Nutrient L-Alanine-Induced Germination of Bacillus Improves Proliferation of Spores and Exerts Probiotic Effects in vitro and in vivo

Spore germination and lactic acid combined treatment: A new processing strategy for the shelf-life extension of instant wet noodles

Bacillus amyloliquefaciens (BAM) was identified as the predominant spoilage bacteria in instant wet noodles (IWNs). The utilization of industrial acid treatment as a long shelf-life strategy resulted in reduced consumer acceptance due to the acidic taste of the products. This study proposed a processing strategy that integrated spore germination (SG) and lactic acid (LA) treatment to effectively reduce the spore survival rate and extend the shelf life of IWNs. L-histidine, d-glucose, and sodium chloride were highly efficient and safe germinants for BAM spores. In IWNs, compound germinants (1.0 % L-histidine, 0.5 % d-glucose, and 1.0 % sodium chloride) boosted the SG rate by 3.61 times. With synergistic LA treatment, the spore lethality increased by 34.41 % -41.68 %. Under the SG and reduced acid-heat conditions of pH 2.30-2.50, the mortality of spores could reach 92.00 %-93.17 %, which was 14.11 %-15.28 % higher than the industrial acid-heat condition of pH 2.10. DPA, ATP, and membrane potential showed that germinants reduced the spore membrane permeability and promoted the occurrence of spore membrane damage under acid-heat conditions. Moreover, this strategy significantly extended the shelf-life of IWNs by 3.00-5.50 times and controlled the pH ≥ 5.50. Additionally, it improved color, texture, and overall sensory evaluation. Accordingly, this strategy solved the contradiction between the long shelf-life of IWNs and the unacceptable acidification in industrial production.

L-Alanine promotes anti-infectious properties of Bacillus subtilis S-2 spores via the germination receptor gerAA

Bacillus species, which have two cell-type forms (vegetative cells and spores), demonstrate a variety of probiotic functions in animal feed additives and human nutrition. We previously found that the probiotic effect of Bacillus subtilis S-2 spores with high germination response to L-alanine was specifically enhanced by the L-alanine pretreatment. The germination response of Bacillus is highly associated with the germination receptors of spores. However, how L-alanine-induced germination of spores exerts anti-infectious effect in epithelial cells remains unclear. In this study, we constructed the mutant strain of B. subtilis S-2 with germination receptor gerAA knockout to further explore the role of spore germination in resisting pathogen infection to cells. The differential probiotic effects of B. subtilis S-2 and S-2^ΔgerAA spores pretreated with L-alanine were evaluated in intestinal porcine epithelial cells (IPEC-J2) or Caco2 cells infected with enterotoxigenic Escherichia coli (ETEC) or following IL-1β stimulation. The results showed that the germination response of the S-2^ΔgerAA spores to L-alanine was significantly reduced. Compared with the S-2^ΔgerAA spores, the L-alanine-induced germination of B. subtilis S-2 spores significantly increased the activity of anti-adhesion of ETEC to IPEC-J2 cells and reduced the expression of inflammatory factors and cell receptors. L-alanine induction also significantly promoted the expression of autophagy-related proteins in the B. subtilis S-2 spores. These findings demonstrate that the gerAA germination receptor is essential for the probiotic function of Bacillus spores and that L-alanine treatment promotes the anti-infectious properties of the germinated spores in porcine intestinal epithelial IPEC-J2 cells. The result suggests the importance of germination receptor gerAA in helping spore germination and enhancing anti-infectious activity. The findings in the study benefit to screening of potential Bacillus probiotics and increasing probiotic efficacy induced by L-alanine as an adjuvant.

W D, U. M K, S.D K. Bacillus Coagulans and its Spore as Potential Probiotics in the Production of Novel Shelf- Stable Foods

The synbiotic foods with therapeutic activities have been beneficial to gut health and immunity development, including Bacillus coagulans as the probiotic microorganism. It is preferred over other lactic acid bacteria (LAB) as it can produce spores. It is grown in the pH range of 5.5 to 6.2 and releases spores at 37 °C. These microbial spores can withstand environments with high temperatures, acidic conditions, and salinity, making it a viable probiotic organism for production of novel shelf-stable foods. It has become an essential ingredient in the functional food industry due to its probiotic characteristics and great resistance to stressful conditions. For extensive commercial use and a wide range of food applications, apart from probiotic characteristics, a probiotic organism must be cost-effective, convenient and remain viable throughout the processing, storage and consumption. The non-spore- forming lactic acid bacteria can be utilized to make probiotic products and fermented dairy products under controlled processing and storage conditions. The spore- forming probiotic organism can be delivered into the human gut through novel food products derived from cereals, legumes, fruits and vegetables, confectionery products, and meat and non-dairy products. This has led to the development of convenient and shelf-stable non-dairy probiotics. These non-dairy-based probiotics are cheaper, resilient against various processing conditions, high in bioactive components, and can mitigate the risk of lifestyle diseases and reduce. Further, lactose intolerance is associated with the consumption of dairy probiotics. Therefore, this review aimed to assess the utilization of probiotic Bacillus coagulans spores in emerging shelf-stable novel non-dairy products with probiotic potential.

Bacillus-derived probiotics: metabolites and mechanisms involved in bacteria-host interactions

Bacillus probiotics have a sporulation capacity that makes them more suitable for processing and storage and for surviving passage through the gastrointestinal tract. The probiotic functions and regulatory mechanisms of different Bacillus have been exploited in many reports, but little is known about how various Bacillus probiotics perform different functions. This knowledge gap results in a lack of specificity in the selection and application of Bacillus. The probiotic properties are strain-specific and cell-type-specific, and are related to the germination potential and to the diversity of metabolites produced following intestinal germination, as this causes the variation in probiotic function and mechanisms. In this review, we discuss the Bacillus metabolites produced during germination and sporulation in the GI tract, as well as possible processes affecting intestinal homeostasis. We conclude that the oxygen-capturing capability and the production of antimicrobials, exoenzymes, competence and sporulation factors (CSF), exopolysaccharides, lactic acid, and cell components are specifically associated with the functional mechanisms of probiotic Bacillus. The aim of this review is to guide the screening of potential Bacillus strains for probiotics and their application in nutrition research. The information provided will also promote further research on Bacillus-derived functional metabolites in human nutrition.