Growth and respiration of psychrophilic species of the genus Typhula

Abstract

Growth of three snow mold fungi, Typhula idahoensis Remsb., T. incarnata Lasch ex Fr., and T. trifolii Rostr., was studied in agar and liquid culture. T. idahoensis was grown successfully in shake culture and its respiratory physiology investigated; some of the attendant problems are discussed.All three fungi were highly psychrophilic. The optimum temperatures for growth were 5–10 °C, the maximum about 20 °C and the minimum around −5 °C. Sclerotia were produced at all temperatures which permitted growth, but most abundantly at temperatures above 10 °C.Cultures grown at 10 °C ceased to grow on transfer to temperatures above 20 °C but, within limits, growth resumed on return to 10 °C after a lag period approximately proportional to the degree and duration of the temperature elevation.Oxygen uptake by T. idahoensis was optimal at 20 °C, about 15 °C higher than the optimum growth temperature.Respiratory quotients tended to be higher at 20 °C than at 5 °C and after starvation of the mycelium increased to a greater degree at 20 °C on addition of glucose or acetate. Starvation of the mycelium effectively reduced the level of endogenous reserves.The fungus was able to use, to differing degrees, a variety of hexose and pentose sugars as respiratory substrates. The percentage stimulation of the oxygen uptake by these sugars was greater at 20 °C than at 5 °C.