Practice question

High G+C Gram-positive bacteria correspond to phylum Actinobacteria or Actinomycetota, defined by genomic GC content exceeding 55 percent up to 75 percent, correlating with codon bias, thermal stability, and distinct 16S rRNA secondary structure signatures. Their Gram-positive cell walls often contain meso-diaminopimelic acid, arabinogalactan, and mycolic acids in mycobacteria, exhibiting branching filamentous growth and complex developmental cycles. Representative genera include Mycobacterium, Streptomyces, Corynebacterium, and Bifidobacterium. This high GC trait reflects deep phylogenetic split from low G+C Firmicutes recognized through molecular systematics.