Evaluation of antagonistic activities of microbes from Vallapattanam and Pappinishery mangrove ecosystems of Kannur district in Kerala, India

Abstract

Mangrove soil habitat is biologically rich and provides a unique ecological niche to a variety of organisms. The highly productive and diverse microbial community of the mangrove ecosystems have inspired us to study the antagonistic relation among the different microbial forms in the Vallapattanam and Pappinishery mangrove soils. From these mangrove samples a total of 28 bacteria, 22 actinomycetes and 3 fungal forms were isolated. Majority of the bacterial isolates were gram positive rods. 12 actinomycetes showed antagonistic activity towards the bacteria isolated from the same soil samples, with the highest activity shown by A11 and A16 which inhibited all the native bacteria. A16, A18, A24 and C14 demonstrated significant fungicidal activity (inhibitory zones ranging from 16 mm to 39 mm) against the three native fungi, namely, Aspergillus flavus, Penicillium and Trichoderma. A17 and A24 have shown excellent antibiosis against hospital isolates of Candida albicans, C. parapsilosis, Trichophyton rubrum, T. mentagrophytes and Cryptococcus. All the three fungal forms demonstrated antibacterial activity as high as 35 mm.  These results indicate that the crude extracts of the antagonistic fungal and actinomycete forms possess promising antimicrobial properties and can be studied in details for their novel chemotherapeutic properties.