Zjalic Slaven, Reverberi Massimo, Ricelli Alessandra, Mario Granito Vito, Fanelli Corrado, Adele Fabbri Anna
Department of Plant Biology, L.go Cristina di Svezia, 24, 00165-Roma, Italy.
Int J Food Microbiol. 2006 Apr 1;107(3):243-9. doi: 10.1016/j.ijfoodmicro.2005.10.003. Epub 2005 Dec 6.
The genotoxic, mutagenic and cancerogenic aflatoxins produced by Aspergillus parasiticus are not yet efficiently controlled besides the increasing researches on this topic. Aflatoxin production by A. parasiticus is related to oxidative stress and some antioxidants can inhibit their production. Some basidiomycetes as Trametes versicolor used as "healing mushrooms" present beta-glucans and glycoproteins which are responsible for the stimulation of the host immune response. In this work T. versicolor culture filtrates, from different isolates, have been tested on A. parasiticus cultures to assay their inhibiting effect on aflatoxin production. Filtrates from T. versicolor were lyophilised and exopolysaccharides and glycoproteins were extracted by subsequent steps and added (2% w/v) to liquid cultures of a toxigenic A. parasiticus strain. Fungal growth and aflatoxins production by A. parasiticus were analysed both in filtrates and in mycelia and no interference on the output of toxins from mycelia was evidenced. Furthermore antioxidant capacity (by crocin test) of the T. versicolor extracts was analysed. All the strains assayed are able to inhibit the toxin production from 40% to above 90% in liquid cultures as well as in maize and wheat seeds inoculated with A. parasiticus. Antioxidant activity and beta-glucans amount in T. versicolor extracts showed a close relationship with aflatoxin inhibition ability and demonstrated that beta-glucans could be involved in aflatoxin inhibition. Molecular data indicate the almost complete inhibition of norA mRNA expression and a delay of aflR mRNA transcription. Filtrates and fractions from T. versicolor could be promising agents in the challenge against aflatoxins.
除了对该主题的研究不断增加外，寄生曲霉产生的具有基因毒性、致突变性和致癌性的黄曲霉毒素尚未得到有效控制。寄生曲霉产生黄曲霉毒素与氧化应激有关，一些抗氧化剂可以抑制其产生。一些作为“药用蘑菇”的担子菌，如云芝，含有β-葡聚糖和糖蛋白，它们负责刺激宿主免疫反应。在这项工作中，对来自不同分离株的云芝培养滤液进行了测试，以检测其对寄生曲霉培养物中黄曲霉毒素产生的抑制作用。将云芝的滤液冻干，通过后续步骤提取胞外多糖和糖蛋白，并将其（2% w/v）添加到产毒寄生曲霉菌株的液体培养物中。分析了寄生曲霉在滤液和菌丝体中的真菌生长及黄曲霉毒素产生情况，未发现对菌丝体毒素产量有干扰。此外，还分析了云芝提取物的抗氧化能力（通过藏红花素试验）。所有测试菌株在液体培养物以及接种了寄生曲霉的玉米和小麦种子中，都能将毒素产生抑制40%至90%以上。云芝提取物中的抗氧化活性和β-葡聚糖含量与黄曲霉毒素抑制能力密切相关，表明β-葡聚糖可能参与了黄曲霉毒素的抑制过程。分子数据表明norA mRNA表达几乎完全受到抑制，aflR mRNA转录延迟。云芝的滤液和组分可能是对抗黄曲霉毒素的有前景的试剂。
