Metabolic response and volatile profile induced by temperature, on Colletotrichum fragariae and Rhizopus stolonifer

During growth, fungi usually synthesize and emit different metabolic products. The objective of this work was to determine the metabolic activity of Colletotrichum fragariae and Rhizopus stolonifer isolated from strawberries, based on their biomass production, the synthesis of ergosterol and their respiration rate, and to identify their volatile profile, during an incubation period of up to 30 days at 10 and 20°C. For C. fragariae and R. stolonifer, the biomass production at the end of incubation was 30% and 25% higher at 10°C than at 20°C, respectively, and ergosterol production was higher at 10°C than at 20°C. Regardless of the incubation temperature, the typical respiration rate pattern was shown. Terpenes were the major chemical group identified in both fungi, accounting for 41% and 84% of the volatile composition of C. fragariae at 10 and 20°C, respectively, while in the case of R. stolonifer, they represented 59% and 45% at 10 and 20°C, respectively; α-terpineol was detected during the growing period of C. fragariae and R. stolonifer at 10 and 20°C, whereas γ-terpinene was emitted only by R. stolonifer at 20°C. Therefore, they might serve as specific indicators of the presence of these two fungi.