Spore-forming bacteria and their utilisation as probiotics

A highly acid-resistant novel strain of Lactobacillus johnsonii No. 1088 has antibacterial activity, including that against Helicobacter pylori, and inhibits gastrin-mediated acid production in mice

A novel strain of Lactobacillus johnsonii No. 1088 was isolated from the gastric juice of a healthy Japanese male volunteer, and characterized for its effectiveness in the stomach environment. Lactobacillus johnsonii No. 1088 was found to have the strongest acid resistance among several lactobacilli examined (>10% of cells survived at pH 1.0 after 2 h), and such a high acid resistance property was a specific characteristic of this strain of L. johnsonii. When cultured with various virulent bacteria, L. johnsonii No. 1088 inhibited the growth of Helicobacter pylori,Escherichia coli O-157, Salmonella Typhimurium, and Clostridium difficile, in which case its effectiveness was more potent than that of a type strain of L. johnsonii,JCM2012. In addition to its effect in vitro, L. johnsonii No. 1088 inhibited the growth of H. pylori in human intestinal microbiota-associated mice in both its live and lyophilized forms. Moreover, L. johnsonii No. 1088 suppressed gastric acid secretion in mice via decreasing the number of gastrin-positive cells in the stomach. These results taken together suggest that L. johnsonii No. 1088 is a unique lactobacillus having properties beneficial for supporting H. pylori eradication by triple therapy including the use of a proton pump inhibitor (PPI) and also for prophylaxis of gastroesophageal reflux disease possibly caused after H. pylori eradication as a side effect of PPI.

Physiology and Sporulation in Clostridium

Clostridia are Gram-positive, anaerobic, endospore-forming bacteria, incapable of dissimilatory sulfate reduction. Comprising approximately 180 species, the genus Clostridium is one of the largest bacterial genera. Physiology is mostly devoted to acid production. Numerous pathways are known, such as the homoacetate fermentation by acetogens, the propionate fermentation by Clostridium propionicum , and the butyrate/butanol fermentation by C. acetobutylicum , a well-known solvent producer. Clostridia degrade sugars, alcohols, amino acids, purines, pyrimidines, and polymers such as starch and cellulose. Energy conservation can be performed by substrate-level phosphorylation as well as by the generation of ion gradients. Endospore formation resembles the mechanism elucidated in Bacillus . Morphology, contents, and properties of spores are very similar to bacilli endospores. Sporulating clostridia usually form swollen mother cells and accumulate the storage substance granulose. However, clostridial sporulation differs by not employing the so-called phosphorelay. Initiation starts by direct phosphorylation of the master regulator Spo0A. The cascade of sporulation-specific sigma factors is again identical to what is known from Bacillus . The onset of sporulation is coupled in some species to either solvent (acetone, butanol) or toxin (e.g., C. perfringens enterotoxin) formation. The germination of spores is often induced by various amino acids, often in combination with phosphate and sodium ions. In medical applications, C. butyricum spores are used as a C. difficile prophylaxis and as treatment against diarrhea. Recombinant spores are currently under investigation and testing as antitumor agents, because they germinate only in hypoxic tissues (i.e., tumor tissue), allowing precise targeting and direct killing of tumor cells.

SporeWeb: an interactive journey through the complete sporulation cycle of Bacillus subtilis

Bacterial spores are a continuous problem for both food-based and health-related industries. Decades of scientific research dedicated towards understanding molecular and gene regulatory aspects of sporulation, spore germination and spore properties have resulted in a wealth of data and information. To facilitate obtaining a complete overview as well as new insights concerning this complex and tightly regulated process, we have developed a database-driven knowledge platform called SporeWeb (http://sporeweb.molgenrug.nl) that focuses on gene regulatory networks during sporulation in the Gram-positive bacterium Bacillus subtilis. Dynamic features allow the user to navigate through all stages of sporulation with review-like descriptions, schematic overviews on transcriptional regulation and detailed information on all regulators and the genes under their control. The Web site supports data acquisition on sporulation genes and their expression, regulon network interactions and direct links to other knowledge platforms or relevant literature. The information found on SporeWeb (including figures and tables) can and will be updated as new information becomes available in the literature. In this way, SporeWeb offers a novel, convenient and timely reference, an information source and a data acquisition tool that will aid in the general understanding of the dynamics of the complete sporulation cycle.

Probiotics from research to market: the possibilities, risks and challenges

Probiotic foods can affect large parts of the population, while therapeutic applications have a less wide scope. While commercialization routes and regulatory requirements differ for both applications, both will need good scientific support. Today, probiotics are mainly used for gastrointestinal applications, their use can easily be extended to skin, oral and vaginal health. While most probiotics currently belong to food-grade species, the future may offer new functional microorganisms in food and pharma. This review discusses the crosstalk between probiotic producers, regulatory people, medical care and healthcare workers, and the scientific community.

Defining microbiota for developing new probiotics

The human body harbors complex communities of microbes that play a prominent role in human health. Detailed characterization of the microbiota in the target population forms the basis of probiotic use. Probiotics are defined as live bacterial preparations with clinically documented health effects in humans, and independent of their genus and species, probiotic strains are unique and their beneficial properties on human health have to be assessed in a case-by-case manner. Understanding the mechanisms by which probiotics influence microbiota would facilitate the use of probiotics for both dietary management and reduction in risk of specific diseases. The development of high throughput sequencing methods has allowed metagenomic approaches to study the human microbiome. These efforts are starting to generate an inventory of bacterial taxons and functional features bound to particular health or disease status that allow inferring aspects of the microbiome's function. In the future, this information will allow the rational design of dietary interventions aimed to improve consumer's health via modulation of the microbiota.

Evaluation of Bacillus subtilis strains as probiotics and their potential as a food ingredient

Spores of Bacillus subtilis including one strain used commercially were evaluated for their potential value as a probiotic and as potential food additives. Two isolates of B. subtilis examined here were HU58, a human isolate and PXN21, a strain used in an existing commercial product. Compared to a domesticated laboratory strain of B. subtilis both isolates carried traits that could prove advantageous in the human gastro-intestinal tract. This included full resistance to gastric fluids, rapid sporulation and the formation of robust biofilms. We also showed that PXN21 spores when administered weekly to mice conferred non-specific cellular immune responses, indicative signs of the stimulation of innate immunity. Spores mixed in wholemeal biscuits were found to survive baking at 235 °C for 8 minutes with only a 1-log reduction in viability. That spores can survive the baking process offers the possibility of using spores as probiotic supplements in a range of novel food products.