A mixture of postbiotics/tyndallized probiotics reduces trimethylamine (TMA) in trimethylaminuria models: Evidence from in vitro and in vivo studies

<i>L. paracasei</i> fermentation yielded 4.1 × 10¹² CFU/g lyophilized powder. <i>In vitro</i> assays involving fecal slurries supplemented with the fermentation product demonstrated a reduction in TMA levels, and the NGS analysis revealed that <i>Collinsella</i>, <i>Clostridium</i>, and <i>Streptococcus</i> were the most common bacterial genera that produced TMA. The <i>in vivo</i> study showed a significant reduction in TMAO levels in C57BL/6(FMO3^+/+) strain WT mouse models and in TMA levels in C57BL/6^-Fmo3em1Smoc (KO) mouse models. In addition, bacteria belonging to the TMA-producing genera were still present after treatment with the tested compounds, excluding their bactericidal action. The postbiotics obtained may find a useful therapeutic application both in the prevention of cardiovascular events and as valid supports to reduce TMA production in TMAU patients.