College of Life Science, Yangtze University, Jingzhou, 434025, Hubei, China.
College of Animal Science, Yangtze University, Jingzhou, 434025, Hubei, China.
Appl Microbiol Biotechnol. 2019 Oct;103(20):8393-8402. doi: 10.1007/s00253-019-10114-8. Epub 2019 Sep 9.
The influence of pH on the biosynthesis of orange Monascus pigments (OMPs) in Monascus ruber M7 was investigated. Under acidic fermentation conditions, pigment mixtures predominantly rich in OMPs were obtained. HPLC analysis revealed the presence of four orange components (O1-O4) and four yellow components (Y1-Y4) in the mixtures, and the dominant ones were O1 and O3, which accounted for 56.0% to 75.9% of the total pigments in the pH range 3-6. Subsequently, O1 and O3 were identified by LC-DAD-ESI/MS as Rubropunctatin and Monascorubrin, respectively. The yield of OMPs was observed to be inversely dependent on pH. At pH 3, large amounts of OMPs with high purity (79.1%) were accumulated. A real-time quantitative PCR analysis revealed that the expression of genes related to the biosynthesis of OMPs in M. ruber M7 was upregulated at acidic pH as compared to neutral pH, and the variation in the level of expression of these genes with pH was consistent with the production of OMPs. These results indicated that the large accumulation of OMPs under acidic condition involved the acidic pH-induced transcription of genes related to the biosynthesis of OMPs. These results would contribute towards the development of an efficient technology for large-scale production of OMPs.
研究了 pH 值对红曲菌 M7 中橙色桔青霉素（OMP）生物合成的影响。在酸性发酵条件下，获得了主要富含 OMP 的色素混合物。HPLC 分析表明，混合物中存在四种橙色成分（O1-O4）和四种黄色成分（Y1-Y4），其中主要成分是 O1 和 O3，它们在 pH 值为 3-6 范围内占总色素的 56.0%-75.9%。随后，通过 LC-DAD-ESI/MS 将 O1 和 O3 鉴定为 Rubropunctatin 和 Monascorubrin。OMP 的产量与 pH 值呈负相关。在 pH 3 时，大量高纯度（79.1%）的 OMP 积累。实时定量 PCR 分析表明，与中性 pH 值相比，红曲菌 M7 中与 OMP 生物合成相关的基因在酸性 pH 值下表达上调，这些基因的表达水平随 pH 值的变化与 OMP 的产生一致。这些结果表明，酸性条件下 OMP 的大量积累涉及与 OMP 生物合成相关的基因在酸性 pH 诱导下的转录。这些结果将有助于开发大规模生产 OMP 的有效技术。
