Regulation of ammonia uptake in aspergillus nidulans.

The ammonia uptake in A. nidulans was found to be linear for about 20 min, and was proportional up to 1.5 mg/ml dry cell density. The transport of ammonia does not involve energy. Normal and biotin deficient A. nidulans showed an identical Km-values of 10.26 X 10(-5) M ammonia for uptake. The uptake of ammonium ion has been shown to be regulated by the intracellular concentration of ammonia.