAH) degraders (Pseudomonas aeruginosa PDB1, Pseudomonas fragi DBC, Klebsiella pneumoniae AWD5, Alcaligenes faecalis BDB4 and Acinetobacter sp. PDB4) was bioaugmented in pyrene contaminated soil through Jatropha curcas rhizosphere, to understand its effect on changes in bacterial community structure during the process of rhizosphere mediated biodegradation of pyrene. This consortium was highly effective in rhizosphere mediated remediation, as 97.2% of pyrene was degraded within 60 days. The better degradation of pyrene in soil was correlated with the changes in bacterial community structure in rhizosphere of J. curcas, for different trials. The Proteobacteria remained the most abundant group among different treatments, but its abundance was 30.7% higher in the rhizosphere of plants growing in pyrene contaminated soil augmented with consortium. Sphingomonas, Sphingobium, Achromobacter, Ralstonia, Pseudoxanthomonas, Devosia, Cupriavidus, and the members of Sphingomonadeceae, Rhizobiaceae, Xanthomonadeceae, were dominant within Proteobacteria, where pyrene degradation was maximum. There was strong correlation between abundances of group of bacteria which were being affected with pyrene contamination or consortium treatment, and this effect was spread over for a group of bacteria, whose abundances were interdependent. Consequently, the treatment of PAH degrading consortium restored and recruited group of bacteria, which were otherwise depleted in presence of pyrene. Therefore, the application of consortium not only facilitated the degradation of pyrene, but also resulted in modulation of the bacterial community in the process of rhizosphere mediated biodegradation of pyrene in soil.