Protection of PSI and PSII complexes of wheat from toxic effect of anthracene by Bacillus subtilis (NCIM 5594).

Contamination of polycyclic aromatic hydrocarbons (PAHs) in environment indicates a serious problem to the present era. These are carcinogenic and mutagenic compounds and pose a potential risk to photosynthetic organisms. The present study illustrates the protection of Photosystem I and Photosystem II complexes of wheat plant by Bacillus subtilis (NCIM 5594) from toxic effects of anthracene (ANT). Initially, Chl a fluorescence induction curve measurement revealed declined J-I and I-P phase in ANT-treated plants. Efficiency of light absorption, trapping, and electron transport was reduced in ANT-treated plants, while in ANT + Bacillus subtilis (NCIM 5594)-treated plants value of these parameters was restored. Effect of ANT and ANT + Bacillus subtilis (NCIM 5594) on energy conversion of Photosystem I and Photosystem II was measured. Quantum yield of Photosystem I (YI) and Photosystem II (YII) was decreased in the presence of ANT, while these values were recovered in ANT + Bacillus subtilis (NCIM 5594)-treated plants. Reduction in Y(II) was associated with an increase in non-regulated energy dissipation NO. Likewise the reduction of Y(I) was induced due to donor-side and acceptor-side limitation of Photosystem I caused by toxic effect of ANT. Toxic effects of ANT on electron transport rate (ETR and ETR) were found to be reduced in ANT + Bacillus subtilis (NCIM 5594)-treated plants. Activation of Cyclic electron flow around Photosystem I in ANT-treated plants was recovered by bacteria. It was concluded that toxic effect of ANT on Photosystem I and Photosystem II complexes was recovered by Bacillus subtilis (NCIM 5594) strain, and thus it is useful strain for crop improvement in ANT-polluted soil.