高效降解棉酚菌株的分离鉴定及诱变选育

作为一种蛋白资源, 棉籽粕因其含有毒素——游离棉酚限制了其在饲料工业中的应用。为获得能高效降解棉籽粕中棉酚的菌株, 以醋酸棉酚为唯一碳源培养基从16份样品中筛选出一株高效降解棉酚菌株(Y-2), 经生理生化及18S rDNA鉴定为Pichia guilliermondii, 此菌种为非致病酵母, 且首次报道用于棉酚的降解, 在工业生产中具有潜在的应用前景。通过紫外诱变获得一株棉酚降解率更高的突变株YUV-51。通过对突变株YUV-51发酵温度、时间及接种量的初步优化, 获得其固态发酵优化条件: 30 °C培养48 h, 接种量0.025 g湿菌体/g棉籽粕, 初始水分含量50%。为避免游离棉酚在前处理中大量降解棉籽粕, 不进行湿热处理, 经接种发酵后脱毒率可达到58%。这使微生物脱毒在实际生产中应用成为可能。

Isolation, identification and mutation breeding of high gossypol detoxification strain

As a protein resource, only a little of cottonseed meal was used in feed industry due to the presence of toxin, gossypol. To obtain strains for gossypol detoxification, 16 soil samples were collected from China and 144 strains were isolated. Among them, a strain (Y-2) possess gossypol detoxification markedly. The strain Y-2 was identified as Pichia guilliermondii by traditional and molecular genetic identification. This strain was non-pathogenic yeast, and was first reported used on degradation of gossypol. Mutant YUV-51 with the highest detoxification was obtained by UV mutation. The detoxification rate of gossypol was up to 58% under optimized culture conditions: inoculation of 0.025g wet cell/g cottonseed meal, 30 °C, initial moisture content of solid substrate 50%, 48 h. Moreover, to avoid degradation of a large part of free gossypol before the fermentation, a great lot of energy could be saved with no heat-moisture treatment.