一株抑制烟草疫霉的耐受盐芽孢杆菌(Bacillus halotolerans)的分离、鉴定及全基因组测序分析

Isolation, identification, and whole genome sequencing of a Bacillus halotolerans strain inhibiting Phytophthora nicotianae

摘要:

【背景】 烟草黑胫病是由烟草疫霉侵染所引起的土传类病害，在我国烟草种植区内发病率高且病情严重，造成的产量损失巨大。【目的】 筛选对烟草黑胫病菌有拮抗作用的生防菌株，为烟草黑胫病的生物防治提供菌种资源。【方法】 采用稀释涂布平板法、平板对峙法筛选出对烟草疫霉(Phytophthora nicotianae)具有拮抗作用的菌株，借助DNBSEQ平台和PacBio平台对拮抗菌株进行全基因组测序，通过antiSMASH在线软件对拮抗菌株的次级代谢产物基因簇进行预测。【结果】 筛选分离出一株可以抑制烟草疫霉生长的耐受盐芽孢杆菌(Bacillus halotolerans) BY-S2。菌株BY-S2具有溶磷、产铁载体的能力，还对重金属铜具有一定的耐受能力。全基因组测序结果表明，菌株BY-S2基因组长度为4 058 008 bp，只有一条环形染色体，平均G+C含量为43.78%。antiSMASH共预测到次级代谢产物基因簇10个，其中5个与bacillaene、fengycin、bacillibactin、subtilosin A、bacilysin化合物合成相关基因簇完全一致。【结论】 耐受盐芽孢杆菌BY-S2对烟草疫霉具有拮抗作用，具有溶磷和产生铁载体的能力，具有5种已知的抑菌代谢物合成基因簇。

关键词:耐受盐芽孢杆菌;烟草黑胫病;促生作用;全基因组测序

Abstract:

[Background] Tobacco black shank is a soil-borne diseases caused by Phytophthora nicotianae. This disease exhibits a high incidence and severity in tobacco cultivation regions across China, leading to substantial yield losses. [Objective] To screen the strains with antagonistic activity against Phytophthora nicotianae and provide strain resources for the biocontrol of tobacco black shank. [Methods] The dilution-plate spreading method and the plate confrontation method were employed to screen the strains with antagonistic effects on Phytophthora nicotianae. Whole genome sequencing of the antagonistic strain was performed on the DNBSEQ and PacBio platforms, and antiSMASH online was used for the prediction of synthetic gene clusters of secondary metabolites. [Results] Bacillus halotolerans BY-S2, a strain capable of inhibiting the growth of P. nicotianae, was isolated. Strain BY-S2 exhibited phosphorus-solubilizing ability, siderophore- producing ability, and tolerance to copper. Whole genome sequencing revealed that the genome of strain BY-S2 was a circular chromosome with a length of 4 058 008 bp and the G+C content of 43.78%. A total of 10 synthetic gene clusters of secondary metabolites were predicted by antiSMASH, including 5 completely consistent with known gene clusters for the synthesis of bacillaene, fengycin, bacillibactin, subtilosin A, and bacilysin. [Conclusion] B. halotolerans BY-S2 exhibits antagonistic activity against P. nicotianae, has the ability to solubilize phosphate and produce siderophores, and carries 5 known gene clusters of secondary metabolites.

Key words:Bacillus halotolerans;tobacco black shank;growth-promoting effect;whole genome sequencing