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BACILLUS SUBTILIS

Also known as: B. subtilis, hay bacillus, grass bacillus, Bacillus subtilis

Overview

Bacillus subtilis is a spore-forming, rod-shaped bacterium naturally found in soil and the gastrointestinal tract of humans and animals. It is widely recognized as a probiotic due to its exceptional ability to survive harsh gastric conditions and effectively colonize the gut. Primarily, it is utilized as a dietary supplement to enhance gut health, bolster immune function, and in animal husbandry, it plays a crucial role in improving feed efficiency and preventing intestinal diseases. Its key characteristic is its spore-forming ability, which grants it remarkable resistance to heat and stomach acid, ensuring its survival and delivery to the intestines where it can germinate and exert its beneficial effects. Furthermore, B. subtilis produces various enzymes and antimicrobial compounds that actively modulate the gut microbiota. Research on B. subtilis is moderate to advanced, with numerous randomized controlled trials and meta-analyses, particularly in animal models, and a growing body of evidence in human studies.

Benefits

Bacillus subtilis offers several evidence-based benefits, particularly in animal health, with emerging potential in human applications. The most robust evidence points to its efficacy in improving gut health and feed conversion, especially in poultry. Meta-analyses in broiler chickens have consistently shown that B. subtilis supplementation significantly improves the feed conversion ratio (FCR) and reduces necrotic enteritis (NE) lesion scores, indicating enhanced intestinal health and disease resistance. While no significant effect on mortality was noted in these studies, the improvements in FCR are clinically significant for animal agriculture. These benefits are observed within weeks of supplementation. Secondary effects include potential modulation of bone mineral density and structure, as suggested by systematic reviews in rodent models where probiotic mixtures (including Bacillus spp.) improved bone health. However, B. subtilis-specific data for bone health is less clear, and this benefit requires further investigation. The strength of evidence is high for poultry, based on multiple high-quality meta-analyses, while evidence for human-specific benefits is still emerging and requires more dedicated human randomized controlled trials.

How it works

Bacillus subtilis exerts its beneficial effects primarily through the modulation of gut microbiota and direct antimicrobial actions. Its spore-forming nature allows it to survive the acidic environment of the stomach, reaching the intestines intact where it germinates. Once in the gut, B. subtilis modulates the microbiota by competitively excluding pathogenic bacteria, such as Clostridium perfringens, preventing their colonization and proliferation. It also produces a variety of antimicrobial peptides and enzymes that directly inhibit the growth of harmful bacteria. Furthermore, B. subtilis interacts with the host's immune system, enhancing intestinal barrier function and promoting immune modulation. Its known molecular targets include pathogenic bacteria in the gut and host immune cells, contributing to an overall healthier gut environment and improved host defense.

Side effects

Bacillus subtilis is generally recognized as safe (GRAS) and has a long history of use in food and dietary supplements. Common side effects are rare and typically mild, occasionally including transient gastrointestinal discomfort such as bloating or gas in sensitive individuals. Uncommon and rare side effects are extremely infrequent; however, there have been very rare reports of infection in severely immunocompromised individuals, although this is not a common occurrence in the general population. There are no significant drug interactions reported with Bacillus subtilis. Contraindications primarily involve caution in immunocompromised patients due to the theoretical risk of infection. For special populations, such as pregnant women and children, data on B. subtilis is limited; while generally considered safe, comprehensive clinical data for these groups is sparse, and consultation with a healthcare professional is advisable. Overall, its safety profile is favorable for healthy individuals.

Dosage

The minimum effective dose of Bacillus subtilis varies depending on the specific application and formulation. In animal studies, typical effective doses range from 10^7 to 10^9 Colony Forming Units (CFU) per day. For poultry, doses around 10^8 CFU per gram of feed have been shown to be effective in improving feed conversion and gut health. For human use, optimal dosage ranges vary widely depending on the specific product and intended purpose, as formulations can differ significantly. There is no well-defined maximum safe dose, as high doses are generally well tolerated due to the spore-forming nature of the bacterium. Daily administration is recommended for sustained benefits. Spore-based formulations are preferred due to their enhanced stability and ability to survive gastric acid, ensuring delivery of viable bacteria to the intestines. No specific cofactors are required for its efficacy, though prebiotics may enhance its colonization and beneficial effects.

FAQs

Is Bacillus subtilis safe for daily use?

Yes, Bacillus subtilis is generally recognized as safe (GRAS) and is considered safe for daily consumption by healthy individuals. Side effects are rare and usually mild.

How quickly does it work?

Benefits, particularly in gut health and feed efficiency, can typically be observed within a few weeks of consistent supplementation, as shown in animal studies.

Can it replace antibiotics in animals?

Bacillus subtilis shows promise as an effective alternative or adjunct to antibiotics for improving gut health and preventing infections like necrotic enteritis in poultry, reducing the need for conventional antibiotics.

Does it cause infections?

Infections caused by Bacillus subtilis are extremely rare and have primarily been reported in severely immunocompromised individuals. It is generally not a concern for healthy people.

Research Sources

https://pubmed.ncbi.nlm.nih.gov/38776185/?fc=None&ff=20240523024845&v=2.18.0.post9+e462414 – This meta-analysis of randomized controlled trials in poultry found that Bacillus subtilis supplementation significantly improved feed conversion ratio and reduced necrotic enteritis lesion scores. The study highlights the efficacy of B. subtilis in enhancing gut health and performance in broiler chickens, although it noted no significant effect on mortality.
https://www.tandfonline.com/doi/abs/10.1080/03079457.2024.2359596 – This research, likely a part of the same meta-analysis as the previous entry, further supports the benefits of Bacillus subtilis in poultry. It details how B. subtilis improves feed efficiency and gut integrity, contributing to better growth performance and disease resistance in broiler chickens, reinforcing its role as a valuable probiotic in animal agriculture.
https://academic.oup.com/jbmr/article/40/1/100/7901044 – This systematic review and meta-analysis in rodents investigated the effects of probiotic supplementation, including Bacillus species, on bone mineral density. While it indicated that probiotics generally improved bone health in rodents, the specific effects attributable solely to Bacillus subtilis were less clear due to heterogeneity in probiotic strains and doses across studies.
https://www.degruyterbrill.com/document/doi/10.1515/opag-2022-0123/html – This meta-analysis focused on the impact of dietary Bacillus species in various animal studies. It concluded that dietary Bacillus spp. generally improved feed intake and feed conversion efficiency in animals. However, this study covered a broad category of Bacillus species, meaning the findings are not exclusively specific to Bacillus subtilis but indicate a general beneficial trend for the genus.