Walaszczyk Ewa, Podgórski Waldemar, Janczar-Smuga Małgorzata, Dymarska Ewelina
1Department of Biotechnology and Food Analysis, Institute of Chemistry and Food Technology, Faculty of Engineering and Economics, Wroclaw University of Economics, Komandorska 118-120, 53-345 Wrocław, Poland.
2Department of Animal Food Technology, Institute of Chemistry and Food Technology, Faculty of Engineering and Economics, Wroclaw University of Economics, Komandorska 118-120, 53-345 Wrocław, Poland.
Chem Zvesti. 2018;72(5):1089-1093. doi: 10.1007/s11696-017-0354-x. Epub 2017 Dec 5.
The pH of the medium is the key environmental parameter of chemical selectivity of oxalic acid biosynthesis by . The activity of the enzyme oxaloacetate hydrolase, which is responsible for decomposition of oxaloacetate to oxalate and acetate inside the cell of the fungus, is highest at pH 6. In the present study, the influence of pH in the range of 3-7 on oxalic acid secretion by W78C from sucrose was investigated. The highest oxalic acid concentration, 64.3 g dm, was reached in the medium with pH 6. The chemical selectivity of the process was 58.6% because of the presence of citric and gluconic acids in the cultivation broth in the amount of 15.3 and 30.2 g dm, respectively. Both an increase and a decrease of medium pH caused a decrease of oxalic acid concentration. The obtained results confirm that pH 6 of the carbohydrate medium is appropriate for oxalic acid synthesis by , but the chemical selectivity of the process described in this paper was high in comparison to values reported previously in the literature.
培养基的pH值是草酸生物合成化学选择性的关键环境参数。负责在真菌细胞内将草酰乙酸分解为草酸盐和乙酸盐的草酰乙酸水解酶的活性在pH 6时最高。在本研究中，研究了pH值在3至7范围内对W78C从蔗糖中分泌草酸的影响。在pH 6的培养基中达到了最高草酸浓度，为64.3 g/dm。由于培养肉汤中分别存在15.3 g/dm和30.2 g/dm的柠檬酸和葡萄糖酸，该过程的化学选择性为58.6%。培养基pH值的升高和降低都会导致草酸浓度降低。所得结果证实，碳水化合物培养基的pH 6适合于W78C合成草酸，但与先前文献报道的值相比，本文所述过程的化学选择性较高。
