Effect of biotic and abiotic factors on conidial germination of a saprobic ammonia fungus Amblyosporium botrytis

The effects of NH(4)Cl concentration (0.1–1600 mM), temperature (5.0–35.0°C), pH (3.0–11.0), conidial density (2.5 × 10(5)–1.0 × 10(7) conidia/ml), and conidial maturation (0–21 days) on the conidial germination of the early phase (EP) ammonia fungus Amblyosporium botrytis were investigated. The optimum NH(4)Cl concentration for conidial germination was 300 mM. No germination was observed above 1000 mM NH(4)Cl, while low NH(4)Cl concentration (0.1–30 mM) retarded the conidial germination. The conidia did not germinate in distilled water. The effective pH ranges for the conidial germination were from 5.0 to 9.0 with optimum at 8.0. Germination was possible from 5.0°C to 35°C with the optimum at 15°C. These results demonstrate that ammonium-nitrogen concentration and pH are principal factors in the conidial germination of A. botrytis. It is expected that the obtained physiological characteristics of A. botrytis are suitable to colonize in nitrogen-enriched soil as the EP ammonia fungus.