Diversidade de leveduras associadas à Zoantideos marinhos (Cnidaria) em ambiente tropical

Abstract

Microorganisms are the more successful life form in the oceans, but little is known about the Fungi kingdom. In this environment, marine invertebrates are considered important microorganisms reservoirs and half the wealth of yeast that have been isolated from these invertebrates are associated with their tissues. Knowledge about that diversity is important to investigate ecological relationships and the potential that yeasts may have in biotechnology. The objective of this study was to isolate and identify cultivable yeasts associated with cnidarians belonging to Zoanthidae family. Samples of three species of soft corals, Palythoa variabilis, Palythoa caribaeorum and Zoanthus sociatus, were collected in the Ponta Verde coral reef and sandstone reef Sereia in 2014 and 2015. The samples were washed with steril sea water, macerated, diluted, plated on Wickerham's YM culture medium and incubated for up to 26 days at 22-25 ⁰C. The yeasts were stored in inclined agar GYMP covered with mineral oil maintained at a temperature of -4 °C and in microtubes containing modified YM medium at a temperature of -20 °C. The isolates had genomic DNA extracted and the region D1 / D2 LSU rDNA sequenced. A hundred thirty-nine isolates were obtained, with a prevalence of 67,62% of yeast belonging to the phylum Ascomycota within this phylum, the order Saccharomycetales was the most represented among the isolated. Basidiomycetes had the prevalence of a single order for the sandstone reef Sereia, already in Ponta Verde main orders were Microbotryomycetes and Tremellomycetes. A total of 18 of the 38 yeast species were classified as a new occurrence for the marine environment. The prevalence of the ascomycetous subphylum Saccharomycotina can be explained by being more tolerant species to environmental stress caused by the large input of organic matter derived from the urban environment that the reef gets. And can be influencing the presence of yeast with human pathogenic potential, where 84% identified isolated have this potential. Through data analysis, it is concluded that there are more species of yeast in association with marine cnidarians to be reported, including new species. As the cultivation technique is not capable of scanning all yeast species associated with soft corals during the sampling period, the sampling should be continued. Thus, the sampling should be continued in order to know the real wealth of species of cultivated yeasts in this habitat.