马铃薯黑痣病生防菌的筛选和鉴定及其生长条件的研究

Isolation and identification of antagonistic strains against black scurf of potato and conditions for their growth

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16SrDNA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16SrDNA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℃,pH5～10,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℃,pH 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。

Bacteria with antagonistic activity against potato black scurf pathogen （ Rhizoctonia solani） were isolated from the rhizosphere soils with different years of continuous cropping in hill farm of Jingtai county, Gansu Province. An- tagonistic bacteria were isolated from soil through dilution plates and antagonistic plates. Based on the morphological characteristics, physiological and biochemical tests, and 16SrDNA sequencing analysis were performed. Single factor ex- periment design was carried out to discuss the growth conditions of strain G1. One of the isolated strains, G1, which showed the strongest antagonism, was selected from 108 bacterial strains. It produced an inhibition zone with 6.0mm width and 〉 2.5cm diameter, and an inhibitory rate at 66.7% through confronting incubation. According to the mor- phological characteristics, physiological and biochemical tests, and 16SrDNA sequence analyses, it was preliminarily i- dentified to be Paenibacillus sp. In addition, a single factor experiment design was carried out to examine the optimal growth conditions for G1. The results showed that the bacteria could grow at 4℃ - 45℃ with pH 5 ~ 10 and salt concentration 0 to 50 g·L^-1. The optimal conditions for G1 growth was found to be 37℃ inoculation with pH at 7 using sucrose and peptone as carbon and nitrogen sources respectively, the newly selected PaenibaciUus sp. G1 showed broad pathogen （ Rhizoctonia solani ）. The growth condition for teria as a good biocontrol strain. as well as with a salt concentration at 10 g·L^-1. In conclusion, inhibition zone, with a stable effect against potato biack scurf G1 was similar to those for potato growth, owning necessary eriteria as a good biocontrol strain.