Branà Maria Teresa, Cimmarusti Maria Teresa, Haidukowski Miriam, Logrieco Antonio Francesco, Altomare Claudio
Institute of Sciences of Food Production, National Research Council of Italy, Bari, Italy.
Department of Economics, University of Foggia, Foggia, Italy.
PLoS One. 2017 Aug 3;12(8):e0182574. doi: 10.1371/journal.pone.0182574. eCollection 2017.
Aflatoxin B1 (AFB1) is the most harmful mycotoxin that occurs as natural contaminant of agricultural commodities, particularly maize. Practical solutions for detoxification of contaminated staples and reduction of agricultural wastes are scarce. We investigated the capability of the white-rot and edible fungus Plerotus eryngii (king oyster mushroom) to degrade AFB1 both in vitro and in a laboratory-scale mushroom cultivation, using a substrate similar to that routinely used in mushroom farms. In malt extract broth, degradation of AFB1 (500 ng/mL) by nine isolates of P. eryngii ranged from 81 to 99% after 10 days growth, and reached 100% for all isolates after 30 days. The growth of P. eryngii on solid medium (malt extract-agar, MEA) was significantly reduced at concentrations of AFB1 500 ng/mL or higher. However, the addition of 5% wheat straw to the culture medium increased the tolerance of P. eryngii to AFB1 and no inhibition was observed at a AFB1 content of 500 ng/mL; degradation of AFB1 in MEA supplemented with 5% wheat straw and 2.5% (w/v) maize flour was 71-94% after 30 days of growth. Further, AFB1 degradation by P. eryngii strain ITEM 13681 was tested in a laboratory-scale mushroom cultivation. The mushroom growth medium contained 25% (w/w) of maize spiked with AFB1 to the final content of 128 μg/kg. Pleurotus eryngii degraded up to 86% of the AFB1 in 28 days, with no significant reduction of either biological efficiency or mushroom yield. Neither the biomass produced on the mushroom substrate nor the mature basidiocarps contained detectable levels of AFB1 or its metabolite aflatoxicol, thus ruling out the translocation of these toxins through the fungal thallus. These findings make a contribution towards the development of a novel technology for remediation of AFB1- contaminated corn through the exploitation of the degradative capability of P. eryngii and its bioconversion into high nutritional value material intended for feed production.
黄曲霉毒素B1（AFB1）是最具危害性的霉菌毒素，作为农产品尤其是玉米的天然污染物而存在。针对受污染主食进行解毒以及减少农业废弃物的切实可行的解决方案稀缺。我们研究了白腐食用菌杏鲍菇在体外以及实验室规模的蘑菇栽培中降解AFB1的能力，使用的基质类似于蘑菇农场常规使用的基质。在麦芽提取物肉汤中，9株杏鲍菇分离株在生长10天后对AFB1（500纳克/毫升）的降解率在81%至99%之间，30天后所有分离株的降解率均达到100%。在AFB1浓度为500纳克/毫升或更高时，杏鲍菇在固体培养基（麦芽提取物琼脂，MEA）上的生长显著降低。然而，向培养基中添加5%的麦秸可提高杏鲍菇对AFB1的耐受性，在AFB1含量为500纳克/毫升时未观察到抑制作用；在添加5%麦秸和2.5%（w/v）玉米粉的MEA中，生长30天后AFB1的降解率为71%至94%。此外，在实验室规模的蘑菇栽培中测试了杏鲍菇菌株ITEM 13681对AFB1的降解情况。蘑菇生长培养基含有25%（w/w）添加了AFB1的玉米，最终含量为128微克/千克。杏鲍菇在28天内降解了高达86%的AFB1，生物效率和蘑菇产量均未显著降低。蘑菇基质上产生的生物量以及成熟的子实体中均未检测到可检测水平的AFB1或其代谢产物黄曲霉毒素醇，因此排除了这些毒素通过真菌菌体转运的可能性。这些发现有助于开发一种新技术，通过利用杏鲍菇的降解能力并将其生物转化为用于饲料生产的高营养价值材料，来修复受AFB1污染的玉米。
