| The terrestrial hot springs were worldwide spread, mainly on the tectonically active geothermal belts. Tibet and Yunnan Province of China are rich in geothermal features which belong to the Mediterranean – Himalaya geothermal belt. Hyperthermophiles and thermophiles are the major life forms in these hot spring ecosystems, where they play an important role in conducting the biogeochemical cycling. One way to gain insight into microbial functions in terms of elemental cycling is to assess the relative abundances of organisms that make up the communities and their variability across temporal and spatial scales. Our study will contribute to 1) deep exploration and utilization of thermophilic microbial resources; 2) provide data and theory for understanding biogenic elemental cycling.Here we study the microbial community distribution patterns and temporal changes of microbial community in Tibetan and Tengchong hot springs by using integrated methods including geochemistry and microbiology. Our results are as follows:1) We compared the microbial community composition in moderate-low temperature and circumneutral-alkaline hot springs between Tibet and Tengchong. It turns out the distribution patterns of microbial community are controlled by temperature: moderate temperature favored bacterial phylum Aquificae(mainly Hydrogenobacter), whereas low temperature favored Chloroflexi. Besides microbial community, temperature also controls the relative abundance of microbial lineages, for example, the relative abundance of Aquificae was correlated positively with temperature, but the abundances of Deinococcus-Thermus, Cyanobacteria and Chloroflexi were negatively correlated with temperature.2) We studied microbial community composition in moderate-high temperature and/or acidic hot springs in Tengchong and found that the microbial community distribution pattern was controlled by p H, temperature, physico-chemical parameters and mineralogy. Specifically, the Aquificae genus Hydrogenobacter or crenarchaeol orders Thermoproteales and Desulfurococcales occupied the springs with moderate-high temperature, circumneutral-alkaline p H, high concentrations of Na, K and Cl and high concentrations of silica. Tengchong Rehai geothermal field harbored some acidic springs and had elevated concentrations of SO42- and Fe2+. The dominant phyla within these acidic springs depended on temperature. High-temperature and acidic springs favored the crenarchaeal order Sulfolobales, whereas those with lower temperature favored the Aquificae genus Hydrogenobaculum. The higher microbial diversity and more complex taxonomic taxa in Ruidian sediments were likely due to the carbonate’s buffering effect.3) Water and sediment communities exhibited different temporal variation patterns. Water communities were largely stable across three sampling times and dominated by similar microbial lineages: Hydrogenobaculum in low-temperature acidic springs, Sulfolobus in high-temperature acidic springs, and Hydrogenobacter in high-temperature circumneutral to alkaline springs. Sediment communities were more diverse and responsive to changing physicochemical conditions. Most of the sediment communities in January and June were similar to those in waters. However, the August sediment community was more diverse and contained more anaerobic heterotrophs than the January and June: Desulfurella and Acidicaldus in low-temperature acidic springs, Ignisphaera and Desulfurococcus in high-temperature acidic springs, the candidate division OP1 and Fervidobacterium in alkaline springs, and Thermus and GAL35 in neutral springs. Temporal variations in physicochemical parameters including temperature, p H, and dissolved organic carbon may have triggered the observed microbial community shifts.4) We reported experimental envidence that microorganisms colonized mineral surface according to mineral’s chemistry, specifically the buffer-capacity, and the grain size of mineral. The smaller the grain size is, the more evident the selection is. |
PDF Full Text Request