Growth and sporulation of Mucor pusillus

Abstract

The nitrogen nutrition of the thermophilic fungus Mucor pusillus Lindt. was studied at 50° C (5° above the optimal growth temperature). The fungus utilized inorganic nitrogen in the form of NH 4 + , NO 3 - , and NO 2 - , and also a wide range of organic sources of nitrogen. Nitrate was the best inorganic nitrogen source tested. Of 29 amino acids presented as single nitrogen sources the fungus grew on all but p -aminobenzoic acid (PABA), hydroxyproline, creatine and thyroxine. Glycine, alanine, proline, aspartic acid and glutamic acid were the most efficient single amino acids for growth, and cysteine, cystine, DOPA, tryptophan and histidine the least efficient. Casein, peptone, glycyl glycine and urea also supported good growth. Buffering the culture medium by the addition of sodium succinate reduced the amount of growth of M. pusillus except with ammonia, cystine, methionine or histidine when buffering increased growth. M. pusillus sporulated well on a wide range of inorganic and organic nitrogen sources, being most profuse on ammonia, glutamic acid, tyrosine, serine, the sulphur-containing and basic amino acids, casein, gelatin, peptone and urea. Buffering tended to reducc sporulation.