The aim of the work was to examine the influence of glucose concentration as a sole carbon source on oxalic acid synthesis by Aspergillus niger in submerged fer- mentation. Cultivations were conducted in synthetic medium containing glucose di- luted to 100, 125, 150 and 175 g·dm^-3. The highest product concentration 64,2 g·dm^-3 was obtained in medium containing 150 g·dm^-3 of glucose. There were also 15,4 g·dm^-3 of citric acid and 28,7 g·dm^-3 of gluconic acid present. Chemical selectivity of the process was 59,2%. The highest productivity and the highest substrate yield equalled respective- ly 2,9 g·dm^-3·d^-1 and 61,6% was obtained in medium containing 100 g·dm^-3 of substrate. In conclusion, optimal glucose concentration in medium was recognised as 150 g•dm-3 be- cause of the highest product concentration.

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