Formed inside of cell, contains calcium dipicolinate. Resistant to heat, drying, acids, radiation. Some actinomycetes produce conidia which are asexual spores either formed from hyphae breaking into pieces or are borne on specialized fruiting bodies. Bergey's Manual of Systematic Bacteriology is official classification system. More recent work on genetic relatedness.
Whole mass is mycelium.
Other major cell type is yeast . Cell walls composed of cellulose, chitin, mannan, glucan 2. Taxonomy based on life cycles, reproductive structures and sexual spores. Many competing classification systems. Also called phycomycetes.