Streptococcus salivarius

Key Enzymes and Functional Features#

Salivaricin A and B—Lanthibiotic bacteriocins (BLIS: bacteriocin-like inhibitory substances) that inhibit Streptococcus pyogenes, Streptococcus pneumoniae, and Streptococcus mutans. The K12 strain produces salivaricin A2 and B; the M18 strain targets cariogenic bacteria.

Urease—Some strains express urease that hydrolyzes urea to Ammonia, raising local pH. In the oral cavity this may protect against acid-mediated caries; in the gut this activity can contribute to ammonia production relevant to hepatic encephalopathy.

EPS production—Produces fructans (levan, inulin-type fructooligosaccharides) that serve as prebiotics for other commensals.

Ecological Role#

In the oral cavity, S. salivarius is a pioneer colonizer that establishes competitive exclusion against pathogenic streptococci. Its bacteriocin production creates a protective zone on the tongue and pharyngeal surfaces that reduces Group A streptococcal pharyngitis and halitosis.

In the gut, S. salivarius detection carries different significance depending on context. In healthy adults, it represents normal oral-gut transit at low abundance.

In preterm neonates, enrichment of S. salivarius (along with Rothia mucilaginosa) was detected in the Gut Microbiome before NEC onset, suggesting oral-origin organisms as early warning biomarkers for Necrotizing Enterocolitis.^{[1]Liu 2022 — Gut microbiota and SCFAs as early predictive biomarkers for neonatal NEC (pilot)Xiao-Chen Liu, Ting-Ting Du, Xiong Gao et al. · 2022Open reference 1 ↓}

In Fibromyalgia, S. salivarius was among 19 differentially abundant zOTUs in a multi-omics diagnostic signature.^{[2]Duran-Gonzalez 2025 — Multi-Omics Diagnosis of FibromyalgiaDuran-Gonzalez et al. · 2025Open reference 2 ↓} In Chronic Kidney Disease, sucroferric oxyhydroxide (iron phosphate binder) notably enriches S. salivarius, suggesting iron tolerance enables expansion under high-iron conditions.