Hyphal morphology modification in thermal adaptation by the white-rot fungus Fomes sp. EUM1

A thermotolerant white-rot fungus was identified as Fomes sp. EUM1. The strain exhibited maximum growth at 30 °C, with activation and inactivation energy values of 68 and 32 kJ/mol, respectively. The temperature affected the hyphal morphology, which was related to the thermotolerance of the microorganism: A shift from 30 to 40 °C in the growth temperature caused a decrease (15%) in mycelium branching; also longer (32%) and thinner (13%) hyphae were produced. In addition, as the temperature rose from 25 to 45 °C, an increase was observed in both the hyphal surface area (43%) and the surface growth rate (193%). The modification of the hyphal morphology suggests a strategy to colonize nutrient-rich areas while spending minimal energy for biomass formation under thermal stress.