Screening of Antagonistic Bacteria Having Antifungal Activity against Brown Spot and Sheath Rot of Rice

Myeong Seon Ryu1   Hee-Jong Yang1   Su-Ji Jeong1   Ji-Won Seo1   Do-Youn Jeong1,*   

1Microbial Institute for Fermentation Industry (MIFI), 61-27, Minsongmaeul-gil, Sunchang-eup, Sunchanggun, Jeollabuk-do 56048, Korea

Abstract

Brown spot and sheath rot of rice are caused by fungal pathogens such as Curvularia lunata, Cochliobolus miyabeanus, and Sarocladium oryzae, and cause losses such as reduced rice yield and quality, which is an enormous problem with serious long-term effects. To search biological control agents of phytopathogenic fungi, five kinds of useful Bacillus-like isolates which are excellent in extracellular enzyme activity and produce siderophore were selected from paddy soil of Sunchang in Korea. The selected isolates were tested for excellent antifungal activity against three of the phytopathogenic fungi that frequently occur in rice, and JSRB 177 strain had the most excellent antifungal activity. Based on the experimental results, JSRB 177 is finally selected as a candidate for biological control and identified to Bacillus subtilis through 16S rRNA sequence analysis. In addition, physiological characteristics of JSRB 177 confirmed by analysis of carbohydrate fermentation patterns and enzyme production ability. Based on the above results, JSRB 177 is expected to be used as a biological control agent for the rice pathogenic fungi. In the future, further studies related to industrialization such as port test and establishment of mass production process are needed.

Figures & Tables

Fig. 1. Phylogenetic tree based on nearly complete 16S rRNA gene sequences of strain JSRB 177 and type strains. JSRB 177 showed the phylogenetic position similar to type strains. GenBank accession numbers are given in parentheses. Branching pattern was generated by maximum likelihood method. Bar, 0.005 substitutions per nucleotide position. Bootstrap values are expressed as percentages of 1,000 replicates.