Bacillus subtilis culture (S. cerevisiae)
Also known as: Bacillus subtilis, Saccharomyces cerevisiae, probiotic bacterium, spore-forming Bacillus strain, yeast, brewer’s yeast, baker’s yeast
Overview
Bacillus subtilis is a Gram-positive, rod-shaped, spore-forming bacterium naturally found in soil. It is widely used as a probiotic due to its ability to form resilient spores, allowing it to survive harsh gastrointestinal conditions. Saccharomyces cerevisiae, commonly known as baker’s or brewer’s yeast, is a yeast species used in fermentation, baking, and as a source of yeast fractions or extracts in supplements. Bacillus subtilis is used to improve gut microbiota balance, enhance nutrient absorption, and support immune function, while Saccharomyces cerevisiae culture or yeast fractions are used to improve gut health, modulate immunity, and sometimes as a source of bioactive compounds. Research is moderate to advanced in animal studies, but still emerging in human clinical research.
Benefits
Bacillus subtilis supplementation at doses of 0.1–0.5 × 10^6 cfu/g has been shown to improve feed conversion efficiency (FCE) and average daily gain (ADG) in broiler chickens, indicating enhanced growth performance and nutrient utilization. Saccharomyces cerevisiae-derived yeast fractions combined with Bacillus products have demonstrated positive effects on health and growth parameters in animal models. Immunomodulatory effects via yeast beta-glucans and Bacillus metabolites have also been reported, potentially enhancing host defense mechanisms. Most evidence is from poultry and livestock, with limited human data suggesting potential gut microbiota modulation. Improvements in FCE and ADG in poultry were statistically significant with moderate effect sizes.
How it works
Bacillus subtilis spores germinate in the gut, producing enzymes and antimicrobial compounds that modulate gut microbiota and enhance digestion. Saccharomyces cerevisiae yeast fractions provide cell wall components (beta-glucans, mannans) that interact with immune cells, modulating inflammatory responses. This involves gut microbiota modulation, enhancement of intestinal barrier function, and immune system stimulation. Molecular targets include pattern recognition receptors (e.g., dectin-1 for beta-glucans), gut epithelial cells, and microbial populations. Bacillus subtilis spores survive gastric acidity and colonize or transiently persist in the intestine, while yeast cell wall components act locally in the gut with limited systemic absorption.
Side effects
Both Bacillus subtilis and Saccharomyces cerevisiae are generally recognized as safe (GRAS) in food and feed applications. Common side effects are rare, but some individuals may experience gastrointestinal discomfort. Uncommon side effects include possible mild allergic reactions in yeast-sensitive persons. Rare side effects include very rare cases of infection reported with probiotic use in immunocompromised patients, though Bacillus subtilis is considered low risk. No significant drug interactions have been documented. Caution is advised in severely immunocompromised individuals. Limited data are available for pregnant or lactating women, but they are generally considered safe.
Dosage
For Bacillus subtilis in animal studies, 0.1 × 10^6 cfu/g feed has shown benefits. Human dosing varies widely, with typical probiotic doses ranging from 10^8 to 10^10 cfu/day. Animal studies suggest 0.1–0.5 × 10^6 cfu/g feed, but human doses are not well established. There is no established upper limit, and doses up to 10^10 cfu/day are commonly used without adverse effects. Continuous daily administration is recommended for sustained effects. Spores for Bacillus subtilis ensure stability, while yeast fractions are typically in powder or extract form. Spores resist gastric acid, and yeast components act locally in the gut. No specific cofactors are required.
FAQs
Is Bacillus subtilis culture combined with Saccharomyces cerevisiae effective?
Evidence from animal studies suggests synergistic benefits on growth and health parameters when combined.
Are these supplements safe for human consumption?
Generally yes, but human-specific clinical data are limited.
When can benefits be expected?
In animals, benefits appear within weeks; human data are insufficient for precise timing.
Can these supplements replace antibiotics or other treatments?
They may support gut health but are not substitutes for medical treatments.
Research Sources
- https://www.appliedanimalscience.org/article/S2590-2865(23)00051-4/pdf – This Applied Animal Science study evaluates Saccharomyces cerevisiae-derived yeast fraction and Bacillus products. Controlled trials showed improved health and growth parameters in animal models when yeast fractions and multispecies Bacillus products were used alone or combined, demonstrating statistical significance with adequate sample sizes, but requires independent verification for human applicability.
- https://www.degruyterbrill.com/document/doi/10.1515/opag-2022-0123/html – This meta-analysis on Bacillus spp. in broiler chickens systematically reviews dietary Bacillus spp. supplementation in broilers. The study found that Bacillus at 0.1–0.5 × 10^6 cfu/g significantly improved feed conversion efficiency and average daily gain, but is limited by its focus on animal models, making human relevance indirect.
- https://www.mdpi.com/2076-2607/9/1/112 – This MDPI study provides mechanistic insights into Bacillus subtilis stress response and gene regulation. It supports understanding of probiotic function by detailing Bacillus subtilis gene expression and modeling, offering useful mechanistic context, though it is not a clinical trial.
- https://portlandpress.com/essaysbiochem/article/65/2/277/228841/Harnessing-the-yeast-Saccharomyces-cerevisiae-for – This resource discusses the use of Saccharomyces cerevisiae, highlighting its applications and benefits. It provides a broad overview of how this yeast is harnessed for various purposes, including its role in health and nutrition.