一株黄曲霉拮抗菌的筛选、鉴定及特性研究

为获得拮抗黄曲霉和降解黄曲霉毒素的生物防治菌株,以烟台黄曲霉污染区域土壤为材料,采用稀释分离法和琼脂扩散法,筛选到一株对黄曲霉有抑制作用且可降解黄曲霉毒素的菌株Y-17-3。根据菌株的形态学特征、生理生化试验结合16S rDNA基因序列分析和系统发育树构建,确定菌株 Y-17-3 为空气芽孢杆菌(Bacillus aerius)。该菌株发酵液经硫酸铵沉淀的抗菌活性及稳定性试验,发现70%饱和硫酸铵沉淀的蛋白粗提物抑制黄曲霉活性最强,可降低黄曲霉孢子的萌发率,抑制菌丝的生长和菌丝球的形成,且该蛋白粗提物对温度、pH值和蛋白酶敏感。菌株Y-17-3能够降解黄曲霉毒素B₁,培养6 d时的降解率达90%。综上,所分离的空气芽孢杆菌Y-17-3菌株能够通过产生拮抗蛋白来抑制黄曲霉生长,且具有较强的黄曲霉毒素降解能力,在农业生物防治领域具有一定的应用前景。

Screening,Identification and Characterization of Antagonistic Bacteria Against Aspergillus flavus

To obtain bio-control bacteria that can effectively suppress the growth of Aspergillus flavus and degrade the aflatoxin, the antagonistic strain Y-17-3 was screened by the agar diffusion method from the soil contaminated with A. flavus in Yantai. The strain Y-17-3 was identified to be Bacillus aerius based on the morphological characteristics, physiological and biochemical experiments, and the 16S rDNA gene sequence analysis followed by constructing phylogenetic tree. The crude protein extract precipitated at 70% saturated ammonium sulfate from the culture supernatant of strain Y-17-3 showed higher activity against A. flavus 3.2890. The spore germination rate of A. flavus 3.2890 treated with protein precipite was greatly reduced This active ingredient could inhibit the growth of mycelium and the formation of mycelium ball. The crude protein extract was sensitive to temperature, pH and protease. It could degrade aflatoxin B₁ by 90% after incubation at 37℃ for 6 d. The results showed that the strain B. aerius Y-17-3 isolated in this study can produce antagonistic proteins which inhibit the growth of A. flavus and was capable to degrade aflatoxins B₁ degradation. Therefore, this strain has the potential to be applied in the field of agricultural biological control.