Downloaded from www.microbiologyresearch.org by IP: 54.70.40.11 On: Tue, 11 Dec 2018 13:49:39 Candida saraburiensis sp. nov. and Candida prachuapensis sp. nov., xylose-utilizing yeast species isolated in Thailand Sukanya Nitiyon, 1 Chanita Boonmak, 1,2 Somjit Am-In, 3 Sasitorn Jindamorakot, 3 Hiroko Kawasaki, 2 Wichien Yongmanitchai 1 and Savitree Limtong 1 Correspondence Savitree Limtong fscistl@ku.ac.th 1 Department of Microbiology, Faculty of Science, Kasetsart University, Bangkok, Thailand 2 Department of Biotechnology, NITE Biological Resource Center, National Institute of Technological and Evaluation, Chiba, Japan 3 Bioresources Technology Unit, National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathumthani, Thailand Four strains of two novel xylose-utilizing yeast species were obtained from samples collected in Thailand from decaying corncobs (strains KU-Xs13 T and KU-Xs18), a decaying grass (KU-Xs20) and estuarine water from a mangrove forest (WB15 T ). On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics and sequence analysis of the D1/D2 domain of the large subunit rRNA gene, the four strains were found to represent two novel species of the genus Candida in the Candida albicans/Lodderomyces elongisporus clade. Three strains (KU-Xs13 T , KU-Xs18 and KU-Xs20) were assigned as a single novel species, which was named Candida saraburiensis sp. nov. The type strain is KU-Xs13 T (5CBS 11696 T 5NBRC 106721 T 5BCC 39601 T ). Strain WB15 T represented another novel species of the genus Candida that was named Candida prachuapensis sp. nov. The type strain is WB15 T (5CBS 11024 T 5NBRC 104881 T 5BCC 29904 T ). INTRODUCTION Lignocellulose in plant biomass is currently of interest as a substrate for the production of many microbial products such as xylitol, acetic acid and ethanol (Carvalho et al., 2002; Doran-Peterson et al., 2008; Hahn-Ha ¨gerdal et al. 2006). D-Xylose is the second most abundant sugar in the lignocellulose of plant cell walls. It is a major sugar component of xylan, which is one of the principal polysaccharide constituents of lignocellulose. Many yeast species can assimilate xylose as a sole carbon source. In addition, many species have been tested for D-xylose fermentation (Barnett et al., 2000; Kurtzman & Fell, 1998; Toivola et al., 1984). Only a few yeast species have been reported to ferment D-xylose to ethanol. These include Brettanomyces naardenensis, Candida lyxosophila, Candida intermedia, Candida shehatae, Candida tenuis, Pachysolen tannophilus, Pichia segobiensis, Scheffersomyces (Pichia) stipitis (Barnett et al., 2000; Kurtzman & Fell, 1998), Candida jeffriesii, Spathaspora passalidarum (Nguyen et al., 2006) and Spathaspora arborariae (Cadete et al., 2009). During investigations of xylose-utilizing yeasts and yeasts in mangrove forest ecosystems in Thailand, four xylose- utilizing yeast strains were found to represent two novel species of the genus Candida in the Candida albicans/ Lodderomyces elongisporus clade based on the analysis of the D1/D2 domain of the large subunit (LSU) rRNA gene sequence. In this paper, three D-xylose-fermenting strains (KU-Xs13 T , KU-Xs18 and KU-Xs20) are described as Candida saraburiensis sp. nov. and one D-xylose-assimilat- ing strain (WB15 T ), is described as Candida prachuapensis sp. nov. METHODS Yeast isolation and characterization. Xylose-utilizing yeasts were isolated from decaying agricultural residues and soil using an enrichment technique. Each sample (1 g) was added to 50 ml D- xylose-yeast nitrogen base (YNB) broth (2 % D-xylose, 0.67 % Difco yeast nitrogen base; adjusted to pH 5.5 with 1 M HCl) supplemented with 0.025 % sodium propionate and 200 mg chloramphenicol l 21 in a 250 ml Erlenmeyer flask and incubated on a rotary shaker at 25 uC for 48 h. The enrichment culture was spread on D-xylose-YNB agar and incubated at 25 uC. After incubation, yeast colonies were picked Abbreviation: LSU, large subunit. The GenBank/EMBL/DDBJ accession numbers for the sequence of the D1/D2 domain of the LSU rRNA gene of strains KU-Xs13 T and WB15 T are AB534915 and AB439258, respectively. A supplementary figure is available with the online version of this paper. International Journal of Systematic and Evolutionary Microbiology (2011), 61, 462–468 DOI 10.1099/ijs.0.023317-0 462 023317 G 2011 IUMS Printed in Great Britain