Enhancement of Monascus yellow pigments production by activating the cAMP signalling pathway in Monascus purpureus HJ11
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(2020) 19:224 Liu et al. Microb Cell Fact https://doi.org/10.1186/s12934-020-01486-y
Open Access
RESEARCH
Enhancement of Monascus yellow pigments production by activating the cAMP signalling pathway in Monascus purpureus HJ11 Jiawei Liu1, Yun Du1, Hongmin Ma2, Xiaolin Pei3 and Mu Li1*
Abstract Background: Monascus azaphilone pigments (MonAzPs), which were produced by Monascus species, have been used as important food colorant and food supplements for more than one billion people during their daily life. Moreover, MonAzPs recently have received more attention because of their diverse physiological activities. However, the high microbial production of MonAzPs is still not always guaranteed. Herein, the aim of this study was to develop an efficient biotechnological process for MonAzPs production. Results: In this study, exogenous cyclic adenosine monophosphate (cAMP) treatment not only induced MonAzPs production, but also stimulated the expression of a cAMP phosphodiesterase gene, named as mrPDE, in M. purpureus HJ11. Subsequently, MrPDE was identified as a cAMP phosphodiesterase by in vitro enzymatic reaction with purified enzyme. Further, a gene knockout mutant of mrPDE was constructed to verify the activation of cAMP signalling pathway. Deletion of mrPDE in M. purpureus HJ11 improved cAMP concentration by 378% and enhanced PKA kinase activity 1.5-fold, indicating that activation of cAMP signalling pathway was achieved. The ΔmrPDE strain produced MonAzPs at 8563 U/g, with a 2.3-fold increase compared with the WT strain. Moreover, the NAPDH/NADP+ ratio of the ΔmrPDE strain was obviously higher than that of the wild type strain, which led to a higher proportion of yellow MonAzPs. With fed-batch fermentation of the ΔmrPDE strain, the production and yield of MonAzPs achieved 332.1 U/ mL and 8739 U/g. Conclusions: A engineered M. purpureus strain for high MonAzPs production was successfully developed by activating the cAMP signalling pathway. This study not only describes a novel strategy for development of MonAzPs-producing strain, but also provides a roadmap for engineering efforts towards the production of secondary metabolism in other filamentous fungi. Keywords: Monascus purpureus, Monascus azaphilone pigments, cAMP signaling pathway, cAMP phosphodiesterase, Gene knockout, Fed-batch fermentation
*Correspondence: [email protected] 1 Hubei International Scientific and Technological Cooperation Base of Traditional Fermented Foods, Key Laboratory of Environment Correlative Dietology, College of Food Science and Technology, Huazhong Agricultural University, Hubei Province, Wuhan 430070, China Full list of author information is available at the end of the article
Background Monascus azaphilone pigments (MonAzPs) are large group of secondary metabolites produced via polyketide biosynthesis mainly by Monascus spp. strains [1, 2]. MonAzPs have been generally classified into yellow, orange, and red pigment subclasses on the basis of color [3, 4]. MonAzPs have been extensively used as natural food coloring agen
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