| Microbial ecology, the basic subject considering the interaction betweenmicroorganism and environment, could reflect the communication on substance,energy, or information between microbial community and circumstance, whichilluminate the balance of the ecosystem. Hot springs are formed by geothermal energyheating the underground water. The specific geological property and environmentalfactors make the hot springs become some distinctive ecosystems on our planet.Research on the microbial community structures of these ecosystems as well asnumerous microorganism resources would help us understand the balance mechanismof the hot springs special ecosystems and microorganism evolution mechanism. Alsoit may provide more opportunities for exploring and utilizing novel thermophilicmicroorganisms.In this study, the microbial community structure of three Changbai Mountain HotSprings (83oC,74oC,53oC respectively) were analysed by16S rRNA gene librarysequencing and terminal restriction fragment length polymorphism (T-RFLP).47bacterial16S rRNA sequences were determined in the phylogenetic tree, which can beclassified into7groups,17genus and some unassigned bacteria. The speciescomposition, population density, and relative abundance analysis of three hot springsmicrobial community structure indicated that Thermotogae, Thermus, Clostridium,Gallionellaceae, Aquificales and Pseudomonas existed in three hot springs. Wespeculated that they were the endogenous populations in three hot springs. On theother hand, microbial community distribution were different among three hot springs.The oldest Thermotogae and Aquificales in the community structure in twohigh-temperature hotsprings in the dominant flora. And Sphingobacteriia appears only in the samples of the two high-temperature hotsprings. The74oC hot spring in themost abundant microbial community diversity and evenness better. The dominant taxain these three samples indicated that the structure of74oC hot spring exhibit morediversity but most bacteria are mesophilic bacteria compare to83oC. The differenceevolution of groups is cased by temperature when the other factors are similar. Toverify the phylogenitic relationships between phylotyes in74oC and83oC samples, theaverage taxonomic distinctness were also take into account. Three samples of thesource environment close to the hotsprings springs chemical composition similar，sowe believe that the three hotsprings temperature differences lead to the bacterialecological structural differences only selection pressure. Through the analysis of threesamples of the metabolic type, three environments are rich autotrophic bacteria，hightemperature hotsprings in the light energy is dominant autotrophic bacteria.Speculated that this related to the physical and chemical factors of the ChangbaiMountain Hotsprings.On the Basis of16S rRNA sequence similarity, the thermophilic anaerobicCBS-ZTwhich was isolated from Changbai Mountain was shown to belong toFirmicutes, being most closely related to Caldicellulosiruptor saccharolyticus DSM8903(97%). The optimum temperature and pH of CBS-ZTwas74oC and7.8withcellulose as a carbon source, moreover, CBS-ZTwas capable of producing hydrogen.The fatty acid of CBS-ZTincluded C16:0(34.2%)，iso-C16:0(18%), C18:0(12.8%)，andiso-C17:0(11.1%). The DNA G+C content of CBS-ZTwas36.8%. Based on these data,CBS-ZTrepresents a novel species, meanwhile, it was a promising bacteria which canbe used to produce hydrogen and degradate cellulose.According to the16S rRNA sequence similarity, CBS28was shown to be themember of the Bacillus, with high similarity (>97%) to the Geobacillusstearothermophilus. Optimal growth of CBS28occurs at65oC and pH8.0. It can alsosurvive at80oC or in strong alkaline and acidic conditions. On the basis of thephysiological and biochemical characteristics, the extracellular enzymes of CBS28displayed activity of amylase, esterase and so on, which make it good candidate for ne w genes applied in food industry, medicine and envir onmental protecti on. |
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