A comprehensive census of microbial diversity in hot springs of Tengchong, Yunnan Province China using 16S rRNA gene pyrosequencing

The Rehai and Ruidian geothermal fields, located in Tengchong County, Yunnan Province, China, host a variety of geochemically distinct hot springs. In this study, we report a comprehensive, cultivation-independent census of microbial communities in 37 samples collected from these geothermal fields, encompassing sites ranging in temperature from 55.1 to 93.6°C, in pH from 2.5 to 9.4, and in mineralogy from silicates in Rehai to carbonates in Ruidian. Richness was low in all samples, with 21–123 species-level OTUs detected. The bacterial phylum Aquificae or archaeal phylum Crenarchaeota were dominant in Rehai samples, yet the dominant taxa within those phyla depended on temperature, pH, and geochemistry. Rehai springs with low pH (2.5–2.6), high temperature (85.1–89.1°C), and high sulfur contents favored the crenarchaeal order Sulfolobales, whereas those with low pH (2.6–4.8) and cooler temperature (55.1–64.5°C) favored the Aquificae genus Hydrogenobaculum. Rehai springs with neutral-alkaline pH (7.2–9.4) and high temperature (>80°C) with high concentrations of silica and salt ions (Na, K, and Cl) favored the Aquificae genus Hydrogenobacter and crenarchaeal orders Desulfurococcales and Thermoproteales. Desulfurococcales and Thermoproteales became predominant in springs with pH much higher than the optimum and even the maximum pH known for these orders. Ruidian water samples harbored a single Aquificae genus Hydrogenobacter, whereas microbial communities in Ruidian sediment samples were more diverse at the phylum level and distinctly different from those in Rehai and Ruidian water samples, with a higher abundance of uncultivated lineages, close relatives of the ammonia-oxidizing archaeon “Candidatus Nitrosocaldus yellowstonii”, and candidate division O1aA90 and OP1. These differences between Ruidian sediments and Rehai samples were likely caused by temperature, pH, and sediment mineralogy. The results of this study significantly expand the current understanding of the microbiology in Tengchong hot springs and provide a basis for comparison with other geothermal systems around the world

Effect of the Mendelsohn maneuver and swallowing training in patients with senile vascular dementia complicated with dysphagia

Objective We investigated the effect of the Mendelsohn maneuver and swallowing training in patients with senile vascular dementia complicated with dysphagia. Methods We randomly classified 214 patients with senile vascular dementia and swallowing dysfunction into a control group (CG, n = 106) and observation group (OG, n = 108). Both groups underwent health education, psychological intervention, and training of the oral muscle group. The OG additionally underwent the Mendelsohn maneuver and swallowing training. The Hasegawa Dementia Scale (HDS), China Stroke Scale (CSS), and Neurobehavioral Cognitive Status Examination (NCSE) were used to evaluate dementia, neurological impairment, and cognitive dysfunction, respectively. Results The OG had a higher rate of effective therapy than the CG. After intervention, the OG showed better swallowing function than the CG. At 15 days and 1 month after intervention, the OG had higher video fluoroscopic swallowing exam scores than the CG. The OG had lower serum interleukin (IL)-1, IL-6, and tumor necrosis factor-α levels than the CG. After intervention, the OG had higher HDS and NCSE scores and lower CSS scores than the CG. Conclusions The Mendelsohn maneuver and swallowing training can improve swallowing function in patients with senile vascular dementia complicated with dysphagia and help to ameliorate the inflammatory response

Microbial diversity in two cold springs on the Qinghai-Tibetan Plateau

The microbial diversity in Wuli Area, Qinghai-Tibetan Plateau was investigated using 16S rRNA gene phylogenetic analyses. A total of 117 bacterial and 66 archaeal 16S rRNA gene clones were obtained from the Wuli cold springs. The bacterial clones could be classified into Proteobacteria, Acidobacteria, Deinococci, Sphingobacteria, Flavobacteria, Nitrospirae, Actinobacteria, Gemmatimonadetes, and unclassified-bacteria; and the archaeal clones could be classified into Crenarchaeota and Thaumarchaeota. Among the major groups, Proteobacteria and Crenarchaeota were dominant in the bacterial and archaeal 16S rRNA gene clone libraries, respectively. The clone sequences obtained in Wuli cold springs were closely related to those from cold habitats, such as snow/ice/soils on high mountains or at high latitude. Especially, the microbial community composition of Wuli Area was more similar to that in Tibetan glaciers than cold environments of other locations. The data presented in this study have implications for a better understanding of microbial diversity in cold springs on the Qinghai-Tibetan Plateau

Reduction of structural Fe(III) in nontronite by thermophilic microbial consortia enriched from hot springs in Tengchong, Yunnan Province, China

Iron redox cycling provides one of the most important energy sources supporting microorganisms in terrestrial hot springs. In order to understand microbial Fe(III) reduction processes in hot springs, Fe(III)-reducing bacterial consortia were successfully retrieved from seven acidic hot springs in Tengchong County, Yunnan Province, China (a temperature range from 40.6 degrees C to 74.7 degrees C and a pH range from 2.64 to 4.72). These Fe(III)-reducing consortia were mainly composed of sulfate reducing bacteria (SRB, including Desulfotomaculum, Thermodesulfobacterium and Desulfomicrobium) and organic matter fermenting bacteria (Thermoanaerobacterium and Thermoanaerobacter), with each consortia having specific composition depending on the physio-chemical conditions of the studied hot springs. The obtained consortia were capable of dissimilatory reduction of Fe(III) in nontronite NAu-2 (ferruginous smectite) with 20.8% to 29.8% reduction extent and initial reduction rate of 0.011-0.023 mM Fe(III)/g NAu-2/h. These extents and rates were comparable to those by mesophilic Fe-reducers in the presence of electron shuttles. Both high temperature and the possible presence of electron-shuttles in hot springs may have accounted for these observed high reduction extents and rates. Various secondary minerals formed during NAu-2 bioreduction, including Fe sulfides and oxides, silicates, and silica. In one spring, illitization and kaolinization of smectite were observed, suggesting that Fe-reducers play important roles in mineral transformation in geothermal environments

Distribution and Diversity of Aerobic Carbon Monoxide-Oxidizing Bacteria in Geothermal Springs of China, the Philippines, and the United States

Accumulating genomic evidence suggests that a variety of thermophilic bacteria contain cox operons and may be capable of aerobic carbon monoxide (CO) oxidation. However, little is known about the distribution and diversity of the cox-encoding (COXE) bacteria in natural geothermal environments. In this study, we examined coxL gene (encoding the large subunit of carbon monoxide dehydrogenase: CoxL) sequences retrieved from the sediments of 25 geothermal sites located in the Qinghai-Tibetan Plateau (QTP) and Yunnan Province (YP) of China, the Bacon-Manito Geothermal Production Field (BGPF) of the Philippines, and the Great Basin of the United States (USGB). Temperature and pH ranges of the studied hot springs were 22.1 to 90.8°C and 2.7 to 9.4, respectively. Phylogenetic analyses showed that most CoxL sequences were closely related to the classes Actinobacteria, Deinococci, Ktedonobacteria, Thermomicrobia, and Clostridia, and hot springs from different regions hosted different COXE communities. In addition, these hot springs harbored some COXE bacteria that were phylogenetically distinct from those inhabiting nongeothermal ecosystems. This study revealed no significant correlation between temperature or pH and the composition or diversity of COXE communities at the global scale. However, within a given region, temperature was correlated with the COXE bacterial community composition

Thioarsenate Formation Coupled with Anaerobic Arsenite Oxidation by a Sulfate-Reducing Bacterium Isolated from a Hot Spring

Thioarsenates are common arsenic species in sulfidic geothermal waters, yet little is known about their biogeochemical traits. In the present study, a novel sulfate-reducing bacterial strain Desulfotomaculum TC-1 was isolated from a sulfidic hot spring in Tengchong geothermal area, Yunnan Province, China. The arxA gene, encoding anaerobic arsenite oxidase, was successfully amplified from the genome of strain TC-1, indicating it has a potential ability to oxidize arsenite under anaerobic condition. In anaerobic arsenite oxidation experiments inoculated with strain TC-1, a small amount of arsenate was detected in the beginning but became undetectable over longer time. Thioarsenates (AsO4-xSx2- with x = 1–4) formed with mono-, di- and tri-thioarsenates being dominant forms. Tetrathioarsenate was only detectable at the end of the experiment. These results suggest that thermophilic microbes might be involved in the formation of thioarsenates and provide a possible explanation for the widespread distribution of thioarsenates in terrestrial geothermal environments