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

Abstract:

[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.