Landolfo Sara, Chessa Rossella, Zara Giacomo, Zara Severino, Budroni Marilena, Mannazzu Ilaria
Department of Agriculture, Università degli Studi di Sassari, Viale Italia 39, 07100 Sassari, Italy.
Microorganisms. 2019 Sep 4;7(9):316. doi: 10.3390/microorganisms7090316.
In order to contribute to the elucidation of the biological role of carotenoids, the cellular response to hydrogen peroxide was analyzed in the red yeast . For that, the wild strain C2.5t1, that produces β-carotene, torulene, and torularhodin, and the albino mutant 200A6 that is incapable of producing detectable amounts of these carotenoids, were grown in the presence of increasing concentrations of hydrogen peroxide. In spite of the difference in carotenoid content, the two strains presented comparable resistance to the pro-oxidant that showed a minimum inhibitory concentration of 6 mM. When subject to 1 h treatment with 16 mM hydrogen peroxide the two strains increased catalase but not superoxide activity, suggesting that catalase plays a major role in cell protection in both the wild strain and the albino mutant. Moreover, C2.5t1 reduced its carotenoid content by about 40% upon hydrogen peroxide treatment. This reduction in carotenoids was in agreement with a significant decrease of the transcript levels of genes involved in carotenoid biosynthesis. Since an excess of β-carotene may enhance reactive oxygen species toxicity, these results suggest that C2.5t1 modulates carotenoid content to counteract the pro-oxidant effect of hydrogen peroxide.
为了有助于阐明类胡萝卜素的生物学作用，对红酵母中细胞对过氧化氢的反应进行了分析。为此，在过氧化氢浓度不断增加的情况下培养了野生菌株C2.5t1（其能产生β-胡萝卜素、玫红酵母红素和红酵母黄素）和白化突变体200A6（其无法产生可检测量的这些类胡萝卜素）。尽管类胡萝卜素含量存在差异，但这两种菌株对该促氧化剂表现出相当的抗性，其最低抑菌浓度为6 mM。当用16 mM过氧化氢处理1小时后，这两种菌株的过氧化氢酶活性增加，但超氧化物活性未增加，这表明过氧化氢酶在野生菌株和白化突变体的细胞保护中均起主要作用。此外，过氧化氢处理后，C2.5t1将其类胡萝卜素含量降低了约40%。类胡萝卜素的这种减少与类胡萝卜素生物合成相关基因转录水平的显著降低一致。由于过量的β-胡萝卜素可能会增强活性氧的毒性，这些结果表明C2.5t1调节类胡萝卜素含量以抵消过氧化氢的促氧化作用。
