Practice question

Low G+C Gram-positive bacteria belong to phylum Firmicutes recently renamed Bacillota, distinguished by genomic guanine-cytosine content of approximately 30 to 50 percent, lower than actinobacterial counterparts. This composition influences codon usage, thermal stability, and phylogenetic clustering via 16S rRNA secondary structure signatures. Monoderm envelope contains thick peptidoglycan with lysine-type crosslinks and teichoic acids providing structural integrity. Genera include Bacillus, Clostridium, Enterococcus, Lactobacillus, and Staphylococcus, many forming resilient endospores for survival. They dominate mammalian gut microbiota and constitute major fermentative and pathogenic lineage.