Important Role of Catalase in the Production of β-carotene by Recombinant Saccharomyces cerevisiae under H2O2 Stress

The effect of H2O2 supplement on cell growth and beta-carotene productions in recombinant Saccharomyces cerevisiae CFW-01 and CFW-01 ctt1 deficiency in cytosolic catalase were investigated in shaking flasks. The results showed that supplement of H2O2 (0.5 and 1.0 mM) can significantly stimulate the beta-carotene production. However, beta-carotene levels of CFW-01 ctt1 Delta under 0.5 and 1 mM H2O2 were 16.7 and 36.7% lower than those of CFW-01, respectively. Although lacking cytosolic catalase, no significant differences in cell growth were observed between CFW-01 ctt1 Delta and CFW-01 under the same level of H2O2 stress. These results suggest that beta-carotene can act as an antioxidant to protect the recombinant yeast from H2O2 oxidative damage in the absence of cytosolic catalase. However, catalase still plays an important role in the production of beta-carotene under H2O2 stress. If catalase can not timely decompose H2O2, the free radicals such as OH center dot derived from H2O2 can result in decrease of beta-carotene concentration. Therefore, in the production of beta-carotene by H2O2 stress, not only the level of oxidative stress, but also the activities of catalase in cells should be considered.