Phylogenetic Diversity Of Endophytic Yeasts From The Populus Euphratica At The Ancient Rivers Of Tarim Basin And Taxonomic Identification Of Two Novel Species

1、The aim of this study was to identify the culturable endophytic yeast recoveredfrom storage liquid of six Populus Euphratica which sited in south （The dried up,ancient Kiyik River） and south-west （The dried up, ancient Ugan River） part ofKharchugha village of Lopnur county, Xinjiang, China. Through using conventionalstreak plate method,30pure cultivable yeast strains were isolated. The phenotypicproperties, biochemical characterization,26S rDNA D1/D2region sequence analysisand phylogenetic analysis showed that30strains have been classified into2phyla:Basidomycota and Ascomycota. Among them,24strains belonged to Basidomycota（80%）, including genus of Cryptococcus, Filobasidium, Rhodotorula,Sporobolomyces, Trichosporon;6strains belonged to Ascomycota （20%）, includinggenus of Aureobasidium、Candida; Cryptococcus （15strains） was the most widelydistributed and predominant genus, occupied the majority of isolates50%;Aureobasidium （5strains） and Sporobolomyces （4strains） were the sub-dominantcommunity, occupied the majority of isolates16.7%and13.3%, respectively. Amongthem, strain P-10and ZA-3were presumed to be2potential novel species within thegenus of Cryptococcus,26S rDNA D1/D2region sequence similarities to their closelyrelated members Cryptococcus aff. Laurentii （AY953961） and Cryptococcus laurentii（GQ352524） were95%and98%，respectively and the isolate ZA-8also represents apotential novel species within the genus of Sporobolomyces and its26S rDNA D1/D2sequence similarities to the closely related members Sporobolomyces nylandii（AB279629） was98%. The result showed that the culturable endophytic yeast havesome diversity in the Populus euphratica forest was a good resources for discoveringof potential novel species, it was worth further exploitation．2、Based on morphological、phenotypic and genetic characters, the taxonomic position of an potential novel species ZA-8^Twas determined. The results were asfollows: colonies are light red,cells are oval, asexual reproduction is by budding,ascospores are not produced. Growth in the presence of0.01%actinomycetes ispositive. Able to assimilate the following carbon and nitrogen sources: L-malic acid,methyl succinic acid, L-glutamic acid, α-ketoglutarate, D-grape acid, dextrin,D-arabinose, D-fiber Tong, gentiobiose, α-D-glucose, maltose, D-mannitol, D-xylose,beta-methyl-D-glucoside, sucrose, D-trehalose, loose sugar, arbutin, the D-ribose,salicin. Analysis of the26S rDNA D1/D2region sequences and phylogenetic analysisshowed that the strains ZA-8^Tis a member of the genus Sporobolomyces and its26SrDNA D1/D2sequence similarities to the closely related members Sporobolomycesnylandii （AB279629） was98%. On the basis of phenotypic properties andphylogenetic inference, strain ZA-8^Trepresents a novel species of the genusSporobolomyces, for which the name Sporobolomyces tograknsis is proposed. TheGenebank accession number is HQ234294.3、Strain KTH-63^Twas characterized using a polyphasic approach. The resultswere as follows: colonies are yellow,cells are Gram-staining-positive, non-motile,non-spore-forming, strictly aerobic rods. Growth temperature range for occursbetween10and40℃（the optimum temperature for growth is30-37℃）; The pHrange for growth is5.5-9.0（the optimum pH for growth is6.5-7.5）; Growth occurs inthe presence of0-20%（w/v） NaCl（the optimum NaCl concentration for growth is0-3%）. Strain KTH-63^Tis positive for catalase and oxidase activities, assimilation ofD-glucose, D-maltose, D-saccharose, D-saccharose, D-fructose. Analysis of the16SrRNA gene sequences of strain KTH-63^Trevealed that it is a member of the familyStaphylococcaceae. Macrococcus brunensis CCM4811^Twas the nearest relative ofthe strain KTH-63^Twith92.49%16S rRNA gene sequence similarity, The G+Ccontent of the genomic DNA of the Strain KTH-63^Twas34.1%。The major fatty acidswere anteiso-C_15:0，iso-C_16:0and iso-C_14:0. The predominant isoprenoid quinone wasMK-6. On the basis of phenotypic properties and phylogenetic inference, strain KTH-63^T represents a novel genus and a novel species of the familyStaphylococcaceae, for which the name Tarimoccocus tograknsis is proposed. Thetype strain is KTH-63^T（=CCTCC AB2011010^T=NRRL B-59557^T）.