苏云金芽胞杆菌分离过程中无晶体芽胞杆菌的分析

Analysis of Bacillus without Protein Crystals during Isolation of Bacillus thuringiensis

本研究选择了在苏云金芽胞杆菌Bacillus thuringiensis(Bt)分离过程中发现的与Bt芽胞相似、没有伴胞晶体的8株芽胞杆菌,对其种属、质粒等生物学特性和杀虫活性进行了初步研究。对分离菌株所产芽胞进行形态观察及质粒图谱分析,发现其与Bt相似;但肽指纹图谱分析和16SrDNA聚类研究表明所分离菌株与蜡样芽胞杆菌B.cereus(Bc)匹配最高;杀虫活性测定表明这8株菌对猿叶甲Colaphellus bowringi幼虫均无毒杀作用,而15-3、W23-1和W25-3 3个菌株及其培养上清液对小菜蛾Plutella xylostella幼虫有一定的杀虫活性,说明它们能产生活性物质。这些结果说明在Bt菌株的分离过程中要对无晶体菌株加以重视,其含有的活性物质具有潜在的研究和利用价值。

Three aspects including species,biological characteristic and insecticidal activity of eight strains of Bacillus spp.with spores similar to B.thuringiensis and without protein crystals were analyzed.Both spores morphology and plasmid pattern of these Bacillus spp.showed similarity with those of B.thuringiensis,however,assay of Peptide Mass Fingerprinting and species identification by 16S rDNA indicated they shared the highest homology with B.cereus. Bioassay results of the eight strains against larvae of Colaphellus bowringi and Plutella xylostella showed that all the strains were not toxic to C.bowringi, while both bacterial cell and supernatant of strains 15-3,W23-1 and W25-3 were insecticidal to P.xylostella.These bioassay results suggested insecticidal substance was produced in these strains.The results indicated that the strains without protein crystals should not be neglected and abandoned during isolation of B.thuringiensis.Insecticidal substances produced by these strains are potential to be exploited.