Final answer:
Fungi grow best at slightly acidic pH values of 5.0-6.0. Most fungi are acidophiles and thrive in acidic environments.
Step-by-step explanation:
Fungi grow best at slightly acidic pH values of 5.0-6.0. This is because most fungi are considered acidophiles, which means they thrive in acidic environments. For example, the sulfur-oxidizing Sulfolobus spp. and species of the archaean genus Ferroplasma are extreme acidophiles that can survive at pH values as low as 2.5-3.5 and 0-2.9, respectively. Acidophilic microorganisms have adaptations to survive in strong acidic environments, such as increased negative surface charge in proteins and active ejection of H+ ions out of cells.