Isolation and activity analysis of fungi from the rhizosphere of mangroves in Xinglin Bay, Xiamen

Abstract:

[Background] Marine microorganism is a treasure pool of natural medicine resources. Marine microorganisms produced many natural products that are different from those produced by terrestrial microorganisms. Mangroves grow in tidal flats at the junction of land and ocean, it is a special ecosystem transitioning from land to ocean, and may contains abundant microbial resources and potentially a large number of metabolites with novel structures. [Objective] This study takes sea mud and sea water from the rhizosphere of mangroves in Xinglin Bay, Xiamen as the research object, to explore the diversity of culturable marine fungi and the antibacterial and antifungal activities of the extracts, to provide strain resources for the discovery of new drug lead compounds. [Methods] After pretreatment, the samples were coated on GPY, PDA, Martin and MEA media respectively, and were cultured upside down at 28 °C. Single colonies were selected and inoculated in PDA media to yield fungal strains. The antimicrobial activity of the extracts of the isolated fungi were screened by disk diffusion test and the biodiversity of the crude extracts were evaluated by high performance liquid chromatography, and four active fungi were identified by colony morphology and rDNA ITS sequence analysis. [Results] A total of 71 fungi were isolated, 49 of which showed bioactivity against Staphylococcus aureus, 6 against Candida albicans and 2 against Escherichia coli. HS5-MEA-4 and HS6-MEA-10 were identified as Aspergillus terreus, HS5-GPY-7 and HS6-GPY-15 were identified as Aspergillus aculeatus and Aspergillus templicola, respectively. [Conclusion] The activity characteristics of fungal extracts from the marine sedimentary environment of Xinglin Bay, Xiamen were preliminarily revealed, which provides resources for the subsequent biodiversity of antibacterial and antifungal secondary metabolites.