You have to isolate normaly on starch nitrate agar and follow the ISP protocols for actinomycetes identification. You should read from papers and ISP first.

By using the normal growth conditions, you can only grow those 'culturable' strains. The best media are ISP media. Depending on what kinds secondary metabolites you are looking, you can extract them with organic solvents and run assays such as antibacterial assay. Or you can put them on HPLC and collect fractions that have signature absorbance. For unculturable strains, the only think you could try is extracting DNA from the mixed samples and do a genomic mining. Then you could express the gene clusters you are interested heterologously and test production.

you can used ISP Media. GC-MS can help you to looking secondary metabolite. Cromatography colom can used if you looking fractions it. 

Hi Mecyel

You see this reference1

https://www.hindawi.com/journals/btri/2014/217030/

2

https://www.sciencedirect.com/science/article/pii/S0944501313001250

3

http://www.bpj-bd.com/index.php/current-issue/category/15-volumn-18-no-2-july-2015?download=318:04-evaluation-of-antibacterial-antifunfgal-and-cytotoxic-potentials-of

4

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3815768/

5

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4170486/

6

https://www.tandfonline.com/doi/full/10.1080/13102818.2015.1086280

7

https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-695X2012000200003

8

https://link.springer.com/article/10.1007/s13205-016-0518-3

 Thank you for your answers. Appreciated! :)