Characterization of Marine Yeasts isolated from different Substrates Collected in Calatagan, Batangas

Abstract

Marine yeasts can be isolated from various substrata. Their potential industrial application merits a thorough study of these microorganisms. Thus, our research study aimed to isolate and characterize marine yeasts from several substrata collected from Calatagan, Batangas. Marine yeasts were isolated using enrichment culture of seawater, marine sediments, and living and decaying seagrasses and seaweeds on Glucose-Yeast Extract-Peptone broth (GYPS) supplemented with 33 g/L marine salts. Following incubation at room temperature, a total of 13 yeast strains were isolated. Most of the marine yeasts were obtained from either living or decaying seagrasses. Growth on GYP Broth with and without salt showed that six out of the 13 isolates were able to grow in the presence or absence of marine salts. Characterization of the isolated marine yeasts was done using the conventional morphological and biochemical methods and modern molecular techniques. All marine yeasts have cream-colored, circular and convex colonies with entire margin. The cells were spherical with a size range of 2.5 – 12.5 μm. They utilized galactose, maltose, sucrose, trehalose, xylose, sorbitol, N-acetyl-glucosamine and 2-keto-gluconate. Only one isolate (PCL08-LG04) utilized glycerol, arabinose, cellobiose, and raffinose. Comparison of the API 20C Aux profiles with the API database indicated that the isolated marine yeasts have affinity to the genus Candida. Gene sequence analysis of their ITS 1 and 2 regions of nuclear rDNA identified the isolates as Candida tropicalis and Pichia carribica.