Efficient ethanol production using thermotolerant yeast strains was carried out with a newly isolated yeast strain called 267. Strains were isolated with an enriched technique consisting of a blackstrap molasses medium supplemented with 40 ml/l of ethanol at 25-28°C. The results revealed that 33 strains produced ethanol at 45°C in the cassava starch hydrolysate medium, pH 4.5, which was composed of 180 g/l reducing sugar and 0.5 g/l (NH 4 ) 2 SO 4 , with a shaking speed of 120 rpm. The highest ethanol concentrations (26.2, 26.2, 23.6, and 22.5 g/l) were found from Pichia kudriavzevii strains PBB511-1, TM512-2, CPY514-1, and TG514-2, respectively. The yeast strain PBB511-1, which produced the highest ethanol yield, was selected for ethanol production in the shaking flask at 45°C. Ethanol production reached the highest level after 36 h in a medium composed of 180 g/l reducing sugar, 0.5 g/l (NH 4 ) 2 SO 4 , 0.5 g/l KH 2 PO 4 , 0.5 g/l MgSO 4 · 7 H 2 O, and 1 g/l yeast extract. It produced 37 g/l ethanol, with a productivity of 1.03 (g/l)/h and a yield of 40% of the theoretical yield. The ethanol production by batch fermentation at 45°C was performed in a 7-l jar fermenter with an agitation speed of 300 rpm and an aeration rate of 0.2 vvm throughout the fermentation. The results implied that the maximum ethanol concentration was 42.4 g/l after 48 h, at a rate of 0.88 (g/l)/h and a yield of 46% of the theoretical yield.

This study aimed to explore communities and the ethanol-fermenting ability of yeasts in fresh coconut, palmyra, and nipa palm saps. From the 90 samples of coconut, palmyra, and nipa palm saps, 204 yeast isolates were isolated and identified as 15 species in the phylum Ascomycota and a species (one strain) in Basidiomycota. Saccharomyces cerevisiae, Hanseniaspora guilliermondii, and Lachancea thermotolerans were found in the saps of all three palm species. Candida tropicalis and Pichia kudriavzevii were obtained from the coconut and palmyra palm saps, Hanseniaspora vineae, Lachancea fermentati, and Pichia manshurica were present in the coconut and nipa palm saps, whereas Torulaspora delbrueckii was found in the palmyra and nipa palm saps. The species with the highest occurrence in the saps of coconut, palmyra, and nipa palms was S. cerevisiae with 76.67%, 86.70%, and 100% frequency of occurrence, respectively. Using principal coordinates analysis for ordination, no marked difference was observed in the yeast communities from the saps of the three palm species. A total of 199 isolates were found to possess ethanol-fermentation ability when cultivated using shake flask in 160 g/L of glucose medium at 28°C for 48 h. Lachancea fermentati YSP-383, isolated from nipa palm sap, produced the highest amount of ethanol (76.74 g/L). Twenty-six isolates of Candida sanyaensis (1), C. tropicalis (1), H. guilliermondii (7), L. fermentati (8), L. thermotolerans (1), Pichia kudriavzevii (2), and S. cerevisiae (6) produced high amounts of ethanol ranging from 69.57 to Electronic supplementary material The online version of this article (

Marine yeasts can occur in a wide range of habitats, including in marine invertebrates, in which they may play important roles; however, investigation of marine yeasts in marine invertebrates is scarce. Therefore, this study aims to explore the diversity of yeasts associated with corals and zoanthids in the Gulf of Thailand. Thirty-three coral and seven zoanthid samples were collected at two sampling sites near Mu and Khram islands. Fifty yeast strains were able to be isolated from 25 of the 40 samples collected. Identification based on sequence analyses of the D1/D2 domain of the large subunit rRNA gene revealed a higher number of strains in the phylum Basidiomycota (68%) than in the phylum Ascomycota. The ascomycetous yeasts comprised nine known species from four genera (Candida, Meyerozyma, Kodamaea, and Wickerhamomyces), whereas the basidiomycetous yeasts comprised 10 known species from eight genera (Vishniacozyma, Filobasidium, Naganishia, Papiliotrema, Sterigmatomyces, Cystobasidium, Rhodotorula, and Rhodosporidiobolus) and one potentially new species. The species with the highest occurrence was Rhodotorula mucilaginosa. Using principal coordinate analysis (PCoA) ordination, no marked differences were found in the yeast communities from the two sampling sites. The estimation of the expected richness of species was higher than the actual richness of species observed.

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