Firmicutes (Bacillota)

Firmicutes (recently renamed Bacillota) is a massive phylum of bacteria, most of which possess a Gram-positive cell wall structure and many of which are capable of producing endospores for survival in harsh conditions (NCBI Taxonomy). In humans, Firmicutes represent one of the two dominant phyla in the gut microbiota, alongside Bacteroidetes, where they play essential roles in fermenting dietary fibers into short-chain fatty acids like butyrate, which serves as a primary energy source for colonocytes (NIH - Human Microbiome Project). While the phylum includes beneficial commensals like Lactobacillus, it also encompasses significant human pathogens such as Staphylococcus aureus, Streptococcus pneumoniae, and Clostridioides difficile. Because Firmicutes is a high-level taxonomic rank rather than a specific protein or receptor, it is not considered a discrete therapeutic target in drug discovery. Instead, pharmacological interventions target specific molecular components (e.g., penicillin-binding proteins) within individual pathogenic species or seek to modulate the overall phylum abundance through diet, probiotics, or fecal microbiota transplantation to treat metabolic and inflammatory disorders (PubMed, PMC4264336).

Other names

BacillotaGram-positive bacteria (Firmicutes)Endospore-forming bacteria

Drugs do not target the phylum as a whole; however, antibiotics targeting members of this phylum typically act by inhibiting peptidoglycan cell wall synthesis, protein synthesis (ribosomal inhibition), or DNA replication within specific pathogenic species.