Bacillus subtilis

Bacillus subtilis is a Gram‑positive, endospore‑forming bacterium that inhabits soil, plant surfaces, and the gastrointestinal tract of humans and animals. In dietary‑supplement form it is used primarily as a probiotic, supplying viable spores that survive gastric acidity to colonise the intestine and exert health‑promoting effects.

• Bacillus subtilis is a living, single‑cell organism; its “chemical structure” is defined by its cellular components rather than a single molecular formula.
• The bacterium’s genome comprises ~4.2 Mbp DNA (≈4.2 × 10⁶ bp) encoding ~4 300 genes.
• The cell wall is a thick peptidoglycan layer (N‑acetyl‑muramic acid‑N‑acetyl‑glucosamine polymer cross‑linked by L‑lysine‑D‑alanine peptides) typical of Gram‑positive bacteria.
• Surface‑associated proteins (e.g., S-layer protein BslA) and the spore coat contain dipicolinic acid (C₆H₆N₂O₄) and calcium ions, conferring heat resistance.
• The bacterium secretes enzymes (e.g., Bacillus subtilisin, EC 3.4.21.62) with known amino‑acid sequences and tertiary structures (e.g., 275 kDa).
• No IUPAC name applies to the organism as a whole.

• Commercial Bacillus subtilis for supplements is typically derived from a well‑characterised, non‑pathogenic strain (e.g., ATCC 6051, DSM 10674) cultured in sterile, high‑purity fermenters using defined media (glucose, amino acids, mineral salts).
• Post‑culture, spores are harvested by centrifugation, washed, and lyophilised with cryoprotectants (e.g., trehalose) to preserve viability.
• Quality‑focused manufacturers employ GMP, validated CFU counts, and third‑party testing for contaminants (heavy metals, mycotoxins, pathogenic microbes).
• Natural sources include soil, fermented foods (e.g., natto) and the human gut; however, supplement‑grade spores are produced under controlled, aseptic fermentation to ensure strain identity, spore purity (>95 % spores), and stability across shelf life.