Diversidade e bioprospecção de fungos associados às macroalgas antárticas Monostroma hariotti Gain e Porphyra endiviifolia (A. Gepp & E.S Gepp) Y.M. Chamberlain

The production of bioactive metabolites marine fungi have been of great interest by different research groups because the oceans cover more than 70% of the surface and form a relatively unexplored in relation to the diversity chemical and biological of microbial communities. Studies on fungi in Antarctic seaweeds are scarce and many species algicolous are endemic and/or adapted to this region may constitute an attractive source of new species and metabolites of biotechnological interest. The genus Porphyra C. Agardh and Monostroma Thuret include species of great economic importance, used in the food industry, cosmetics and pharmaceuticals in various countries. In this context, the objective of this study was to understand the diversity of algicolous fungi from Monostroma hariotti Gain and Porphyra endiviifolia (A. Gepp & ES Gepp) YM Chamberlain along a latitudinal gradient in Antarctic islands and evaluate the potential of these fungi for the production of metabolites with biological activity. The algae were collected in the Islands Elephant, King George and Deception. For isolation of fungi were collected fragments of 390 specimens of algae. The samples were obtained on substrates located in the rocky intertidal region. To isolate the fungi used were fragments of the stems of the seaweed, which were inoculated onto petri dishes containing Marine Agar. In all 278 isolates were obtained from fungi, of which, 149 filamentous fungi and yeasts 129. The isolates were grouped into morphospecies from the morphological features and later confirmed by the technique of molecular microsatellite GTG'5 using primer. One representative from each morphospecies was identified by sequencing ITS regions and domains D1/D2 rRNA gene for yeasts and filamentous respectively. The species identified belong to the genera Antarctomyces, Aspergillus, Cadophora, Candida, Cystofilobasidium, Cryptococcus, Geomyces, Guehomyces, Meyerozyma, Metschnikowia, Oidiodendron, Penicillium, Rhodotorula and Verticillium. The diversity studies indicated that the composition of the fungal seaweeds are somewhat similar, and also that the fungal species and have low specificity to the host. All fungi obtained were cultured in marine agar to obtain the crude extracts, which were evaluated for antimicrobial activity using target microorganisms: Escherichia coli, Staphylococcus aureus, Candida albicans, Candida krusei and Cladosporium sphaerospermum. Of the 218 extracts evaluated, eight had antimicrobial activity, six against C. krusei, one against against C. albicans and one against C. sphaerospermum. The extract of the fungus Geomyces pannorum UFMGCB 5987 had considered promising antimicrobial activity (95.2%). The fungi were tested for their capacity to degrade starch, carboxymethyl cellulose, xylan, protein (casein) and ester. Seventy-one per cent of isolates had at least one type of enzyme activity, being the esterase predominant (68%), followed by amylase activity (43%), protease (38%), cellulolytic (13%) and xylanolytic (0, 16%). The present results suggest the presence of a fungal community adapted to extreme conditions of Antarctica, which may play a significant ecological role in the decomposition of organic matter and nutrient cycling, in addition, some of these fungi may represent a promising source of bioactive metabolites of biotechnological interest.