“…The higher gluconic acid production found at optimal temperatures can be explained by an enhanced enzyme activity and enzyme secretion into the medium, because higher biomass concentrations were obtained at lower temperatures. When comparing the presented results (29-318C), slightly lower optimum temperatures, between 28 and 308C, have been reported for the discontinuous gluconic acid fermentation in A. niger and Penicillium janthinellum (Bernhauer, 1926;Chopra et al, 1975;Mandal and Chatterjee, 1986;Rehm, 1980). On the other hand, Herrick and May (1928) reported about an optimum temperature of 258C for P. luteum-purpurogenum and Ambekar et al (1965) of about an optimal temperature of 248C for P. chrysogenum HA-10.…”