Degradation properties of beta-cypermethrin and 3-phenoxybenzoic acid by food-derived Aspergillus oryzae strains

Abstract:

[Objective] Here we studied the degrading properties of different food-derived Aspergillus oryzae strains to beta-cypermethrin (β-CP) and 3-phenoxybenzoic acid (3-PBA), so as to lay a theoretical foundation as well as provide potential microbial food cultures resources for pesticides reduction towards agricultural by-products and fermented foods.[Methods] Identified by morphology, ITS sequencing and production of aflatoxin B1 (AFB1), fifteen A. oryzae strains were screened from fermented foods. A. oryzae RIB40 (collection number:ATCC 42149) and A. oryzae M4 (collection number:CGMCC 11645), together with isolated strains, were determined for β-CP and 3-PBA degrading characteristics via HPLC-UV, GC-MS as well as LC-MS.[Results] After 5 days of shaking culture in potato dextrose broth (PD), degradation rates of 50 mg/L β-CP by seventeen strains varied from 19.33% to 50.29% and 50 mg/L 3-PBA from 45.59% to 99.67%, with 3-PBA been detected during β-CP degradation. Cultured in mineral basal medium (MM) for 5 days, strains failed to grow and no removal of β-CP or 3-PBA was observed. In contrast, seventeen strains could grow in glucose enrichment medium (GM) shaking culture, and 2 days later, conversion or degradation rates of 100 mg/L 3-PBA ranged from 69.28% to 99.58%, of which systems detected 3-phenoxybenzyl alcohol (3-PBlc) and hydroxy-3-phenoxybenzoic acid (HO-3-PBA).[Conclusion] A. oryzae strains exhibit the common nature of co-metabolizing β-CP and its intermediate 3-PBA, with high-efficiency 3-PBA degradation performance. Moreover, A. oryzae strains can briefly transform 3-PBA into 3-phenoxybenzyl alcohol (3-PBlc) which has lower toxicity at initial stage. Meanwhile, 3-PBA is hydroxylated to yield HO-3-PBA that shows better water-solubility, subsequently into further metabolism.

Key words:microbial food cultures;Aspergillus oryzae;biodegradation;beta-cypermethrin;3-phenoxybenzoic acid