Study on the technologies of enhanced heat resistance in the spores of Bacillus amyloliquefaciens PHODG36

The heat resistance of the spore directly affects the production efficiency and cost of the dry powder of technical concentrate for Bacillus biocontrol bacteria. In order to develop the techniques to enhance the spore heat resistance of B. amyloliquefaciens PHODG36, a mutant strain BBW-11 of B. amyloliquefaciens PHODG36 with enhanced spore heat resistance was obtained by heat-treated mutagenesis and variable temperature mutagenesis. The spore survival rate of BBW-11 increased by more than 55.0%, while no significant difference in terms of colony morphology, biofilm formation, growth dynamics and antifungal activity compared to the wild-type strain PHODG36. The appropriate protective agent and treating conditions of BBW-11 were determined by orthogonal tests, and the technology to enhance the spore heat resistance of strain PHODG36 was established such as ‘the heat resistant mutant strain BBW-11 + 0.5% sucrose + 55 ℃ temperature treating for 0.5 h’, the spore survival rate was 2.3 times higher than that of the untreated mutant strain BBW-11 and 2.8 times higher than that of the wild-type strain PHODG36. In conclusion, the technique to enhance the spore heat resistance of strain PHODG36 was established in this study, which provides a technical support for the optimization of the spray drying process of the dry powder.