Role of pyruvate and ascorbate production in regulation of antioxidant enzymes and membrane LPO levels in Fusarium acuminatum

The role of pyruvate and ascorbate in the regulation of superoxide dismutase (SOD); catalase (CAT); glutathione peroxidase enzymes; and, therefore, membrane lipid peroxidation (LPO) levels in Fusarium acuminatum was investigated in media containing either glycerin or glucose as a carbon source, depending on the incubation period, in the range of 5-25 g/L. Increasing SOD activity between d 9 and 16 of the incubation period showed a positive correlation with a significant increase in pyruvate production up to 15 g/L of glycerin and glucose. In addition, maximum ascorbate production was observed at 15 g/L of glycerin as 82.5 +/- 2.1 and 20 g/L of glucose as 54 +/- 1.51, whereas CAT activity decreased with an increased concentration of both carbon sources. When compared with the LPO levels determined in media supplemented with glycerin and glucose, the minimum LPO level was 1.88 +/- 0.028 nmol of malondialdehyde/g wet wt at 15 g/L of glycerin on d 16, at which it was also observed to have a maximum pyruvate and ascorbate production and SOD, CAT, and GSH-Px activities of 75 +/- 1.42 mug/mL, 82.5 +/- 2.1 mug/mL, 32.5 +/- 0.634 mug/mL, 86.8 +/- 2.58 IU/mg, and 1.867 IU/mg, respectively. These results indicate that the biosynthesis of pyruvate and ascorbate may be involved in the regulation of antioxidant enzymes, depending on the glycerin and glucose concentrations, and also this defense network was effective in preventing membrane damage from oxidative stress.