食源米曲霉菌株的分离及其降解高效氯氰菊酯和3-苯氧基苯甲酸的特性研究

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

摘要:

[目的] 通过研究不同食源米曲霉菌株对高效氯氰菊酯（beta-cypermethrin，β-CP）及其必经代谢产物3-苯氧基苯甲酸（3-phenoxybenzoic acid，3-PBA）的降解特性，了解不同菌株的降解共性及差异性，为农副产品和发酵食品的农残减除提供理论基础和食品用安全微生物资源。[方法] 以发酵食品为菌源，通过形态学鉴定、ITS测序和菌株产黄曲霉毒素B1（AFB1）的测定筛选鉴定米曲霉菌株，采用高效液相色谱法（HPLC）、气相色谱-质谱法（GC-MS）、液相色谱-质谱法（LC-MS）对米曲霉模式菌株RIB40（保藏编号：ATCC 42149）、米曲霉M4（保藏编号：CGMCC 11645）和鉴定获得的米曲霉菌株的β-CP和3-PBA降解特性进行研究。[结果] 鉴定获得15株不产AFB1的食源米曲霉，17株米曲霉在马铃薯液体培养基（PD）中振荡培养5 d，对50 mg/L的β-CP降解率为19.33%-50.29%不等，检测到降解产物3-PBA，对50 mg/L的3-PBA降解率为45.59%-99.67%不等；分别在添加50 mg/L β-CP和3-PBA的无机盐培养基（MM）中振荡培养5 d，米曲霉菌株均未生长，对β-CP和3-PBA无降解；在富集培养基（GM）中振荡培养2 d，对100 mg/L的3-PBA转化或降解率为69.28%-99.58%不等，检测到3-苯氧基苄醇（3-PBlc）和羟基-3-苯氧基苯甲酸（HO-3-PBA）。[结论] 食源米曲霉具有共代谢降解β-CP和3-PBA的共性，3-PBA为β-CP降解中间产物，米曲霉对3-PBA普遍具有较高的降解率。在3-PBA降解初期，米曲霉可将其短暂还原生成毒性相对较低的3-PBlc，同时，3-PBA逐渐羟基化生成水溶性更强的HO-3-PBA参与下游降解。

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.