一株枯草芽孢杆菌噬菌体Bac-S的生物学特性及全基因组序列分析

Biological characterization and genome sequence of a bacteriophage strain Bac-S infecting Bacillus subtilis

摘要:

【目的】枯草芽孢杆菌(Bacillus subtilis)施用于土壤可促进植物生长，但针对土壤中枯草芽孢杆菌噬菌体的研究鲜有报道，因此从土壤中分离出枯草芽孢杆菌噬菌体，并深入研究其生物学特性及基因组特征，不仅有助于枯草芽孢杆菌的实际应用，还能丰富枯草芽孢杆菌噬菌体相关生物信息库。【方法】以枯草芽孢杆菌SM13为宿主，从土壤中分离培养出一株噬菌体Bac-S，对其进行生物学特性测定、全基因组序列特征、基因功能注释和系统发育分析。【结果】透射电镜显示，噬菌体Bac-S头部直径约为43 nm，尾部极短无法测量；该噬菌体的最佳感染复数(multiplicity of infection, MOI)为0.1；一步生长曲线显示，潜伏期约为10 min，裂解量为30 PFU/cell；宿主谱广泛，能实现跨属侵染；测序结果显示其基因组长度为150 019 bp，G+C含量为42.6%；该噬菌体共有237个开放阅读框(open reading frames, ORFs)，BLASTn比对显示该噬菌体与NCBI数据库中其他芽孢杆菌噬菌体相似性较高。【结论】从土壤中分离出了一株具有潜伏期短、宿主谱广泛、耐受高温、不耐紫外光照射的特征枯草芽孢杆菌噬菌体，拓宽了对枯草芽孢杆菌噬菌体的认知。

Abstract:

[Objective] The application of Bacillus subtilis in soil can promote plant growth, while few studies have reported the bacteriophages infecting B. subtilis. Therefore, the isolation, biological characterization, and genome sequencing of bacteriophages infecting B. subtilis from soil will contribute to the application of B. subtilis and enrich the biological information of bacteriophages infecting B. subtilis. [Methods] B. subtilis SM13 was used as the host to isolate a bacteriophage strain Bac-S from soil. Biological characterization, whole genome sequencing, gene function annotation, and phylogenetic analysis were performed for this bacteriophage strain. [Results] Transmission electron microscopy showed that Bac-S had a head with the diameter of about 43 nm and a tail too short to be measured. The optimal multiplicity of infection of Bac-S was 0.1. The one-step growth curve showed that Bac-S had an incubation period of about 10 min and a burst size of 30 PFU/cell. Bac-S had a wide host spectrum and can infect hosts of different genera. The sequencing results showed that the genome of Bac-S was 150 019 bp, with the G+C content of 42.6% and 237 open reading frames (ORFs). The BLASTn comparison with the sequences in the NCBI database showed that Bac-S was similar to other bacteriophages infecting B. subtilis. [Conclusion] A bacteriophage strain infecting B. subtilis with a short incubation period, a wide host spectrum, tolerance to high temperature, and intolerance to UV light was isolated from soil. The biological and genetic characterization of this bacteriophage enriches our knowledge about the bacteriophages infecting B. subtilis.