Mycobacteria - General Characteristics
General characteristics of Mycobacteria:
Non-motile, non-spore-forming, aerobic, have high amounts of Guanine and Cytosine in their DNA, slow-growing, and most are weakly Gram-positive.
They have lipid-rich cell walls that are:
— Acid-fast
— Resistant to detergents and antibiotics
— Contain antigens that stimulate the host immune response.
Layers of the Cell Wall:
— Cytoplasmic membrane
— Peptidoglycan layer - tends to stain weakly Gram-positive
— Arabinogalactan layer is a branched polysaccharide macromolecule that comprises arabinose and galactose residues; it links to the peptidoglycan layer, below.
— Mycolic acids, which comprises long-chain fatty acids; these acids contribute to the low permeability of Mycobacteria cell walls.
Be aware that some authors describe an outer capsule or capsule-like material.