Isolation And Characterization Of Bacterio-phages From Tengchong Rehai, Yunnan, China.

Thermus strains are non-spore-forming, ancient thermophilic bacteria which belong to bacteria domain, and have been regarded as models to study the mechanism of thermostability of thermophiles. The growth optimal temperature of Thermus is between 70℃to 72℃and the optimal pH value for growth is between 7.5 to 7.8. Thermus belong to Deinococcus-Thermus, Deinococci, Thermales. Thermus strains distribute widely in hot springs all over the world and Thermus aquaticus is regarded as the model strain of genus Thermus. To date, the genomes of Thermus thermophilus HB27, Thermus thermophilus HB8 and Thermus aquaticus Y51MC23 have been sequenced. Nowadays, Thermus are the hotspots in the researches of thermophilic bacteria, and their bacteriophages begin to obtained more attention. Four groups of Thermus bacteriophages including Siphoviridae, Myoviridae, Inoviridae, Tectiviridae have been isolated and characterized.In this research, more than 30 Thermus strains were isolated from Tengchong rehai hot springs. And the characterization of four Thermus stains named TC0805, TC0810, TC0816 were further studied. TC0805, TC0810, TC0816 are similar in morphology, no pili and flagella was observed. They were aerobic, with optimal growth temperature and pH value are 70℃and 7.5, respectively. Phylogenetic analysis demonstrated that TC0805 and TC0810 were closed to Thermus rehai, they belonged to the same branch. TC0816 formed independent branch from other Thermus strains. Using the program of BLAST in NCBI, we found that the highest homology of TC0816 and the other known Thermus strains was 96%. TC0816 might be a novel species of Thermus. These result shown the diversity of Thermus in Tengchong rehai hot springs.Double-layer plate and TEM were used to investigate the Thermus bacteriophages in Tengchong rehai hot springs, more than 30 bacteriophages had been isolated and three bacteriophages infecting the Thermus. sp TC0816, TC0805, TC0810 were futher studied. They were denoted as TSP4 (Tengchong Themus siphoviridae bacteriophage 4), TSP10 (Tengchong Themus siphoviridae bacteriophage 10) and TIP5 (Tengchong Themus inoviridae bacteriophage 5), respectively. They were further characterized by morphology, genomic DNA size, phage production temperature, phage production pH value, organic solvent sensitivity and protein composition. The characterization of the three phages suggested that they were novel bacteriophages isolated from Tengchong rehai hot springs. This is the first time Thermus phages to be isolated and characterized in China.Study the diversity and distribution of Thermus and their phages could obtain novel phage resources and new functional genes, it also might help us to understand the thermostability mechanism in thermophiles and deserved for further study.