Effect of Amino Acids on Fusarium oxysporum Growth and Pathogenicity Regulated by TORC1-Tap42 Gene and Related Interaction Protein Analysis

Free amino acids (AAs) formed in fermented meat products are important nitrogen sources for the survival and metabolism of contaminating fungi. These AAs are mainly regulated by the TORC1-Tap42 signaling pathway. Fusarium spp., a common contaminant of fermented products, is a potential threat to food safety. Therefore, there is an urgent need to clarify the effect of different AAs on Fusarium spp. growth and metabolism. This study investigated the effect of 18 AAs on Fusarium oxysporum (Fo17) growth, sporulation, T-2 toxin (T-2) synthesis and Tri5 expression through Tap42 gene regulation. Co-immunoprecipitation and Q Exactive LC-MS/MS methods were used to detect the interacting protein of Tap42 during specific AA treatment. Tap42 positively regulated L-His, L-Ile and L-Tyr absorption for Fo17 colony growth. Acidic (L-Asp, L-Glu) and sulfur-containing (L-Cys, L-Met) AAs significantly inhibited the Fo17 growth which was not regulated by Tap42. The L-Ile and L-Pro addition significantly activated the sporulation of ?FoTap42. L-His and L-Ser inhibited the sporulation of ?FoTap42. In T-2 synthesis, ?FoTap42 was increased in GYM medium, but was markedly inhibited in L-Asp and L-Glu addition groups. Dose-response experiments showed that 10-70 mg/mL of neutral AA (L-Thr) and alkaline AA (L-His) significantly increased the T-2 production and Tri5 expression of Fo17, but Tri5 expression was not activated in ?FoTap42. Inhibition of T-2 synthesis and Tri5 expression were observed in Fo17 following the addition of 30-70 mg/mL L-Asp. KEGG enrichment pathway analysis demonstrated that interacting proteins of Tap42 were from glycerophospholipid metabolism, pentose phosphate pathway, glyoxylate and dicarboxylate metabolism, glycolysis and gluconeogenesis, and were related to the MAPK and Hippo signaling pathways. This study enhanced our understanding of AA regulation in fermented foods and its effect on Fusarium growth and metabolism, and provided insight into potential ways to control fungal contamination in high-protein fermented foods.

Automated summary

Free amino acids formed in fermented meat products are crucial for the survival and metabolism of contaminating fungi, and their regulation is mainly controlled by the TORC1-Tap42 signaling pathway. This study investigated the effect of 18 amino acids on the growth, sporulation, toxin synthesis, and gene expression of Fusarium oxysporum. The results showed that certain amino acids positively regulated Fo17 growth and sporulation, while others significantly inhibited growth, not regulated by Tap42. This study contributes to our understanding of amino acid regulation in fermented foods and provides insights into controlling fungal contamination.