Axenic Growth and Nutrition of Gonatobotryum Fuscum

Abstract
SUMMARY Gonatobotryum fuscum, a contact biotrophic mycoparasite, has been cultured axenically for the first time, the best medium being a glucose-yeast extract medium (10–2 g/liter) supplemented with thiamine (4–8 mg/liter), biotin (0.2-0.4 mg/liter), and mycotrophein, a water soluble compound extracted from the host and some nonhost fungi. This parasite is the fourth species of its type to be studied and is similar to the other three (Calcarisporium parasiticum, Gonatobotrys simplex, and Gonatorhodiella highlei) in that they are deficient for the same growth factor, mycotrophein. The optimum concentrations of thiamine and biotin were unusually high and may reflect the difficulty with which these vitamins enter the cells. The addition of dimethyl sulfoxide (DMSO) increased growth rate, total growth and glucose utilization. Of the 13 carbon sources tested, G. fuscum made much greater growth on D-glucose than on any other carbon source. D-fructose, D-mannose, and D-galactose were also utilized. Yeast extract was the best source of nitrogen, but L-glutamic acid and L-aspartic acid were utilized well.