Genetic responses to adding nitrates to improve hydrophilic yellow pigment in Monascus fermentation.

Zhenfeng Huang, Tingting Hu, Shanzhong Yang, Xiaofei Tian, Zhenqiang Wu

Applied microbiology and biotechnology 2023 Feb

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Nitrates can stimulate the biosynthesis of hydrophilic yellow pigments (HYPs) in Monascus ruber CGMCC 10910. To explore the molecular mechanisms whereby nitrates (NaNO3 and NH4NO3) regulate HYP production, an integrated transcriptomic and proteomic analysis was conducted in this study. Nitrate addition led to an approximately 75% higher HYP production compared with the untreated group, especially compounds Y3 and Y4. Comparative transcriptomic analysis found that mpigsA, H, K, L, and P genes involved in yellow pigment biosynthesis were significantly upregulated. In addition, pigment biosynthesis-related (carbon catabolism, amino acid metabolism, polyketide synthesis, and fatty acid metabolism) genes were upregulated to provide precursors and energy for HYP biosynthesis and cell growth. Secretion-related (cytomembrane ergosterol biosynthetic, and transport) pathways were also noticeably regulated to accelerate transmembrane transport of HYPs. Meanwhile, proteomic analysis showed that nitrates improved the protein expression of hybrid polyketide synthase-nonribosomal peptide synthetase, oxidoreductase, glucoamylase, endo-1,4-beta-xylanase, O-acetylhomoserine, and isocitrate lyase to enhance HYP production. These findings demonstrated the regulatory mechanism of nitrates for enhancing HYP production in Monascus. KEY POINTS: • Nitrates stimulated the biosynthesis of Monascus hydrophilic yellow pigments (HYPs) • Nitrates affected transcriptional level of pigment biosynthesis- and transport genes • Increased expression of hybrid PKS-NRPS and transporters promoted production of HYPs. © 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Citation

Zhenfeng Huang, Tingting Hu, Shanzhong Yang, Xiaofei Tian, Zhenqiang Wu. Genetic responses to adding nitrates to improve hydrophilic yellow pigment in Monascus fermentation. Applied microbiology and biotechnology. 2023 Feb;107(4):1341-1359