Diminishing toxicity of pyrene on photosynthetic performance of soybean using

Abstract

Polycyclic aromatic hydrocarbons are persistent organic pollutants causing serious environmental problems, being toxic to plants and difficult to remediate. Pyrene is one such extremely dangerous compound that is toxic for the environment. This study suggests the use of Bacillus subtilis (National Collection of Industrial Microorganisms [NCIM] 5594) to overcome inhibitory effects of pyrene on soybean photosynthesis. The toxicity of pyrene to soybean was evident from a significant decrease in seed germination parameters, photosynthetic performance and biomass during growth of soybean in pyrene contaminated soil. Efficiency of performance index, light absorption, trapping and electron transport were reduced in plants grown in pyrene contaminated soil while significant recovery in these parameters was observed in plants grown in pyrene + B. subtilis treated soil. Activity levels of dehydrogenase and lipase enzymes significantly recovered in pyrene + B. subtilis treated soil. After extraction of pyrene from soil and soybean plant, concentration of pyrene was lowered in pyrene + B. subtilis treated soil and plants. These findings suggest efficient degradation of pyrene by B. subtilis. About 70% degradation of pyrene was achieved in soil using B. subtilis; thus it is a useful strain for crop improvement in pyrene polluted soil.