Das Arijit, Bhattacharya Sourav, Palaniswamy Muthusamy, Angayarkanni Jayaraman
Department of Microbiology, Karpagam University, Coimbatore, 641021, Tamil Nadu, India,
World J Microbiol Biotechnol. 2014 Aug;30(8):2315-24. doi: 10.1007/s11274-014-1657-5. Epub 2014 Apr 28.
Aflatoxin B1 (AFB1) is a highly toxic fungal metabolite having carcinogenic, mutagenic and teratogenic effects on human and animal health. Accidental feeding of aflatoxin-contaminated rice straw may be detrimental for ruminant livestock and can lead to transmission of this toxin or its metabolites into the milk of dairy cattle. White-rot basidiomycetous fungus Pleurotus ostreatus produces ligninolytic enzymes like laccase and manganese peroxidase (MnP). These extracellular enzymes have been reported to degrade many environmentally hazardous compounds. The present study examines the ability of P. ostreatus strains to degrade AFB1 in rice straw in the presence of metal salts and surfactants. Laccase and MnP activities were determined spectrophotometrically. The efficiency of AFB1 degradation was evaluated by high performance liquid chromatography. Highest degradation was recorded for both P. ostreatus MTCC 142 (89.14 %) and P. ostreatus GHBBF10 (91.76 %) at 0.5 µg mL(-1) initial concentration of AFB1. Enhanced degradation was noted for P. ostreatus MTCC 142 in the presence of Cu(2+) and Triton X-100, at toxin concentration of 5 µg mL(-1). P. ostreatus GHBBF10 showed highest degradation in the presence of Zn(2+) and Tween 80. Liquid chromatography-mass spectrometric analysis revealed the formation of hydrated, decarbonylated and O-dealkylated products. The present findings suggested that supplementation of AFB1-contaminated rice straw by certain metal salts and surfactants can improve the enzymatic degradation of this mycotoxin by P. ostreatus strains.
黄曲霉毒素B1（AFB1）是一种剧毒的真菌代谢产物，对人类和动物健康具有致癌、致突变和致畸作用。意外投喂受黄曲霉毒素污染的稻草可能对反刍家畜有害，并可能导致这种毒素或其代谢产物传播到奶牛的牛奶中。白腐担子菌平菇能产生漆酶和锰过氧化物酶（MnP）等木质素分解酶。据报道，这些细胞外酶能降解许多对环境有害的化合物。本研究考察了平菇菌株在金属盐和表面活性剂存在下对稻草中AFB1的降解能力。通过分光光度法测定漆酶和MnP的活性。采用高效液相色谱法评价AFB1的降解效率。在AFB1初始浓度为0.5μg mL(-1)时，平菇MTCC 142（89.14%）和平菇GHBBF10（91.76%）的降解率最高。在毒素浓度为5μg mL(-1)时，在Cu(2+)和Triton X-100存在下，平菇MTCC 142的降解增强。平菇GHBBF10在Zn(2+)和吐温80存在下显示出最高的降解率。液相色谱-质谱分析揭示了水合、脱羰和O-脱烷基产物的形成。目前的研究结果表明，用某些金属盐和表面活性剂补充受AFB1污染的稻草可以提高平菇菌株对这种霉菌毒素的酶促降解。
