Identification of an Antagonistic Bacterium Against Ralstonia solanacearun and Primary Study of Effect on Disease Resistance

Abstract:

On the basis of morphological, physiological and biochemical characters as well as sequence analysis of 16S rDNA, the antagonistic bacterium strain 3-1-16 was identified. Under optics microscope, the strain was bacilliform, G⁺, stained evenly purple. Furthermore, many granulose structures were found in cell without parasporal crystal under EM observation. According to Biolog Bacteria Identified system, 3-1-16 strain has 98% similarity with Bacillus megaterium MO31. A 1443-bp 16S rRNA gene sequence was obtained from strain 3-1-16. The BLAST search of the GenBank database using this sequence showed its similarity to many species of Bacillus. It was 99.4% similar to the 16S rRNA gene sequence of Bacillus megaterium strain MO31 (GenBank accession No. AY553118.1) over 1437 bases. Phylogenetic tree of Bacillus 16S rRNA gene sequences showed that 3-1-16 strain was clusterred with three Bacillus megaterium. Based on those characteristics, strain 3-1-16 was identified as Bacillus megaterium GIMA 1.001. Glasshouse trials demonstrated that the control efficiency of 3-1-16 strain against tomato bacterial wilt disease was 81.3%