Effects of Rhodotorula mucilaginosa on the Immune Function and Gut Microbiota of Mice

Abstract

As a dominant species among marine yeasts, Rhodotorula benthica accounts for ~50% of all marine yeasts. Rhodotorula is rich in a variety of bioactive substances and commonly used in the production of carotenoids by microbial fermentation and is worth developing. Therefore, the present study used a strain of Rhodotorula mucilaginosa isolated from the coastal waters of the South China Sea as the target yeast to investigate its impact on the immune function and gut microbiota of mice. A total of 200 mice were randomly divided into gavage groups and control group and garaged for 30 consecutive days at different concentration. Samples were collected on day 15 and day 30 of gavage administration. The results showed that R. mucilaginosa ZTHY2 could increase the thymus and spleen indices of mice, and its effect on the thymus index was more significant after long-term gavage administration. Short-term (15 days) gavage administration of R. mucilaginosa suspension enhanced delayed hypersensitivity in mice, increased serum IgG, IgA, and IL-2. Long-term (30 days) gavage administration of R. mucilaginosa suspension significantly enhanced the phagocytosis of macrophages in mice and significantly increased serum TNF-α and INF-γ. R. mucilaginosa ZTHY2 altered the structure of the gut microbiota of mice at the phylum and genus levels, leading to an increased relative abundance of Firmicutes and Lactobacillus and a decreased relative abundance of Bacteroidetes. This strain increased the beneficial intestinal bacteria and reduced the harmful intestinal bacteria in mice. This study provides experimental evidence and lays the foundation for the future development and application of this strain as a microecological source of carotenoids.

Yeast Rhodoturula glutinis as a modulator of innate immune and oxidative stress-related genes in Oreochromis niloticus cultured in a Biofloc system

“…MOS participates in the increased villus integrity and promotes the efficiency of digestion and absorption as well as the energy and building protein produced from β-glucan degenerated by glucanases in the digestive gland (Yuji-Sado et al 2015, Gelibolu et al 2018, Chen et al 2019, Yun et al 2021. Our results agree with other studies, where strains of the Rhodotorula genus, such as R. benthica and R. mucilaginosa, improved the growth of cultivated organisms (Wang et al 2015, Chen et al 2019, Ge et al 2021. Regarding FCR, the lowest value was obtained in the BFT+Rg treatment; this agrees with Chen et al (2019), who, when supplementing the diet of Oreochromis niloticus with 1% hydrolyzed R. mucilaginosa reported a value of 1.12.…”

“…In addition, its ability for artificial colonization of the intestinal host has been demonstrated (Ueno et al 2011, Navarrete & Tovar-Ramírez 2014. Therefore, numerous studies have evaluated the effects of live yeast or its subcomponents and derivatives alone or in combination on the growth of aquatic animals (Navarrete & Tovar-Ramírez 2014, Chen et al 2019, Ge et al 2021. Cells of Rhodotorula are rich in several nutrients like E and B vitamins, amino acids, proteins, lipids, carotenoids, and MOS (Chen et al 2019, Schafberg et al 2020).…”

“…They are recognized by different cell receptors of macrophages, dendritic cells, and neutrophils. The interaction with said receptors induces the production of various cytokines (Navarrete & Tovar 2014, Ching et al 2021, Ge et al 2021.…”

“…The probiotic properties of yeasts in aquaculture have been scarcely studied. However, antioxidant and immunostimulant properties provide nutrients such as E and B vitamins, amino acids, proteins, mannanoligosaccharides (MOS), and lipids (Navarrete & Tovar-Ramírez 2014, Schafberg et al 2020, Ge et al 2021.…”

“…Besides, some species provide a high content of carotenoids (Schafberg et al 2020, Ge et al 2021. Another advantage of using yeasts is that they are not affected by antibacterial compounds, and some strains have antagonistic activities against pathogenic bacteria (Rima et al 2012, Navarrete & Tovar-Ramírez 2014, Caruffo et al 2015.…”