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#Actinobacteria

2 public questions tagged with this topic.

Microbial Classification

High G+C Gram-positive bacteria belong to

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.

Ref: Tortora Microbiology Chapter 11 Actinobacteria high GC; Madigan Microbiology Chapter 15 Actinobacteria GC content codon usage

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Microbial Classification

Which phylum includes Mycobacterium tuberculosis?

Mycobacterium tuberculosis belongs to phylum Actinobacteria, also called Actinomycetota, defined as high G+C Gram-positive bacteria typically ranging 60 to 75 mol percent guanine-cytosine content. Members exhibit complex filamentous growth, mycolic acid-containing cell envelope conferring acid-fastness, slow growth rates, and resistance to desiccation and disinfectants. Actinobacterial 16S rRNA signatures and genome GC content cluster Mycobacterium with Streptomyces, Corynebacterium, and Nocardia. This lineage possesses unique arabinogalactan peptidoglycan and lipoarabinomannan, distinguishing it clearly from low G+C Firmicutes, Proteobacteria, and Bacteroidetes in modern bacterial systematics and clinical diagnostics.

Ref: Campbell Biology 12th ed., Chapter 27 Actinobacteria high GC Mycobacterium; Tortora Microbiology Chapter 11 Actinomycetes acid-fastness

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