ROLE OF NITROGEN IN FUNGOUS THERMOGENESIS

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Abstract
The influence of additions of asparagine, NH4Cl, monoammonium phosphate, (NH4)2SO4 and Ca(NO3)2 on thermogenesis and loss in dry weight of corn-cob meal cultures of Aspergillus flavus, A. terreus, Peni-cillium oxalicum and Rhizopus tritici is reported. The 5 forms of N each stimulated both thermogenesis and loss in dry weight when added to cultures of the first 3 fungi. With Rhizopus tritici, all forms of N except the nitrate markedly increased thermogenesis, but only asparagine increased the dry-weight loss. Asparagine was found to be most generally suitable for the 4 fungi employed. The highest temp. recorded[long dash]49.25[degree]C[long dash]was reached in cultures of A. flavus and A. terreus when supplied with asparagine. This temp. was 21.5[degree]C above cultures containing no added N. The greatest loss in dry weight, in 28 days, in the expts. reported, was 16.95% in cultures of A. terreus supplied with asparagine. N additions ranging from 0.01 to 0.10 g. per 100 g. of dry cob-meal generally resulted in progressive increases in thermogenesis in cultures of A. flavus. The average maximum rise in temp. above the controls for additions of asparagine, monoammonium phosphate and Ca(NO3)2[long dash]at the rate of 0.00. 0.01, 0.05, 0.10 g. per 100 g. of meal[long dash]were 6.67[degree], 7.67[degree], 15.25[degree] and 20.25[degree]C respectively. Additions greater than 0.10 g. up to 3.2 g. did not appreciably increase thermogenesis. Use of 3.2 g. N, as monoammonium phosphate and Ca(NO3)2, resulted in an average maximum rise of only 11.38[degree]C. Progressive increases in dry-weight loss in cultures of A. flavus followed the larger additions of asparagine, monoammonium phosphate and Ca(NO3)2, respectively, up to 1.2 and 1.6 g. per 100 g. of dry meal.