Hello, you can take your soil portion and made suspension in water and wait till sediments does down and take 5ml upper liquid to liquid media for grow. Take into account not only fungi but actinomyces too and may be you will find more prospective strain. Grow cultures at thermostat at 24-25*C for one week and than use cultural liquid for checking antimicrobial activity. For antimicrobial activity checking you can take solid media melt it and fill in plate at 40*C and add your microbial cultures and mix well and keep till solidification. After take paper filter make disks by stationery hole punch and autoclave them in foil than take obtained papers fill with cultural liquid and put disks in prepared media plates with test culture. You van use different plates with different test cultures. Put the plates in optimal grow conditions for test cultures. If during the grow you will see any inhibition zone you can stat isolation of pure cultures from your soil suspension and perform the same stapes with all isolated cultures and may be you will find antimicrobial producer. Why may be? - because antimicrobial activity in mixed culture media can be inducible activity and result of microbial synergism and you will lost the activity after obtaining individual cultures. Also remember big inhibition zone in solid media not always mean high antimicrobial activity it sows activity with high diffusion ability thought agar layer, so take in to account any inhibition which may be something new. Any questions are welcome.

Good luck !

This book may help you a lot.

https://link.springer.com/referencework/10.1007%2F978-3-319-19456-1

Isabella Jessy Layan Cortes, From your question I understands that you have already isolated fungal strains from soil. For testing activity, you can grow them in appropriate culture media. Then filter the spent broth using 0.2 micron filters and use them for activity screening. Use of solvents may not be a good option as solubility of compounds varies. Once you found active isolates, you can proceed to use multiple solvents for extraction of metabolites. Ideal solvents for crude compounds extraction are ethyl acetate, chloroform etc..