Biodegradation of Benzo(a)pyrene by biofilm forming and plant growth promoting Acinetobacter sp. strain PDB4.

Polyaromatic Hydrocarbon (PAH) degrading bacteria were isolated from petroleum contaminated soil and studied for their ability to produce biofilm and attributes for plant growth promotion under PAH stress. The isolate Acinetobacter sp. PDB4 was selected based on its excellent ability to degrade of low molecular weight (anthracene) as well as high molecular weight [pyrene and benzo(a)pyrene (BaP)] PAHs. PDB4 resulted in high emulsification index and tendency to form biofilm under the stress of PAHs. Increase in concentration of PAH resulted in higher stress response as increases in release of glutathione-S-transferase. Moreover, degradation of BaP was quantified using HPLC and GC-MS analysis, which suggested 80.34% degradation of BaP by strain PDB4 after 21 days of incubation. Further, the isolate was found to be having plant growth promoting attributes, checked under the stress of PAH. Acinetobacter sp. PDB4 solubilized phosphate in vitro, and released 21μg∕ml of IAA after 96 h of incubation under PAH stress, in addition to 55% of siderophore activity after 120 h, suggesting it suitable for rhizoremediation applications.