疮痂链霉菌拮抗菌的筛选及发酵条件优化

Screening and fermentation condition optimization of Streptomyces scabies antagonists

摘要:

近年来，由致病性链霉菌引起的马铃薯疮痂病呈逐年加重趋势，已成为亟待破解的产业难题。筛选抑菌效果好、适应性广的拮抗菌，是实现该病有效防控的主要措施。本研究采用平板对峙试验筛选到3株对疮痂链霉菌(Streptomyces scabies)有较好抑菌效果的拮抗菌DXT2-4、T2-1和21-14，依据形态特征、生理生化特性以及16S rRNA基因序列，鉴定3株菌分别为高地芽孢杆菌(Bacillus altitudinis)、沙福芽孢杆菌(Bacillus safensis)和短小芽孢杆菌(Bacillus pumilus)，对马铃薯疮痂病盆栽防效依次为68.83%、48.57%和57.14%；3株菌在内蒙古自治区呼伦贝尔市田间小区试验防效分别为59.48%、34.58%和51.75%；广东省惠州市田间防效分别为55.14%、36.05%和49.05%。3株菌均可在pH 1.0–13.0、NaCl含量为1%–11%的培养基中正常生长，对立枯丝核菌、大丽轮枝菌、茄链格孢菌和尖刀镰孢菌有抑制效果；DXT2-4、T2-1和21-14的吲哚乙酸(indole-3-acetic acid, IAA)产量分别为2.23、1.11和1.67 mg/L，其中DXT2-4和21-14具有较强的溶磷能力。菌株DXT2-4发酵的最佳碳、氮源和无机盐分别为2.00%糖蜜+2.00%玉米淀粉、2.00%豆饼粉和0.3% MgSO₄·7H₂O。综上所述，3株菌均可高效抑制疮痂链霉菌生长，环境适应性强，其中DXT2-4抗病促生效果最佳，具有较好的开发价值和应用前景，对促进马铃薯生产及环境安全可持续利用具有重要意义。

Abstract:

In recent years, potato scab caused by Streptomyces scabies is aggravating year by year, becoming an industrial problem urgently to be resolved. Screening antagonistic bacteria with good inhibitory effect and wide adaptability is the main measure to realize effective prevention and control of the disease. This study screened three strains of antagonistic bacteria DXT2-4, T2-1 and 21-14 with good inhibitory effect on S. scabies by using plate standoff test, and identified them as Bacillus altitudinis, Bacillus safensis and Bacillus pumilus, respectively, based on morphological characteristics, physiological and biochemical properties, and 16S rRNA gene sequences. DXT2-4, T2-1 and 21-14 showed the pot control efficacy of 68.83%, 48.57%, and 57.14%, respectively. The field control efficacy of the three strains was 59.48%, 34.58% and 51.75% in Hulun Buir, Inner Mongolia Autonomous Region and 55.14%, 36.05%, and 49.05% in Huizhou, Guangdong. The three strains could grow normally in the media with pH 1.0–13.0 and with 1%–11% NaCl, and they had inhibitory effects on Rhizoctonia solani, Verticillium dahliae, Alternaria solani, and Fusarium oxysporum. The indole-3-acetic acid yields of DXT2-4, T2-1, and 21-14 were 2.23, 1.11, and 1.67 mg/L, respectively. DXT2-4 and 21-14 demonstrated strong abilities to solubilize phosphorus. The optimal carbon source, nitrogen source, and inorganic salt for fermentation of strain DXT2-4 were 2% molasses+2% corn starch, 2% soybean meal, and 0.3% MgSO₄·7H₂O, respectively. These findings suggest the three strains of bacteria can efficiently inhibit the growth of S. scabies and have strong environmental adaptability. Particularly, DXT2-4 has the best effects of inhibiting the disease and promoting plant growth, showing a high development value and broad application prospects, this is of great significance for promoting sustainable potato production and ensuring the environmentally sound utilization of resources.