Nutritional Requirements for Axenic Growth of Some Haustorial Mycoparasites

Abstract

SUMMARY A study of the nutritional conditions required for axenic growth of five biotrophic haustorial mycoparasites, with emphasis on Tieghemiomyces parasiticus, was made on a basal casein hydrolysate medium. Four species failed to utilize glucose or other sugars and sugar utilization by the fifth one is doubtful. Glycerol was utilized readily by all species. Casein hydrolysate was not utilized as a carbon source. Four species were totally deficient for thiamine. T. parasiticus was favored by unusually high concentrations of thiamine and also was highly deficient for biotin. T. parasiticus and Dimargaris verticillata grew more rapidly on media with high concentrations of casein hydrolysate in the presence of glycerol but no growth of either parasite occurred on media with single amino acids. It appears that specific requirements for carbon sources, nitrogen sources, and vitamins may be common among the biotrophic mycoparasites. The nutritional requirements of the biotrophic (obligate) mycoparasites have remained a challenging problem. Extensive axenic growth of three biotrophic contact mycoparasites has been obtained following the addition of a growth factor, mycotrophein, obtained from a water extract from certain other fungi, to an appropriate basal medium containing glucose as the carbon source. These parasites are Calcarisporium parasiticum Barnett (Barnett and Lilly, 1958), Gonatobotrys simplex Corda (Whaley and Barnett, 1963), and Gonatorrhodiella highlei Smith (Gain and Barnett, 1970). However, few of the haustorial mycoparasites, which belong to the Mucorales and for the most part parasitize other Mucorales, are known to make more than a trace of axenic growth on the usual laboratory media. It is generally assumed that these media are incomplete for these parasites. Benjamin (1959, 1961) has made a morphological and taxonomic study of a number of the haustorial mycoparasites and has reported that 1 Published with the approval of the Director of the West Virginia University