Isolation of Monascus purpureus HC-5 and Optimization of Solid-State Fermentation for High-Yield Pigment Production

<i>Monascus</i> pigments (MPs) are valuable natural colorants, but their industrial production is often hampered by scarce high-yield strains and inefficient processes. In this study, a novel MPs-producing strain was isolated from red yeast rice and named as <i>Monascus purpureus</i> HC-5. This strain exhibited notable hydrolase activities, indicating a high efficiency in substrate utilization. In addition, using rice as the optimal substrate, the key parameters of solid-state fermentation were optimized. Response surface analysis revealed that soaking time and temperature were the most critical influencing factors. The optimal combination conditions were an inoculum size of 8.91%, a soaking time of 13.59 h, and a temperature of 32 °C. Under these optimized conditions, the MPs yield reached 2185 ± 255.7 U/g, which displayed an approximately four-fold increase compared to the initial unoptimized process. Briefly, this study identified a strain of <i>Monascus purpureus</i> and optimized its solid-state fermentation conditions, which significantly increased the yield of MPs. This provides an important theoretical basis and scientific evidence for the large-scale industrial production of MPs.