Unlocking the Potential of Bacillus subtilis: A Comprehensive Study on Mycotoxin Decontamination, Mechanistic Insights, and Efficacy Assessment in a Liquid Food Model

Mycotoxin detoxification by microorganisms offers a specific, economical, and environmentally sustainable alternative to physical/chemical methods. Three strains of B. subtilis, isolated from poultry farm environments and recognized by EFSA as safe in animal nutrition for all animal species, consumers, and the environment, were screened for their ability to remove mycotoxins. All of them demonstrated mycotoxin-dependent removal efficacy, being very effective against ZEA and its analogues (α- and β-ZOL, α- and β-ZAL, and ZAL) achieving up to 100% removal within 24 h under aerobic, anaerobic, and restrictive growth conditions with toxins as the sole carbon source. ZEA removal remained effective across a wide range of pH values (5-8), temperatures (20-40 °C), and at high toxin concentrations (up to 10 µg/mL). Additionally, up to 87% ZEA removal was achieved after 48 h of incubation (30 °C) of the strains in a contaminated liquid food model containing 1 µg/mL of the toxin. Mechanistic studies suggest that ZEA detoxification involves metabolic processes rather than physical adsorption or entrapment into bacterial cells. Enzymatic activities within the bacterial cells or associated with their cell walls likely play a role in the metabolization of the toxin. Interestingly, it has been observed that growth conditions and culture media can influence the metabolization and/or conjugation of the toxin, which can result in the production of various metabolites. Further investigation is needed to identify these metabolites and assess their safety.

Supplementation of Bacillus subtilis GM5 enhances broiler body weight gain and modulates cecal microbiota

We investigated the effect of the strain Bacillus subtilis GM5 on growth, feed conversion, and the composition of cecum microbiota in broiler chickens. Half of which received a control diet, while the other half was fed a diet supplemented with GM5 spores. Cecal contents on days 1, 10, and 42 were subjected to metataxonomic analysis. Principal Component Analysis showed that the control and probiotic groups formed three separate clusters, indicating changes, which occurred gradually in microbial communities. On day 1, Firmicutes (53.87-57.61%) and Proteobacteria (43.77-38.93%) were prevalent in both groups, whereas samples of days 10 and 42 were predominantly occupied by Firmicutes (54.55-81.79%) and Bacteroidetes (26.94-30.45%). In the group of chickens treated with probiotic, the average daily gain in body weight was higher, while feed conversion decreased by 1.44%. A surge in the presence of beneficial bacteria of the Ruminococcaceae family was observed. The introduction of the probiotic led to an elevated Firmicutes/Bacteroidetes ratio, which positively correlated with chickens' bodyweight (Spearman ρ = 1.0, P < 0.05). Supplementing broiler feed with B. subtilis GM5 spores leads to improved feed intake and digestibility, which is paramount in reducing the cost of the final product. Thus, the probiotic strain GM5 modulates the cecal microbiota of broiler chickens and increases microbial diversity, which is well exhibited on the 42nd day.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-020-02634-2.