甘蔗赤腐病内生拮抗菌YC89的筛选及鉴定

【目的】筛选防治甘蔗赤腐病(sugarcane red rot)的生防菌株。【方法】实验以前期分离获得的甘蔗内生细菌为目标菌,以甘蔗赤腐病的病原真菌镰孢炭疽菌(Colletotrichum falcatum Went.)为指示菌,采用平板对峙法筛选对该病菌有较强抑制作用的菌株,然后通过琼脂扩散法测定菌株代谢产物对抑菌活性的影响,并对具有较好拮抗效果的高效菌株进行抑菌广谱性分析并对其进行鉴定。最后通过形态学、生理生化特征以及16SrDNA和gyrA序列分析对高效菌株YC89进行鉴定。【结果】经初筛筛选到抑菌带均大于1.60 cm的5株拮抗细菌,其中X22、W2、YC89抑菌带均高达1.87 cm。对初筛得到的5株内生菌进行复筛,结果所示菌株YC89、H1、X22、W2、YT93对镰孢炭疽菌的抑菌率都在75%以上,其中菌株YC89对该病菌的抑菌效果最好,其抑菌率为78%。菌株YC89的发酵液、上清液、过滤液及粗蛋白提取液对镰孢炭疽菌的生长有较强的抑制作用,且菌株YC89对玉米大斑病、甘蔗梢腐病、草莓灰霉病等7种病原菌也有较好的抑制效果。通过菌株鉴定结果,初步将YC89菌株鉴定为贝莱斯芽孢杆菌(Bacillus velezensis)。【结论】菌株YC89对镰孢炭疽菌具有较好的抑制效果,表明其对甘蔗赤腐病的生物防治具有较大的应用潜力。

Screening and identification of endophytic antagonistic Bacteria YC89 in sugarcane red rot

Objective] Screening biocontrol strains for controlling sugarcane red rot caused by Colletotrichum falcatum Went. Methods] The endophytic bacteria isolated from sugarcane were used as target bacteria. The sugarcane red rot pathogenic fungus Colletotrichum falcatum Went. was used as an indicator. Strains with strong inhibitory effect on the pathogen were screened by confrontation culture. Antibacterial activity of the metabolites was determined by agar diffusion method. Then, the broad-spectrum analysis of the antimicrobial activity of highly effective strains with good antagonistic effect was carried out and identified. Finally, the high-efficiency strain YC89 was identified through morphological, physiological and biochemical characteristics in combination with 16S rDNA and gyrA sequence analysis. Results] Five strains of antagonistic bacteria with bacteriostatic bands greater than 1.60 cm were screened by initial screening, among which X22, W2 and YC89 were up to 1.87 cm. The five endophytic bacteria obtained from the initial screening were rescreened. Strains YC89, H1, X22, W2 and YT93 had a inhibition rate above 75% against sugarcane red rot, among which YC89 had the best inhibition rate of 78%. The culture solution, supernatant, filtrate and crude protein extract of strain YC89 showed strong antagonistic activities to the hyphal growth of Colletotrichum falcatum Went. In addition, strain YC89 also had good activity against 7 plant pathogenic fungi. Strain YC89 was identified as Bacillus velezensis. Conclusion] Strain YC89 has good biocontrol effect on sugarcane red rot pathogen, and has great application potential in the biological control of sugarcane red rot.