疮痂链霉菌拮抗菌的筛选鉴定及特性研究

Screening, identification, and characterization of Streptomyces scabies antagonists

摘要:

由致病性链霉菌疮痂链霉菌(Streptomyces scabies)引起的疮痂病已成为威胁马铃薯产业可持续发展的重要瓶颈，以菌治菌是目前最为理想的措施。【目的】 筛选具有解磷功能的拮抗菌株，研究其对马铃薯疮痂病防控的增益效果，为研制复合功能菌剂提供候选菌种。【方法】 采用平板对峙和解磷试验筛选目标菌株，利用形态学观察、生理生化实验及16S rRNA基因测序确定其分类地位；通过盆栽和大田试验研究目标菌株对致病性链霉菌的抑制效果，并分析解磷功能对拮抗效果的增益。【结果】 获得4株对致病链霉菌具有明显拮抗作用的菌株，分别为BN4-4、BN4-5、BN5-2和YN17-2，经鉴定BN4-4、BN4-5为深褐芽孢杆菌(Bacillus atrophaeus)，BN5-2和YN17-2为枯草芽孢杆菌(Bacillus subtilis)，其中BN4-4和BN5-2具有较强的降解无机磷的能力。4株菌的盆栽试验相对防效分别为71.35%、38.70%、62.18%和36.22%，BN4-4和BN4-5的田间防效分别为69.07%和56.20%。4株菌对茄链格孢菌、尖孢镰孢菌、立枯丝核菌、大丽轮枝菌等植物病原菌具有明显的抑制效果，可耐受pH 1.0−13.0、1%−13% NaCl及80 ℃的高温环境，对阿维菌素、中生菌素、甲基硫菌灵、春雷霉素、多菌灵等生产上常用的杀菌剂不敏感。4株菌均可代谢产生吲哚乙酸(indole-3-acetic acid, IAA)，表现良好的促生增产效果。相比之下，具有解磷功能的BN4-4和BN5-2对疮痂链霉菌的抑制作用较对应的非解磷菌种更佳。【结论】 具有解磷功能的深褐芽孢杆菌BN4-4对致病性链霉菌具有良好防效，该菌株具有较好的广谱抗病性、热稳定性、耐盐碱、促生和定殖能力，对防控马铃薯疮痂病等农作物土传病害具有良好的前景。

Abstract:

Potato scab caused by Streptomyces scabies has become a bottleneck threatening the sustainable development of the potato industry. Using biocontrol strains to combat bacterial infections is considered an ideal approach. [Objective] We screened the phosphorus-solubilizing antagonistic strains of S. scabies and investigated their effects on the prevention and control of potato scab, aiming to provide candidate strains for the development of composite functional bacterial agents. [Methods] The target strains were screened by plate confrontation and phosphorus-solubilizing tests. Their taxonomic status was determined by morphological observation, physiological and biochemical tests, and 16S rRNA gene sequencing. Pot and field experiments were carried out to measure the inhibitory effects of the target strains on S. scabies, and the relationship between phosphorus-solubilizing function and antagonistic effect was analyzed. [Results] Four antagonistic strains BN4-4, BN4-5, BN5-2, and YN17-2, were screened out. Among them, BN4-4 and BN5-2 showed strong ability to degrade inorganic phosphorus. BN4-4 and BN4-5 were identified as Bacillus atrophaeus, while BN5-2 and YN17-2 as Bacillus subtilis. The pot experiments showed that the relative control effects of the four strains were 71.35%, 38.70%, 62.18%, and 36.22%, respectively. In the field experiments, BN4-4 and BN4-5 showed the control effects of 69.07% and 56.20%, respectively. The four strains exerted inhibitory effects on four plant pathogens: Alternaria solani, Fusarium oxysporum, Rhizoctonia solani, and Verticillium dahliae. The four strains showed tolerance to pH 1.0–13.0, NaCl concentration of 1%–13%, and high temperatures (up to 80 ℃). Furthermore, they were insensitive to commonly used fungicides such as avermectin, zhongshengmycin, thiophanate-methyl, kasugamycin, and carbendazim. All the four stains exhibited the ability to metabolize and produce indole-3-acetic acid (IAA), which has been shown to promote the growth and increase the yield of plants. Notably, strains BN4-4 and BN5-2 capable of solubilizing phosphorus exhibited stronger inhibitory effects on S. scabies than the non-phosphorus-solubilizing strains. [Conclusion] B. atrophaeus BN4-4 with phosphorus-solubilizing function demonstrated promising preventive effects against S. scabies. This strain demonstrated broad-spectrum disease resistance, thermal stability, salinity tolerance, plant growth-promoting effect, and colonizing ability, serving as a potential functional strain for preventing and controlling potato scab and other soil-borne diseases in crops.