Abstract:

Bacillus tequilensis DZY6715 is a biocontrol strain that has a good inhibitory effect on Colletotrichum fructicola in Camellia oleifera. In order to clarify the different metabolic substances and their regulatory functions of the strain at the early and late stages of growth, based on the growth curve of strain DZY6715, plate confrontation method was used to determine the inhibitory activity of the strain against C. fructicola in the early and late stages of growth, and then non-targeted metabolomic technology was employed to perform bioinformatics analysis of the fermentation broth in these two stages. The results showed that antifungal activity of strain DZY6715 in the early growth stage was significantly weaker than that in the late growth stage. In the sample DZYB72h_vs_DZYB24h, 32 pathways were annotated, and 183 differential metabolites were enriched in the top 20 pathways. Among them, there were 5 pathways with high potential importance, and 84 differential metabolites of 27 kinds were enriched. The involved differential metabolites were mainly amino acids and organic acids, accompanied by norfloxacin, N-acetyl-d-glucosamine, adenosine, phenol, etc. Furthermore, the total expression of amino acids in the early growth stage was significantly higher than that in the late growth stage, while the total expressions of organic acids and other differential metabolites in the late growth stage were significantly higher than that in the early growth stage. Therefore, this study confirmed that amino acids are mainly involved in the construction of cell structure and have antibacterial function, while organic acids, norfloxacin, adenosine and other substances are more important regulators in the process of resistance to stress.

Key words: Bacillus tequilensis, early growth stage, late growth stage, differential metabolites, non-targeted metabolomics