Isolation Of Thermophiles And Polyphasic Identification Of A New Species Of Thermoactinomycete

The extremophiles have unique genes, phisiological characteristics and metabolites compared with common microorganisms. Extremophiles are of interest to both basic and applied biology. Many extremophiles, in particular the hyperthermophiles, lie close to the "universal ancestor" of all extant life on Earth. This exciting realization has fueled much research on these organisms in order to understand the nature of primitive life forms, how the first cells "made a living" in Earth's early days, and how early organisms set the stage for the evolution of modem life forms. Many thermophiles have been isolated around the world. In China, there are many different hot springs in which thermophiles usually live. But less thermophiles have been found.18 thermophilic strains were reported here isolated from hotsprings in Yunnan. Based on the their configurations, physiological and biochemistry features, 16S rDNA sequence,most of them belong to the genus Geobacillus and Bacillus except the strain LA5. The optimum growth temperature of 18 strains were 60-75℃. Three protease-producing strains(beloned to Geobacillus)SBll, SB31 and SC5 were studied in more detail. The protease activities were 35.6, 26.1, 26.6 U/mL respectively. Although they grew best at 60℃, their protease activities were highest at 70℃, higher than those from animals and plants.Strain LA5 was a thermoactinomyces.Its colony was cream-yellow with radial winkles. The isolate grew aerobically at temperature of 50～70℃and at pH 6～10. The aerobic mycelia wasn't be observed. Single spores were produced along the substrate hypha. The strain LA5 utilized glucose, fructose, xylose, giutin, Casin and starch but not arabinose, raffinose, rhamnose, cellobiose, Hypoxanthine, Xanthine and L-Tyrosine. The strain LA5 could grow better on the following media: LB, PDA, Czapek and Starch-Casein,but weak on Glycerol-Asparagine and Gause's Synthetic meadium.Chemotaxonomical analysis revealed the presence of meso-diaminopimelic acid, alaline and glutamic acid, indicating that the cell call chemotype belonged to the typeⅢ. Whole-cell sugars were found to be glucose, ribose, without any diagnostic sugars. The major fatty acids were iso-C17:0 (27.66%) and C16:0 (22.38%) and the predominant menaquinone were MK-7( 66.58 % )和MK-8( H2 )( 33.42 % )which were quitely different from those type strains of five genera in the family'Thermoactinomycetaceae'.DNA G+C% of strain LA5 was 56.8 mol%, close to those of Planifilum fulgidum 500275T (60.0 mol%) and Planifilum fimeticola H0165T(60.3 mol%) but much higher than those of others in the family 'Thermoactinomycetaceae'.DNA Hybridization outcome demonstrated the presence of 52.7%, 43.6% homogeneity between LA5 and Planifilum fimeticola H0165T and Planifilum fulgidum 500275T respectively.On the basis of phenotypic properties and phylogeny, strain LA5 should be placed in the genus Planifilum as a member of a novel species for which we propose the name Planifilum yunnanensis sp. nov.