1株抗真菌贝莱斯芽孢杆菌(Bacillus velezensis)lut-Y1的鉴定及抑菌活性研究

Identification and Bacteriostatic Activity Analysis of an Antifungal Bacillus velezensis lut-Y1

【目的】探究1株来自枸杞果实的贝莱斯芽孢杆菌lut-Y1的生长特性及抑菌活性,为微生态制剂的开发和应用提供参考。【方法】通过形态观察和16S rDNA基因测序分析对该菌株进行鉴定;测定该菌株生长曲线及最适pH、碳源、氮源及盐耐受度;采用平板对峙法观察该菌株对链格孢菌(Alternaria alternate)、小麦根腐离蠕孢(Bipolaris sorokiniana)和小孢壳二孢(Ascochyta leptospora)的颉颃作用,并分析该菌株发酵液对3种病原真菌的抑菌活性。【结果】lut-Y1菌株在LB、NA和PDA培养基上均生长良好。根据形态和16S rDNA基因序列特征将lut-Y1菌株鉴定为贝莱斯芽孢杆菌(Bacillus velezensis)。在LB液体培养基中,lut-Y1菌株在0~3 h为迟滞期,3~18 h为对数期,18~62 h为稳定期,62 h后进入衰亡期;最适pH为7.0,最适碳源和氮源分别为蔗糖和蛋白胨,对NaCl的耐受量不超过2.0 g/L。lut-Y1菌株对链格孢菌有明显的颉颃作用,对小麦根腐离蠕孢和小孢壳二孢的颉颃作用较弱。对峙平板的两菌交界处,链格孢菌基内菌丝细弱、弯曲;小麦根腐离蠕孢基内菌丝细胞壁被破坏,有泡状突起。发酵液添加量为25%时生长圈直径分别缩小72.80%和83.24%。【结论】贝莱斯芽孢杆菌lut-Y1具有较好的抑菌活性,可为开发以芽孢杆菌为主要活性成分的微生态制剂提供材料。

【Objective】The aim of this study was to investigate the growth characteristics and antibacterial activity of a strain of Bacillus velezensis lut-Y1 from Lycium barbarum L.,and provide a reference for the development and application of microecologics.【Method】The strain was identified by morphological observation and 16S rDNA gene sequencing.The growth curve,optimum pH,carbon source,nitrogen source and salt tolerance of the strain were measured.The antagonistic effects of the strain on Alternaria alternate,Bipolaris sorokiniana and Ascochyta leptospora were observed by plate confrontation method.The antibacterial activity of the fermentation broth against three kinds of pathogenic fungi was analyzed.【Result】The lut-Y1 strain grew well on LB,NA and PDA medium.The strain lut-Y1 was identified as Bacillus velezensis based on its morphology and 16S rDNA gene sequence characteristic.In LB liquid medium,lut-Y1 strain showed a retardation stage from 0 to 3 h,a logarithmic stage from 3 to 18 h,a stable stage from 18 to 62 h,and a decline stage after 62 h.The optimal pH was 7.0,the optimal carbon and nitrogen sources were sucrose and peptone,respectively,and the tolerance to NaCl was no more than 2.0 g/L.lut-Y1 strain had obvious antagonistis effect on Alternaria alternate,but had weak antagonistic effect on Bipolaris sorokiniana and Ascochyta leptospora.At the junction of the two bacteria in the standoff plate,the mycelium in the base of Alternaria alternate was thin and curved.The mycelium cell wall was destroyed and bulbous protrusions were found in the base of Bipolaris sorokiniana.When the fermentation broth was added by 25%,the growth circle diameter were decreased by 72.80%and 83.24%,respectively.【Conclusion】Bacillus velezensis lut-Y1 had good antibacterial activity,which could provide materials for the development of microecological preparations and biological pesticides with Bacillus as the main active ingredient.