The mechanism of the formation of organic acids by mould fungi. 5. The influence of arsenite on Aspergillus niger

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Abstract
Spores of A. niger is a glucose medium developed normally in presence of Na arsenite at concns. of 0.001 to 0.004 M, but germination was inhibited at 0.01 [image]. Preformed mycelial felts of A. niger treated with arsenite at 0.001, 0.002, and 0.004 [image], respectively, subsequently consumed more sugar, accumulated more felt material and produced a greater total of acids (citric, oxalic and gluconic) in a given time than did controls in absence of arsenite. Enhancement of metabolic activity was greatest at 0.004 [image]. In presence of 0.01 [image] arsenite, sugar consumption by preformed felts was not stimulated, while increase in felt wt. was less than in the arsenite-free control. Arsenite at 0.020 [image] almost completely suppressed the mold''s activities. Arsenite at all concns. between 0.001 and 0.010 [image] reduced CO2 output. This effect was greatest at 0.004 [image]. The bearing of these results on the mode of formation of citric acid is discussed.