Actinomycetes are usually having hard colonies on plate and round clumps in broth. long incubation may result in formation of powder on colonies. microscopic analysis gives chains...

but still suggestions by others working on actinos are expected...

Thanks Arvind and Benjamin for suggestions. However, colony characteristics and microscopic observation are often confusing as cell morphology seem to vary from unicellular long rods to rods in chains, some times clumping cells etc. 16s rDNA sequence may be better to go about but I wanted a quick way to separate actino from usual microbial isolates before going for 16s sequencing.

None of our cultures seems to be showing agarase activitty, but I will recheck it more carefully. Thanks.

For those who are interested in actinomycetes, our research over the past few months indicate that the colonies of actinomycetes are generally but not essentially, hard with filaments partly embedded in the agar medium on the plate. Cells have filamentous morphology with a characteristic branching pattern. Towards end of the active growth, the surface of the plate is covered with spores and a variety of attractive pigments.

Dubey Ji, I think you will be doing 16S and some sequencing also... its a good method.

Based on cultural characterization and Microscopic observation, one can say, the isolates belonging to actinomycetes group. Walksman classify the streptomyces based on spores and pigments. But, this was classical method. lot of isolates from Micromonospora, Actinoplanes, Salinispora, Some species from Nocardia, Actinomadura doesn't produce areial mycelia, it look like bacterial colony. it is not so hard. but we can identify based on spores and colony colour. But only 16S rRNA sequencing confirms the isolate at genus level.