The Effect of Ammonia on Growth and Reproduction of Pilobolus Kleinii

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Abstract
SUMMARY The weight of mycelium and the numbers of trophocysts and zygospores produced by Pilobolus kleinii were greatly increased when certain concentrations of ammonium ion were added to a basal medium which contained asparagine, sodium acetate, hemin, thiamine, and salts. The stimulation did not appear to be due to changes in the pH of the medium. From the fact that casein hydrolysate, yeast extract, glucosamine, and cytidine monophosphate did not duplicate the effect of ammonium ion, it was concluded that ammonium ion was preferable to these substances as a source of nitrogen. The results of trials in which ammonium ion served as the sole source of nitrogen indicated that the pattern of stimulation was affected by the concentration of carbon source (acetate). The optimal concentrations of acetate (0.16 M) and ammonium ion (0.02 M) were the same for growth and asexual reproduction, but zygospore formation was favored by a more dilute medium (0.04 M acetate and 0.005 M ammonium ion).