Polyaromatic hydrocarbon (PAH) degradation potential of a new acid tolerant, diazotrophic P-solubilizing and heavy metal resistant bacterium Cupriavidus sp. MTS-7 isolated from long-term mixed contaminated soil

Abstract

An isolate of Cupriavidus (strain MTS-7) was identified from a long-term PAHs and heavy metals mixed contaminated soil with the potential to biodegrade both LMW and HMW PAHs with added unique traits of acid and alkali tolerance, heavy metal tolerance, self-nutrient assimilation by N fixation and P solubilization. This strain completely degraded the model 3 (150 mg L−1 Phe), 4 (150 mg L−1 Pyr) and 5 (50 mg L−1 BaP) ring PAHs in 4, 20 and 30 days, respectively. It could mineralize 90–100% of PAHs (200 mg L−1 of Phe and Pyr) within 15 days across pH ranging from 5 to 8 and even in the presence of toxic metal contaminations. During biodegradation, the minimum inhibitory concentrations were 5 (Cu2+) and 3 (Cd2+, Pb2+, Zn2+) mg L−1 of the potentially bioavailable metal ions and over 17 mg L−1 metal levels was lethal for the microbe. Further, it could fix 217–274 μg mL−1 of N and solubilize 79–135 μg mL−1 of P while PAHs degradation. MTS-7 as a superior candidate could be thus used in the enhanced bioaugmentation and/or phytoremediation of long-term mixed contaminated sites.