Isolation, Characterization And PM Degrading Enzyme Production Of Organophosphorus Pesticide Degrading Fungi

The extensive use of Organophosphorus Pesticides (OPs) made them common environmental pollutants in environments, and posed huge potential hazards to human health. It was quite necessary to remove OPs residue, microbial and its degrading enzymes deemed the most influential and significant cause of OPs removal, which had great application prospect.Three fungi JMUPMD-1, JMUPMD-2, JMUPMD-3 capable of growing with parathion-me thyl (PM) as the sole phosphorus source newly isolated from the OPs-polluted soil. They were identified based on rDNA ITS sequences analysis, morphological, physiological and biochemical characterisitics. Optimized PM degrading enzyme production of JMUPMD-3 through flask culture, then fermented in 7 L bioreactor and analysised its fermentation dynamics.JMUPMD-1's sequences of rDNA ITS was 99% similar to Candida blankii, also its morphologies, physiological and biochemical characterisitics were identical with Candida blankii, consequently, it was identified as Candida blankii. JMUPMD-2's colonic and microscopic morphologies were identical with and its sequences of rDNA ITS was 99% similar to Apspergillus oryzae. Consequently, it was identified as Aspergillus oryzae. JMUPMD-3's sequences of rDNA ITS was 99% similar to Talaromyces flavus, and its morphologies were identical with Talaromyces flavus, thus, it was identified as Aspergillus oryzae (conidia state Penicillium vermiculatum Dangeard).Three fungi's Parathion-methyl (PM) degradeing enzyme were endoenzyme, and T. flavus JMUPMD-3's ability of producing enzyme was best. The optimum medium and condition of fla sk-fermentation PM degrading enzyme were: sucrose 19.0 g/L, yeast extract 3.2 g/L, MgSO4·7H₂O 0.5 g/L, KCl 0.5 g/L, FeSO4·7H₂O 0.018 g/L, Triton X-100 2% (v/v), PM missible oil 0.2% (v/v), initial pH of the medium 8.0, culture temperature 34℃. The activity of PM degrading enzyme in 7 L bioreactor was 46.1 U/L before optimization, using the optimum medium and conditions, PM degrading enzyme activities of second batch 7 L-bioreator fermention reached to 127.1 U/L, which increased by 183% compared to first batch. The third batch without Triton X-100, controlled pH 6.0, the biomass increased by 3.2 g/L, the supreme enzyme activities remained stable, and stationary phase postponed. Kinetic analysis showed that the production of PM degrading enzyme was coupling to the biomass growth from 24 h to 56 h and related to the consumption of PM, but did not affect the consumption of PM. PM degrading enzyme could degrade dichlorvos effectively, it was a broad-spectrum degrading enzyme.Isolated three fungi capable of degrading OPs, and rare reports about Candida blankii and Talaromyces flavus degrading OPs. So, it provided new resources of OPs degrading fungus. PM degrading enzyme production optimization and 7 L-bioreator fermention tries of T. flavus JMUPMD-3 laid a well foundation for further improving enzyme activities. Keywords: Organophosphorus Pesticides, Microbiological degradation, Candida blankii,...