秸秆发酵中乳酸菌复合系SFC-2对杂菌的抑制作用

Antibacterial activity of lactic acid bacteria community SFC-2 used for fer-mentation of air-dried crop straws

摘要:

【目的】为探明秸秆发酵用乳酸菌复合系SFC-2对杂菌的抑制作用。【方法】从秸秆自然发酵体系中，利用平板划线法、纸片扩散法和变性梯度凝胶电泳（DGGE）筛选出13株菌作为研究该乳酸菌复合系抑菌作用的对象。【结果】（1）通过16S rDNA序列分析显示13株分离菌中9株菌的近缘种为Enterobacter cloacae、Klebsiella oxytoca、Bacillus cereus、Klebsiella pneumoniae、 Citrobacter freundii、Klebsiella terrigena、Citrobacter sp.，这些均为常见的致病菌或条件致病菌。（2）将筛选出的致病菌作为被测试菌株，用SFC-2的发酵上清液处理表明：SFC-2复合系的抑菌作用高于复合系分离的单一菌株和单一菌株人工组合的抑制作用。（3）SFC-2培养的14~48 h内动态检测结果表明：发酵上清液的有机酸含量有显著差异，但抑菌活性差异不显著；发酵上清液经热处理后抑菌活性不发生变化，蛋白酶 K处理后抑菌活性部分丧失。

Abstract:

[Objective] To evaluate the antibacterial activity of lactic acid bacteria community SFC-2 in fermented crop straw. [Methods] Total 13 isolates were obtained from spontaneous fermented rice straw by plating, paper diffusion and Denaturing Gradient Gel Electrophoresis. All these strains were used to determine the antibacterial activity of SFC-2. [Results] (1) Phylogenetic analysis of the 13 strains based on 16S rDNA gene sequence data indicated that 9 strains belong to Enterobacter cloacae, Klebsiella oxytoca, Bacillus cereus, Klebsiella pneumoniae, Citrobacter freundii, Klebsiella terrigena and Citrobacter sp., which were all common pathogens or opportunistic pathogens. (2) Indicating bacteria selected from the pathogens were used to detect antibacterial activity of SFC-2 cell-free culture supernatant. The results showed that: SFC-2 community had stronger antibacterial activity than isolated strains from SFC-2 community or man-made communities against indicating bacteria. (3) Antibacterial activities of seven different cell-free culture supernatants, which were extracted at intervals from the culture of SFC-2 community during 14-48 hours, were no obvious difference, but the content of organic acids were obvious differences during 14-48 hours; the antibacterial substances were stable after heating and sensitive partly to protease K.