[Identification of spore germination and virulence related biomarkers from Beauveria bassiana using an LC-MS-based metabolomic technique].

Objective: To identify biomarkers associated with germination and virulence of Beauveria bassiana.

Methods: Spore germination rate and virulence of seven B. bassiana isolates against Euproctis pseudoconspersa were determined, and an LC-MS-based metabolomic analysis was applied to identify the biomarkers from mycelia and conidial extracts associated with spore germination and virulence.

Results: The metabolites of carnitine, hercynine, acetylcarnitine, alpha, alpha-trehalose; Octa-Me, arg-arg-gln, phosphatidylethanolamine (PE(18:2/0:0)), phosphotidylcholine (PC(18:3/0:0)) and PC(18:2/0:0)) were higher in the mycelia of highly virulent isolates than those less virulent strains. Conidia of isolates with a high germination rate were characterized by containing higher levels of 2, 3-dimethylmaleate, acetylcarnitine, propionyl-carnitine and PC(18:2/0:0). Histamine, 2,5-pyrrolidinedicarboxylic acid; Diamide, carnitine, acetylcarnitine, propionyl-carnitine, butyrylcarnitine, PE(18:2/0:0), PC(16:1/0:0) and PC(18: 3/0:0) were higher in the conidia of highly virulent isolates. Furthermore, relative content comparison of insecticidal cyclopeptides, such as beauverolides, beauvericins and bassianolide in mycelia showed that the content of a single peptide was not highly related to fungal virulence. However, the contents of 9 peptides were found higher in the highly virulent isolate Bb1898, suggesting that they might exert synergetic effects against insect hosts.

Conclusion: The common biomarkers related to fungal virulence and germination are acyl carnitine and phospholipid which may play roles in maintaining appressorium turgor pressure and providing energy for penetrating the host cuticle.