Chiang Mai Journal of Science

 Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici (Fox), is a serious disease affecting tomato cultivation worldwide. Recently, biological control using antagonistic microorganisms has widely been claimed as a sustainable way of controlling Fusarium wilt in crops. In order to discover an efficient Bacillus stain for biocontrol of Fusarium wilt disease and for improvment of tomato growth, 3 Bacillus strains designated as BMG4, KMS17 and PGA106, were demonstated for tomato plant growth promotion (PGP) and biocontrol activity against Fusarium wilt disease in pot condition for 102 days plantation. Among them, strain PGA106 showed the highest significantly increased tomato plant growth, yielding 22.9% increased shoot fresh weight, 53.9% increased shoot dry weight and 46.15% increased fruit yield compared to the control. In Fox infested condition, PGA106 treatment significantly lead to 66.7% reduction of wilt incidence while causing 21.2% increased shoot fresh weight, 42.8% incresed shoot dry weight and 194.6% increasd fruit yield as compared to the Fox infested control. Strain PGA106, identified as Bacillus velezensis by the analysis of 16S rDNA sequences, showed several growth promoting traits as the ability on mineral phosphate solubilization and the production of IAA, siderophores, PGP volatiles, biofilm and γ-PGA. In addition, the properties that actively contribute antagonistic interaction with FOX by PGA106 were confirmed by synthesis of several fungal cell wall hydrolytic enzymes and lipopeptides that inhibited the germination and degradation of Fox conidia. Lipopeptide synthesis was indicated by the existence of lipopeptide genes on the genome. A talc-based bioformulation of PG106 was prepared to make it convenient to be use and extent storage time. Storage viability of the bioformulation at temperature between 4-55°C found that the specific rate of degradation increased linearly with the temperature up to 35°C which followed the Arrhenius equation.