S. mutans induces developmental and morphological defects in C. elegans despite prior L. casei exposure

Imbalances between pathogenic and commensal bacteria cause microbial dysbiosis that disrupts host development. Streptococcus mutans ' virulence factors promote human oral cell colonization, leading to dysbiosis if unchecked. When grown with the probiotic Lacticaseibacillus casei , a competitive relationship ensues. Using Caenorhabditis elegans , two assays quantified the effects of these bacteria on egg production and worm growth. Worms exposed to S. mutans exhibited fewer offspring, egg defects, delayed development, and twisted pharynx and dumpy phenotypes. L. casei did not prevent these effects.