关键词: 德国小蠊, 肠道细菌, 16S rDNA, 鉴定, 萎缩芽孢杆菌, 抗真菌

Abstract:

Objective To identify an intestinal bacterium BGI-17 isolated from German cockroaches (Blattella germanica) and to study its activity of anti-pathogenic fungi so as to clarify the composition and relationship of the intestinal flora in B. germanica. Methods The strain BGI-17 was identified according to the morphology and physiological and biochemical characteristics, and the phylogenetic tree was generated based on the sequence of 16S rDNA for molecular identification. The test for anti-Beauveria bassiana was conducted using the plate inhibition method and the growth of fungi was observed. Results The short, rod-shaped BGI-17 was positive for flagellum, Gram stain, spore stain and catalase. The 16S rDNA sequencing of BGI-17 showed that it shared 99% similarity with the published sequence of Bacillus atrophaeus strain, and both sequences constituted a branch in phylogenetic tree. The BGI-17 inhibited the growth of B. bassiana obviously and the fungal mycelium showed sick vacuolar enlargement, leading to leakage and mycelia protoplast rupture. Conclusion The BGI-17 was B.atrophaeus and it showed strong anti-insect pathogenic fungal activity that might contribute to withstanding the infection of pathogenic fungi.

Key words: Blattella germanica, Intestinal flora, 16S rDNA, Identification, Bacillus atrophaeus, Anti-fungal activity