A mutant Corynebacterium sp. requiring threonine and cultivated for 3 d in a medium containing 15% sucrose, 8% corn-steep and 50 micrograms biotin per litre accumulated 14.5 g L-homoserine per litre. The possibility of fermenting the homoserine obtained for threonine and lysine production was investigated.

Production of L-lysine was followed in two lysine-accumulating mutants of Corynebacterium glutamicum ATCC 13287 in media containing sucrose, ethanol, acetic acid or a mixture of acetic acid and ammonium or sodium acetate. It was found that acetate is the best substitution for sucrose.

Several tens of mutants were obtained by UV irradiation of a spore suspension of Aspergillus niger. Producers yielding large amounts of citric acid were selected on a modified Czapek agar containing methyl red as pH indicator. After a submerged cultivation in flasks with baffles, a mutant characterized by yellow pigmentation on wort agar and by yields of citric acid up to 74.6% in the medium containing glucose was chosen from 130 isolates tested.

No abstract

Production strains Glucmobacter ozydans used in manufacture of L-sorbose from commercial D-glucitol were evaluated by HPLC determination of D-glucitol, L-sorbose, D-fructose, D-mannnitol, D-arabinitol, D-xylulose, and D-threo-2,5-hexodiulose in the course of fermentation. Serious differences were observed among the strains apparently identical by standard methods.