Axenic culture of amoebae was achieved through selection of mutants capable of axenic growth. This is very similar to how viruses can not grow in axenic culture. This work was important in the development of axenic culture methods. Axenic cultures are usually checked routinely to ensure that they remain axenic. Axenic cultures of microorganisms are typically prepared by subculture of an existing mixed culture. Selection of those cultures consisting solely of the desired organism produces the axenic culture. Therefore, axenic cultures of trichomycetes are highly valuable for obtaining pure DNA samples.