The human gut microbiota plays a critical role in the metabolism of dietary carbohydrates. Previous studies have illustrated that marine algae oligosaccharides could be utilized and readily fermented by human gut microbiota. However, the human gut microbiota is classified into three different enterotypes, and how this may affect the fermentation processes of marine algae oligosaccharides has not been studied. Here, using in vitro fermentation and 16 S high-throughput sequencing techniques, we demonstrate that the human gut microbiota has an enterotype-specific effect on the fermentation outcomes of marine algae oligosaccharides. Notably, microbiota with a Bacteroides enterotype was more proficient at fermenting carrageenan oligosaccharides (KOS) as compared to that with a Prevotella enterotype and that with an Escherichia enterotype. Interestingly, the prebiotic effects of marine algae oligosaccharides were also found to be enterotype dependent. Altogether, our study demonstrates an enterotype-specific effect of human gut microbiota on the fermentation of marine algae oligosaccharides. However, due to the availability of the fecal samples, only one sample was used to represent each enterotype. Therefore, our research is a proof-of-concept study, and we anticipate that more detailed studies with larger sample sizes could be conducted to further explore the enterotype-specific prebiotic effects of marine oligosaccharides.

In order to obtain high quantity and quality of pigment, we investigated the blue light effects on pigment and citrinin production of Monascus in submerged fermentation. Our study showed that at the 6 th day of the fermentation, the pigment production enhanced 28.5% upon blue light illumination whereas the citrinin content decreased 79.0% when comparing with that in dark. The degradation effects of blue light on pigment and citrinin were also investigated. The degradation of pigment and citrinin were followed a first-order reaction kinetics. The half lives of citrinin and pigment were 4.7% and 47% of those under the darkness, respectively. Although the pigment was unstable under blue light illumination, the production of pigment still increased dramatically, which further implied that the blue light, maybe as a signal factor, stimulated the pigment accumulation. Higher degradation rate upon blue light seems to be the dominant factor that contributed to the lower citrinin content obtained from blue light assisted fermentation.

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