ACTINOMYCETES

•Actinomyctes are aerobic, gram positive bacteria that form branching filaments or hyphae and asexual spores like fungi.

•They play a major role in the mineralization of organic matter and are the primary source of most naturally synthesized antibiotics.

•Some actinomycetes develop in mycelial state reproducing by unicellular specilized spores . Eg:Actinoplanes, Streptomyces,

•They reproduce primarily by fragmentation into short rod shaped cells.Spores are not produced. Eg: Actinomyces, Nocordia, Mycobacterium.

•Cell wall has some peptidoglycan as in gram positive bacteria.

•Nocardiform actinomycetes

•These bacat teria develop as substrate mycelium that readily breaks into rod shaped or coccoid –cells.

•Some genera also form an aerial mycelium t may give rise to  conidiospores.

•The various genera of this group  resemble the genus Nocordia with respect to their morphology and cell wall composition. Hence they are collectively called nocordiforms.

•Actinomycetes with multilocular sporangia

•These organisims have hyphae that divides both transversly and longitudinally to produce clusters or packets of coccoid  or cuboid cells or spores.

•All three genera in this group have cell wall with meso diaminopimelic acid.

•Eg: Geodermatophilus, Dermatophilus, Frankia

•Actinoplanes

•The members of this group form an extensive substrate mycelium and grow  in almost all soil habits.

•The mycelium is coloured due to diffusible pigments.

•Some of the hyphae raise above the surface of the substratum  and bear a sac like sporangium at their tips. These  special hyphae are called sporangiophores.Conidiospores are formed with in the sporangium

•The spores may be motile or non motile.These bacteria vary in the arrangement and development of spores.

•Some genera have round shaped or irregular sporangia with masses of spores per sporangium .Eg: Dactylosporangium, Micromonospora

•Streptomyces and related genera

•These usually form abundant aerial mycelium

•The hyphae divide in a single plane to form chains of 5 to 50  or more non  motile conidiospores in chains at the hyphal tips.

•The spores may be smooth, hairy or spiny in texture.