Assessment of antimicrobial and proteolytic activity in actinomycetes of rhizospheric soils of medicinal plants (Melissa officinalis and Heracleum candicans)

Actinomycetes count was more in rhizosphere soils associated with Heracleum candicans compared to Melissa officinalis. Sixteen different strains from both the medicinal plants were identified and tested for their antimicrobial and proteolytic activity. Strain Act-M-4 gave highest inhibition by forming 50mm of clear diametric zone against Bacillus subtilis while Act-M-2, Act-M-6 and Act-M-8 did not showed any activity. However, strains Act-M-1 and Act-M-8 exhibited more potential in imparting antagonistic effect whereas from H. candicans, strain Act-H-1 showed greater antagonistic action towards Xanthomonas sp. (45mm). Antifungal activity was more in Act-M-3 and Act-M-5 towards Pythium sp. and Phytophthora sp. whereas strains of H. candicans exhibited inhibition within range of 9–34mm as a clear diametric zone. Strains from both the plants however, could not show the antifungal effect against Aspergillus sp. and Trichoderma sp.