Production of Calcium Gluconate by Penicillium chrysogenum

AMBEKAR, G. R. (Hindustan Antibiotics Ltd., Pimpri, India), S. B. THADANI, AND V. M. DOCTOR_ Production of calcium gluconate by Penicillium chrysogenum in submerged culture. Appl. Microbiol. 13:713-719. 1965.-The waste mycelium of Penicillium chrysogenum HA-10 (obtained at the end of penicillin fermentation), or a 24hr-old freshly grown vegetative inoculum of this organism, was found to utilize glucose for the production of calcium gluconate by submerged fermentation in shake flasks. After 72 to 96 hr of fermentation at 24 C, 90 to 95% of the reducing sugar from the 15%o glucose medium was converted to calcium gluconate. Reuse of the mycelium for successive experiments reduced the fermentation period to 72 hr or less because of an enhancement of glucose utilization. Ten successive batches of 15% glucose medium were fermented by the reuse method. Fermentation media containing up to 30% glucose could be used, provided boric acid was added to prevent the precipitation of calcium gluconate formed. We found that 30% hydrol (a by-product of glucose manufacture containing 50 to 55% reducing sugar), when used in place of glucose in the fermentation medium, inhibited the rate of glucose utilization. However, this effect was partially reversed by pretreatment of hydrol with 2 to 4% activated charcoal before addition to the fermentation medium. Shortly after Molliard (1922) reported the synthesis of gluconic acid by a fungus, Butkewitsch (1923) found a strain of Aspergillus niger which, in the presence of calcium carbonate, formed gluconic acid almost to the exclusion of other acids. A few years later, May et al. (1927) initiated the work of a U.S. Department of Agriculture group, and tested fungi, especially those belonging to the genera Aspergillus, Mucor, Penicillium, and Monilia. They first reported the production of gluconic acid by P. luteum purpurogenum group. After studying (Herrick and May, 1928) the conditions for the production of gluconic acid by this organism in surface culture, with the use of shallow pans, Moyer, May, and Herrick (1936) reported that this strain of Penicillium lacked biochemical and vegetative vigor and investigated a large number of Penicillium species, which led to the discovery of a culture of P. chrysogenum (5034-11) having a greater ability to synthesize gluconic acid, than other Penicillium strains. Using this culture of P. chrysogenum (5034-11) and carrying out fermentations at 30 C in shallow aluminum pans with a surface-volume ratio of 0.4 to 0.5, these workers obtained a 60% conversion of glucose to gluconic acid at the end of 8 to 10 days. They also investigated the production of gluconic acid by P. chrysogenum when cultivated in submerged culture, and reported yields of 80 to 87% (based on the quantity of glucose supplied) in 8 days. The purpose of the present study was (i) to investigate the use of P. chrysogenum (HA-10) mycelium (obtained at the end of penicillin fermentation) in the calcium gluconate fermentation, (ii) to determine the fermentation conditions for this organism which will produce high yields of calcium gluconate under submerged conditions, and (iii) to investigate the use of hydrol (a byproduct of glucose manufacture containing 50 to 55% reducing sugar) as the starting raw material in place of glucose for calcium gluconate fermentation. A preliminary report on this study has appeared (Doctor and Ambekar, 1964). MATERIALS AND METHODS Cultures. P. chrysogenum strain Thom HA-10, strain HA-9 (a mutant of a Russian strain), and strain Q 176 were used in these investigations. The strains were maintained on agar slants of the following composition: 1% glycerol, 1% glucose, 1% NaCl, 0.5% yeast extract, 0.005% MgSO47H20, 0.01% KH2PO4, and 2% agar. Spore inoculum. Spores of P. chrysogenum were obtained by the following procedure (Thirumalachar and Gopalkrishnan 1963). A 100-g 713 on O cber 3, 2017 by gest ht://aem .sm .rg/ D ow nladed fom AMBEKAR, THADANI, AND DOCTOR