Specific effects of mutagens on Aspergillus niger producing citric acid

Starch digestion and adsorption by beta-amylase of Emericella nidulans (Aspergillus nidulans)

A mutant strain of Emericella nidulans MNU 82 was isolated by multistep mutation. The beta-amylase produced by the mutant was able to digest raw starch. It was readily and strongly adsorbed onto raw starch at pH 5.0. The enzyme to starch ratio was 1950 U/g starch. The enzyme showed no correlation between the capacity of raw starch digestion and adsorption of the enzyme.

Variability of Aspergillus niger after treatment with N-emthyl-N'-nitro-N-nitrosoguanidine

N-Methyl-N'-nitro-N-nitrosoguanidine influences strongly the variability of Aspergillus niger MU 90, particularly on long-term treatment. The number of spores capable of growth decreases with the duration of treatment and the number of morphological and biochemical mutants considerably increases. The highest number of mutants with increased organic acid production was obtained after a mutagenic treatment when the number of surviving spores decreased below 1%.