土壤中可编码乌头酸异构酶的芽胞杆菌菌株筛选及鉴定

【目的】以芽胞杆菌(Bacillus)为筛选对象,分离土壤中可编码乌头酸异构酶(aconitate isomerase,AI)的革兰氏阳性(Gram positive,G+)菌株,以丰富对AI分布的科学认识,为其生物学功能研究奠定理论与材料基础。【方法】采用土样高温预处理法、含反式乌头酸(trans-aconitic acid,TAA)唯一碳源的ACO固体平板培养法,结合16S rDNA基因序列同源性分析,筛选能够编码AI的芽胞杆菌目的菌株。【结果】共分离得到22株能够利用TAA碳源的细菌菌株,成功鉴定了其中的16株,分别为巨大芽胞杆菌(Bacillus megaterium) 2株,阿氏芽胞杆菌(Bacillus aryabhattai) 7株,短小芽胞杆菌(Bacillus pumilus) 1株,未鉴定到种的芽胞杆菌(Bacillus sp.) 6株;且它们所含AI编码基因与已知AI基因在序列上存在差异。【结论】首次证明可编码AI的芽胞杆菌细菌种类具有多样性,暗示G+细菌广泛编码AI的可能性,更新了AI几乎只在G–细菌中分布的观点,为后续深入挖掘AI基因及其生物学功能研究提供更多可用微生物资源。

Isolation and identification of soil Bacillus strains that encode aconitate isomerase

Objective] Purpose of this work was to specifically screen the Gram positive (G⁺) bacteria of Bacillus that could encode the aconitate isomerase (AI) enzyme, to enrich our understanding of the distribution of AI and to provide theoretical and material basis for further research. Methods] Through heat pretreatment of soil sample, plate cultivation by using ACO solid medium containing trans-aconitic acid (TAA) as the sole carbon source and the 16S rDNA sequences homologous analysis, the Bacillus target strains that encode AI can be isolated. Results] We totally isolated 22 bacterial strains that could utilize TAA carbon from the ACO plate, and 16 of which were successfully classified as:2 strains of Bacillus megaterium, 7 strains of Bacillus aryabhattai, one Bacillus pumilus strain, and 6 undetermined Bacillus sp. strains; besides, we found that the AI-coding genes of these 16 Bacillus isolates were different from the already cloned ones in DNA sequence. Conclusion] The species diversity of Bacillus bacteria encoding AI enzyme is rich, indicating the encoding ability in more G⁺ bacteria and updating the old opinion that considered AI distribution mainly in G^- hosts. Our research provided available microbial resource for further studies on the identification of AI gene as well as its biological significance.