红曲菌mrfA缺失突变株发酵过程中的生理生化特征

Study on the physiological and biochemical characteristics of the mrfA-deleted mutant of Monascus ruber during the fermentaion process

为了解红曲菌G蛋白信号调节子mrfA缺失突变株发酵过程中的生理生化特征,测定了该突变菌株在液态发酵过程中的生物量、葡萄糖利用率、pH值、蛋白酶、几丁质酶、过氧化氢酶、超氧化物歧化酶、谷胱甘肽过氧化物酶的活性。与原始菌株红色红曲菌M7相比较,mrfA缺失突变株在生长后期生物量会明显减少,在发酵过程中葡萄糖消耗率、蛋白酶和几丁质酶均高于出发菌株,其中蛋白酶活力在第6天达到最高。与此同时,mrfA缺失突变株的过氧化氢酶、超氧化物歧化酶、谷胱甘肽过氧化物酶酶活也均高于出发菌株M7。这些结果初步表明mrfA缺失突变株与原始菌株相比自溶特征更加明显,推测蛋白酶是诱发菌体自溶的主要水解酶,超氧化物歧化酶是其防御氧化应激的主要酶。研究结果为进一步理解mrfA介导的红曲菌自溶机理奠定了基础。

In this paper, conventional analyses on biomass decline, glucose consumption rate, pH value and the enzyme activities, such as protease, chitinase, catalase, superoxide dismutase and glutathione peroxidases, were in- vestigated for understanding the physiological and biochemical characteristics during the submerged fermentation of mrfA deletion mutant of Monascus tuber M7. Compared with the original strain M7, the biomass declined more quick- ly. During the whole fermentation, glucose consumption rate and the activities of protease/chitinase were all higher than those of M7. Obviously, the highest activity of protease occurred on Day 6. At the same time, activities of cata- lase/superoxide dismutase/glutathione peroxidases of mrfA deletion mutant were also higher than those of M7. All these results showed that mrfA deletion mutant showed typical autolysis characteristics in the growth process, which might due to high protease activity. Superoxide dismutase was the main antioxidant enzyme to cope with reactive oxygen species （ROS） damage. This study laid a foundation for further understanding of the autolysis mechanism of Monascus spp.