The genera Actinomyces and mycobacterium show significant observation of gram positive bacteria because they test positive and give a violet or purple color under microscope when the undergo gram staining which is which uses crystal violet due. They are able to retain the violet color due to their posses of thick peptidoglylcan cell wall.
Actinomyces spp. Of the general actinomyces play an important role in soil ecology, and some species are human pathogens that cause diseases.
Mycobacterium genera example is bacilli which is covered with a mycolic acid coat. This waxy coat protects the bacteria from antibiotics, prevents them from destruction and hinder the penetration by Gram stain reagents. They cause different infectious diseases in humans.
Selective permeable means it selects what goes out and comes into the cell. If the cell membrane wasnt selective then things could enter the cell and destroy it.
