Probiotic properties of Bacillus subtilis DG101 isolated from the traditional Japanese fermented food nattō

Abstract

Spore-forming probiotic bacteria offer interesting properties as they have an intrinsic high stability, and when consumed, they are able to survive the adverse conditions encountered during the transit thorough the host gastrointestinal (GI) tract. A traditional healthy food, nattō, exists in Japan consisting of soy fermented by the spore-forming bacterium Bacillus subtilis natto. The consumption of nattō is linked to many beneficial health effects, including the prevention of high blood pressure, osteoporosis, and cardiovascular-associated disease. We hypothesize that the bacterium B. subtilis natto plays a key role in the beneficial effects of nattō for humans. Here, we present the isolation of B. subtilis DG101 from nattō and its characterization as a novel spore-forming probiotic strain for human consumption. B. subtilis DG101 was non-hemolytic and showed high tolerance to lysozyme, low pH, bile salts, and a strong adherence ability to extracellular matrix proteins (i.e., fibronectin and collagen), demonstrating its potential application for competitive exclusion of pathogens. B. subtilis DG101 forms robust liquid and solid biofilms and expresses several extracellular enzymes with activity against food diet-associated macromolecules (i.e., proteins, lipids, and polysaccharides) that would be important to improve food diet digestion by the host. B. subtilis DG101 was able to grow in the presence of toxic metals (i.e., chromium, cadmium, and arsenic) and decreased their bioavailability, a feature that points to this probiotic as an interesting agent for bioremediation in cases of food and water poisoning with metals. In addition, B. subtilis DG101 was sensitive to antibiotics commonly used to treat infections in medical settings, and at the same time, it showed a potent antimicrobial effect against pathogenic bacteria and fungi. In mammalians (i.e., rats), B. subtilis DG101 colonized the GI tract, and improved the lipid and protein serum homeostasis of animals fed on the base of a normal- or a deficient-diet regime (dietary restriction). In the animal model for longevity studies, Caenorhabditis elegans, B. subtilis DG101 significantly increased the animal lifespan and prevented its age-related behavioral decay. Overall, these results demonstrate that B. subtilis DG101 is the key component of nattō with interesting probiotic properties to improve and protect human health.

Caenorhabditis elegans as a Screening Model for Probiotics with Properties against Metabolic Syndrome

“…Different Bifidobacteria and Lactobacilli strains have been demonstrated to extend nematode lifespan, mainly through modulations in the p-38 mitogen-activated protein kinases (p38-MAPK) signaling pathway [26]. For example, a recent study demonstrated that supplementation with Bacillus subtilis DG101, isolated from the traditional Japanese fermented food Nattō, extended worm lifespan by 45% and improved chemotaxis, in comparison with E. coli OP50-fed worms [27]. Similarly, supplementation with Lacticaseibacillus casei 62 and Lacticaseibacillus casei 63 increased nematode lifespan by improving the mitochondrial function, suggesting these bacterial strains as potential probiotics in sarcopenia [28].…”

Synthesis, Characterization and Potential Antimicrobial Activity of Selenium Nanoparticles Stabilized with Cetyltrimethylammonium Chloride

“…Petri dishes were filled out by the nutrient media prepared by the same method (Section S2, Supplementary). The surface of the nutrient media was inoculated by bacteria suspension using Drygalsky spatula [56]. Finally, the impregnated disks were placed on the inoculated nutrient media and incubated at 37 • C for 24 h. After incubation, the diameter of the growth inhibition zones was measured.…”