A comparative analysis of monascin and ankaflavin biosynthesis in Monascus purpureus and its albino variant

Red mold rice (RMR), a functional food ingredient, is produced via Monascus spp. fermentation, a process that yields a diverse range of bioactive compounds, most notably the Monascus yellow pigments monascin and ankaflavin. This study provides the first report of spontaneous albinism in Monascus species. Although the specific mechanisms and conditions triggering the transition to albino strains remain to be definitively elucidated, our analyses reveal that the albino strain of Monascus purpureus exhibits a faster growth rate and significantly lower yellow pigment production compared to the wild-type strain. This suggests that the emergence of albino strains poses a considerable risk to the stability of industrial M. purpureus cultures. Furthermore, comparative analysis of gene expression associated with monascin and ankaflavin biosynthesis between M. purpureus wild-type and albino strains under various culture conditions indicates that the malate-citrate shuttle, specifically the mitochondrial dicarboxylate carrier (DIC), may play a critical role in yellow pigment biosynthesis. The comparative analysis also revealed significant correlations among glyceraldehyde-3-phosphate dehydrogenase (GAPDH), DIC, mrpigH expression, and overall yellow pigment production, suggesting a potential metabolic approach for enhancing M. purpureus pigment biosynthesis. Ultimately, given the profound differences in pigment yield and fermentation characteristics, these findings demonstrate that the occurrence of spontaneous albinism represents not only a critical, previously overlooked risk factor for industrial M. purpureus production, but also a possible approach for elucidating the regulatory mechanisms of M. purpureus secondary metabolism. KEY POINTS: • This study provides the first report of spontaneous albinism in Monascus species. • Expression of GAPDH, DIC, and mrpigH, as well as MS/AK production were significantly correlated. • Albino strain represents an overlooked risk factor for industrial M. purpureus production.