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从甘肃省景泰县条山农场不同连作年限的马铃薯地块中取根际土样品,分离筛选马铃薯黑痣病病原菌-立枯丝核菌(Rhizoctonia solani)的拮抗菌。采用土壤平板稀释、对峙法筛选拮抗菌;结合形态特征、生理生化及16Sr DNA分子鉴定;采用单因素试验设计对G1菌株的生长条件进行初步试验。通过初筛和复筛,从108株细菌中获得1株对立枯丝核菌拮抗效果稳定、拮抗能力较强的细菌G1。采用平板对峙法测定其拮抗作用,抑菌带宽度达6mm,抑菌圈直径>2.5 cm,抑菌率为66.7%。结合形态特征、生理生化及16Sr DNA分子鉴定,G1为类芽孢杆菌(Paenibacillus sp.);采用单因素试验设计对G1菌株的生长条件进行初步试验。结果表明,菌株G1在4℃~45℃,p H 5~10,盐浓度0~50 g·L-1都能生长,碳源、氮源利用广泛,最适条件为:温度37℃,p H 7,蔗糖为碳源,蛋白胨为氮源,盐浓度为10 g·L-1。拮抗菌G1被鉴定为类芽孢杆菌,该菌株抑菌带较宽、抑菌效果稳定,生长条件与马铃薯生长的大田环境基本相符,具有作为一株优良生防菌的必要条件。
Rhizoctonia solani was isolated and screened for Rhizoctonia solani, a rhizosphere soil sample from potato plots of different continuous cropping years in Jianshan Farm, Jingtai County, Gansu Province. Antagonistic bacteria were screened by soil plate dilution and confrontation method. Morphological characteristics, physiological, biochemical and molecular identification of 16S rDNA were carried out. The growth of G1 strain was tested by single factor experiment. Through screening and re-screening, a strain of Bacterium Rhizoctonia solani that has stable antagonistic activity and strong antagonistic ability was obtained from 108 strains of bacteria. Antagonistic effect was measured by plate confrontation method. The antibacterial band width was 6mm, the diameter of inhibition zone was> 2.5 cm and the antibacterial rate was 66.7%. According to morphological, physiological and biochemical characteristics and 16Sr DNA molecular identification, G1 is Paenibacillus sp. The single factor experimental design was used to test the growth of G1 strain. The results showed that strain G1 could grow from 4 ℃ to 45 ℃ with p H 5 ~ 10 and salt concentration from 0 to 50 g · L -1. The optimum conditions were as follows: temperature 37 ℃, p H 7, sucrose as carbon source, peptone as nitrogen source, and salt concentration of 10 g · L -1. Antagonistic bacteria G1 was identified as Paenibacillus. The bacteriostasis bacterium belonged to a wide bacteriostasis zone with stable bacteriostasis. The growth conditions were consistent with the field environment of potato growth, which was the necessary condition for an excellent biocontrol agent.