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Wan-Norafikah O, Hasani NAH, Nabila AB, Najibah I, Nurjuani AHH, Masliana M, Aliah-Diyanah S, Alia-Yasmin Z, Yasmin-Zafirah I, Farah-Farhani A, Azahari AH, Faiqah-Nadhirah M, Nurul-Azira MS. Profiling Insecticide Susceptibility of Aedes Albopictus From Hot Springs in Selangor, Malaysia. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2023; 39:183-191. [PMID: 37796735 DOI: 10.2987/23-7125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
The present study establishes insecticide susceptibility profiles of Aedes albopictus adult populations from 4 hot springs in Selangor, Malaysia, against 7 pyrethroids through an adult mosquito susceptibility bioassay. All Ae. albopictus populations were subjected to a 1-h exposure to each pyrethroid following the World Health Organization. The mortalities were recorded at 60 min of exposure to bifenthrin, 30 min for other pyrethroids, and 24 h posttreatment for all pyrethroids. Complete mortalities were observed upon exposures to the pyrethroids under 60 min and at 24 h posttreatment, excluding permethrin 0.25%, alpha-cypermethrin 0.05%, and bifenthrin 0.2%. These findings indicated that permethrin, deltamethrin, lambda-cyhalothrin, cyfluthrin, and etofenprox possess the recommended pyrethroid adulticide active ingredients that could be applied in vector control programs at these hot springs in the future. Nevertheless, the application of pyrethroids should be carefully monitored in rotation with other insecticide classes, including organophosphates and carbamates to avoid the development of insecticide resistance among mosquito vectors towards all insecticides. Although there were no reported cases of Aedes-borne pathogens at these hot springs to date, the current study results could still assist the Malaysian health authorities in determining approaches to control Aedes populations in these hot springs, if required in the future.
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Saini N, Aamir M, Singh VK, Deepak B, Mona S. Unveiling the microbial diversity and functional dynamics of Shiv Kund, Sohna hot spring, India through a shotgun metagenomics approach. Arch Microbiol 2023; 205:323. [PMID: 37651004 DOI: 10.1007/s00203-023-03664-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 08/07/2023] [Accepted: 08/18/2023] [Indexed: 09/01/2023]
Abstract
In this research, we examined the microbial diversity in Sohna hot spring, Haryana, India using shotgun metagenome sequencing based on the Illumina Hiseq 4000 sequencing technology. The raw sequence data from metagenomic paired-end libraries were analysed for taxonomic classification, diversity, and functional annotation using MG-RAST online server. The results showed the presence of total of 57 phyla, 931 genera, and 2068 species, predominantly occupied by Moraxellaceae (Gammaproteobacteria). However, at the species level, we reported the presence of some representative pathogenic taxa, such as Acinetobacter baumannii and Moraxella osloensis. The functional annotation predicted at various levels based on SEED-based subsystem, KEGG ortholog identity (KO), Cluster of Orthologous Groups (COGs) database identified the predominance of genes associated with primary and secondary metabolism along with a crucial role in environmental and genetic signals, cellular communication, and cell signalling. Comparative Genome Analysis (CGA) using The Pathosystem Resource Integration Centre (PATRIC) tool based on genome annotation and assembly of the metagenomic libraries for representative taxon Acinetobacter baumannii (NCBI tax id:470) characterized the reads with a unique genome identifier of 470.20380 (A. baumannii DDLJ4) which is evolutionary closer to A. baumannii ATCC 470.17978 400667.7. In addition, the CARD database results about the presence of potential AMR pathotypes and the prevalence of adeABC, adeIJK, abeM gene-specific clusters that function as multidrug efflux pumps. Overall, the results provided a comprehensive insight into virulence and anti-microbial resistance mechanism and could be useful for developing potential drug targets against the possible AMR pathotypes.
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Soy S, Lakra U, Prakash P, Suravajhala P, Nigam VK, Sharma SR, Bayal N. Exploring microbial diversity in hot springs of Surajkund, India through 16S rRNA analysis and thermozyme characterization from endogenous isolates. Sci Rep 2023; 13:14221. [PMID: 37648773 PMCID: PMC10469164 DOI: 10.1038/s41598-023-41515-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 08/28/2023] [Indexed: 09/01/2023] Open
Abstract
Hot springs are a valuable source of biologically significant chemicals due to their high microbial diversity. To investigate the possibilities for industrial uses of these bacteria, researchers collected water and sediment samples from variety of hot springs. Our investigation employed both culture-dependent and culture-independent techniques, including 16S-based marker gene analysis of the microbiota from the hot springs of Surajkund, Jharkhand. In addition, we cultivated thermophilic isolates and screened for their ability to produce amylase, xylanase, and cellulase. After the optimized production of amylase the enzyme was partially purified and characterized using UPLC, DLS-ZP, and TGA. The retention time for the amylase was observed to be around 0.5 min. We confirmed the stability of the amylase at higher temperatures through observation of a steady thermo gravimetric profile at 400 °C. One of the thermophilic isolates obtained from the kund, demonstrated the potential to degrade lignocellulosic agricultural waste.
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Wang J, Chen Z, Chen X, Yang Y, Gan W, Wang F. Impact of Bad Ragaz ring in hot spring water on knee osteoarthritis: A prospective observational study. Medicine (Baltimore) 2023; 102:e34457. [PMID: 37565912 PMCID: PMC10419570 DOI: 10.1097/md.0000000000034457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 07/03/2023] [Indexed: 08/12/2023] Open
Abstract
To evaluate the impact of the Bad Ragaz ring method (BRRM) in hot spring water for knee osteoarthritis (KOA), this prospective study enrolled KOA patients treated at the hospital between March 2020 and December 2020. The primary outcome was the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index score. A total of 60 patients were included, with 30 participants in the BRRM group and 30 patients in the non-BRRM group, respectively. The mean age was 56.4 ± 10.2 years (13 females), and the duration of disease was 5.0 ± 2.2 years in the BRRM group. The mean age was 56.0 ± 11.3 years (14 females), and the disease duration was 4.7 ± 2.1 years in the non-BRRM group. There were no differences between the 2 groups in the pain, stiffness, and function scores of the WOMAC (all P > .05) before treatment. The pre post difference in total WOMAC scores (56.57 ± 12.45 vs 36.81 ± 13.51, Cohen d = 1.52, P < .01) between the 2 groups was statistically significant. Compared with the non-BRRM group, the BRRM group showed lower scores for pain (6.5 ± 1.5 vs 8.1 ± 2.9, Cohen d = -0.69, P = .01), stiffness (2.7 ± 1.0 vs 5.0 ± 1.2, Cohen d = -1.93, P < .01), and function (14.8 ± 6.6 vs 26.7 ± 7.5, Cohen d = -1.68, P < .01) after treatment. In conclusion, the BRRM might improve the pain and function of patients with KOA.
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Kataoka T, Habu H, Tanaka A, Naoe S, Murakami K, Fujimoto Y, Yukimine R, Takao S, Mitsunobu F, Yorifuji T, Yamaoka K. Association between Radon Hot Spring Bathing and Health Conditions: A Cross-Sectional Study in Misasa, Japan. ACTA MEDICA OKAYAMA 2023; 77:387-394. [PMID: 37635139 DOI: 10.18926/amo/65749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 08/29/2023]
Abstract
No epidemiological studies have examined the health effects of daily bathing in radon hot springs. In this cross-sectional study, we investigated the associations between radon hot spring bathing and health conditions. The target population was 5,250 adults ≥ 20 years old in the town of Misasa, Japan. We collected information about the participants' bathing habits and alleviation of a variety of disease symptoms, and their self-rated health (SRH). Unadjusted and adjusted odds ratios (ORs) and 95% confidence intervals (CI) were calculated. In both the adjusted and unadjusted models of hypertension, significant associations between the > 1×/week hot spring bathing and the alleviation of hypertension symptoms were observed compared to the group whose hot spring bathing was <1×/week: adjusted model, OR 5.40 (95%CI: 1.98-14.74); unadjusted model, 3.67 (1.50-8.99) and for gastroenteritis: adjusted model, 9.18 (1.15-72.96); unadjusted model, 7.62 (1.59-36.49). Compared to the no-bathing group, higher SRH was significantly associated with both bathing < 1×/week: unadjusted model, 2.27 (1.53-3.37) and > 1×/week: adjusted model, 1.91 (1.15-3.19). These findings suggest that bathing in radon hot springs is associated with higher SRH and the alleviation of hypertension and gastroenteritis.
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Wen T, Hu Z, Wang Y, Tang R. Genetic mechanism of high geotemperature in tunnels in consideration of temperature monitoring and hydrogeochemical analysis. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:85373-85389. [PMID: 37382823 DOI: 10.1007/s11356-023-28440-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 06/21/2023] [Indexed: 06/30/2023]
Abstract
During the tunnel construction, high geotemperature is a recurrent phenomenon in geothermal anomalous zones, significantly affecting both human resources and equipment involved in the process. The current study takes the Nige tunnel, the tunnel with the highest known geotemperature in China, as a case study to analyze the underlying dynamics of this phenomenon. The geotemperature within the tunnel is monitored during excavation before delving into a detailed analysis of the basic characteristics of the high geotemperatures measured. Subsequently, an investigation is conducted into the hot springs in close proximity to the Nige tunnel, which serves to reveal potential heat sources contributing to the high geotemperature. To further reveal the hydrochemical and geothermal reservoir characteristics of the area surrounding the tunnel and hot spring, a water quality test is performed. Lastly, the study situates its findings regarding the geological genesis of high geotemperature within the context of investigating heat conduction channels. Results demonstrate the coexistence of high water temperature (Water T) and rock temperature (Rock T) in the Nige tunnel, with maximum temperatures recorded as 63.4 °C and 88.8 °C, respectively. This study concludes that the source of deep circulating hot water likely stems from infiltration and combination of atmospheric precipitation and shallow water from the continental environment. Additionally, the geotemperature within tunnels primarily stems from thermal anomalous bodies in the deep crust. The performances may be used as guidance to address similar issues that arise in regions with high geotemperature.
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Khutia S, Dawn A, Seal K, Chaudhuri H, Maji C, Mukherjee S. Age-dependent potential health risk assessment due to radioactive radon-222 in the environs of highly populated Durgapur industrial zone and nearby Bakreswar hot spring, India. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2023; 45:5727-5759. [PMID: 36646974 DOI: 10.1007/s10653-023-01478-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
It is well known that exposure to a high concentration of radon-222 causes severe health effects, including cancer. The present article includes a survey on radon-222 in the water bodies of the city Durgapur [non-geothermal area] and nearby Bakreswar hot spring [geothermal province], India. The possible sources of radon from natural radionuclides and industries have been discussed in the article. Durgapur is a densely populated [~ 3680 persons/km2] industrial city with a population of 0.57 million. On the other hand, many tourists and pilgrims usually visit Bakreswar throughout the year. Age-dependent potential health risk assessments of the dwellers at Durgapur and Bakreswar due to radon exposure were performed for the first time. The present work is the first attempt to estimate the mean ingestion /and inhalation dose per annum, total effective dose [TED] per annum and the health risk assessment for cancer in adults, children and infants due to radon exposure at Durgapur and Bakreswar. In some cases, the values of TED exceed the permissible limit of 100 micro Sievert per year [µSv/y] as recommended by EUC and WHO. The radiation profile maps relating to radon concentration and associated contour maps of health risk factors [HRF] for the adults, children and infants were also prepared for the first time. Some areas were identified as high-risk zones, and the dwellers are prone to a high risk of cancer. The article also proposed several techniques to reduce radon in water and buildings. The authors also recommended banning some water sources to protect people from radon risk. This study will help scientists, policymakers, industrialists, farmers, government agencies and public health departments.
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Wang Y, Cheng H. Environmental fate and ecological impact of the potentially toxic elements from the geothermal springs. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2023; 45:6287-6303. [PMID: 37289258 DOI: 10.1007/s10653-023-01628-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 05/18/2023] [Indexed: 06/09/2023]
Abstract
Potentially toxic elements from geothermal springs can cause significant pollution of the surrounding environment and pose potential risk to the ecosystem. The fate of potentially toxic elements in the water-soil-plant system in the Yangbajain geothermal field on the Tibetan Plateau, China was investigated to assess their impact on the eco-environment. The concentrations of Be, F, As, and Tl were highly elevated in the headwaters of the Yangbajain geothermal springs, and their concentrations in the local surface water impacted by the geothermal springs reached 8.1 μg/L (Be), 23.9 mg/L (F), 3.83 mg/L (As), and 8.4 μg/L (Tl), respectively, far exceeding the corresponding thresholds for surface and drinking water. The absence of As-Fe co-precipitation, undersaturated F-, and weak adsorption on minerals at high geothermal spring pH may be responsible for the As- and F-rich drainage, which caused pollution of local river. As concentrations in the leaves of Orinus thoroldii (Stapf ex Hemsl.) Bor were up to 42.7 μg/g (dry weight basis), which is an order of magnitude higher than the allowable limit in animal feeds. The locally farmed yaks are exposed to the excessive amount of F and As with high exposure risk through water-drinking and grass-feeding.
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Muhammad S, Haq A. Spatial distribution of radon contamination in hot springs water and its cancer and non-cancer risks in the Hunza-Nagar valley, Pakistan. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2023; 45:5829-5840. [PMID: 37160537 DOI: 10.1007/s10653-023-01596-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 10/03/2022] [Indexed: 05/11/2023]
Abstract
Radon (222Rn) is a ubiquitous radioactive gas and could threaten human life due to its potential for cancer and non-cancer risks. This study examined the measurement of 222Rn concentration and associated health risks in the hot springs of Hunza-Nagar valley. For this purpose, the hot springs water of Hunza and Nagar districts and the background sites were analyzed for 222Rn concentration using the RAD7 detector (Durridge Company, USA). The average concentrations of 222Rn were 46.1 ± 0.94, 65.3 ± 0.45, and 5.47 ± 0.25 Bq/L in the Hunza district, Nagar district, and background sites, respectively. Results showed that 222Rn concentrations of hot springs water were multifold higher than the background sites. 222Rn concentrations for hot springs water in Hunza-Nagar valley had surpassed the maximum contamination level set by the US environmental protection agency (USEPA). Humans' annual mean exposure dose rates of various age groups were calculated for the estimated lifetime cancer risk (ELCR) and non-cancer risks. The total annual mean exposure doses from 222Rn in water (EwTotal) values were (187 ± 3.80, 265 ± 1.84, and 22.2 ± 1.02 μSv/a) for infants (143 ± 2.92, 203 ± 1.40, and 17.0 ± 0.78 μSv/a) children, and (138 ± 2.80, 196 ± 1.35, and 16.4 ± 0.76 μSv/a) adults in the Hunza district, Nagar district, and background, respectively. Among the age groups of humans, infants showed a higher risk than others. Results showed that hot springs water consumption surpassed the world health organization threshold of 100 μSv/y for chronic or non-cancer and USEPA 0.1 × 10-3 for ELCR risks. The concentration of 222Rn showed a positive correlation (> 0.68) with hot springs' water temperature and pH suggesting a common origin.
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Zhang Y, Liu T, Li MM, Hua ZS, Evans P, Qu Y, Tan S, Zheng M, Lu H, Jiao JY, Lücker S, Daims H, Li WJ, Guo J. Hot spring distribution and survival mechanisms of thermophilic comammox Nitrospira. THE ISME JOURNAL 2023; 17:993-1003. [PMID: 37069235 PMCID: PMC10284858 DOI: 10.1038/s41396-023-01409-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 03/29/2023] [Accepted: 03/31/2023] [Indexed: 04/19/2023]
Abstract
The recent discovery of Nitrospira species capable of complete ammonia oxidation (comammox) in non-marine natural and engineered ecosystems under mesothermal conditions has changed our understanding of microbial nitrification. However, little is known about the occurrence of comammox bacteria or their ability to survive in moderately thermal and/or hyperthermal habitats. Here, we report the wide distribution of comammox Nitrospira in five terrestrial hot springs at temperatures ranging from 36 to 80°C and provide metagenome-assembled genomes of 11 new comammox strains. Interestingly, the identification of dissimilatory nitrate reduction to ammonium (DNRA) in thermophilic comammox Nitrospira lineages suggests that they have versatile ecological functions as both sinks and sources of ammonia, in contrast to the described mesophilic comammox lineages, which lack the DNRA pathway. Furthermore, the in situ expression of key genes associated with nitrogen metabolism, thermal adaptation, and oxidative stress confirmed their ability to survive in the studied hot springs and their contribution to nitrification in these environments. Additionally, the smaller genome size and higher GC content, less polar and more charged amino acids in usage profiles, and the expression of a large number of heat shock proteins compared to mesophilic comammox strains presumably confer tolerance to thermal stress. These novel insights into the occurrence, metabolic activity, and adaptation of comammox Nitrospira in thermal habitats further expand our understanding of the global distribution of comammox Nitrospira and have significant implications for how these unique microorganisms have evolved thermal tolerance strategies.
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Ojima S, Ohishi M. Effects of hot spring bathing on cardiac and vascular function. Hypertens Res 2023; 46:1705-1706. [PMID: 37095340 DOI: 10.1038/s41440-023-01290-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 04/05/2023] [Indexed: 04/26/2023]
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Jaiswal TP, Chakraborty S, Sharma S, Mishra A, Mishra AK, Singh SS. Prospects of a hot spring-originated novel cyanobacterium, Scytonema ambikapurensis, for wastewater treatment and exopolysaccharide-enriched biomass production. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:53424-53444. [PMID: 36856995 DOI: 10.1007/s11356-023-26032-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
The present work performs the polyphasic characterization of a novel cyanobacterial species Scytonema ambikapurensis isolated from an Indian hot spring and evaluates its wastewater bioremediation potential. While the physicochemical analyses of the wastewater indicated high load of nutrients and metals, the wastewater bioremediation experiment performed using the test cyanobacterium denoted the removal of 70 and 86% phosphate, 49 and 66% sulfate, 96 and 98% nitrate, 91 and 92% nitrite, 95 and 96% ammonia, 66 and 72% chloride, 79 and 81% zinc, 68 and 80% nickel, 81 and 90% calcium, and 80 and 90% potassium from the autoclaved and un-autoclaved wastewater, respectively, after 20 days of culturing. The kinetics study of zinc and nickel removal from wastewater revealed that the cyanobacterium employed sequential biosorption (by following pseudo-second-order kinetics model) and bioaccumulation methods to remove these two metals. The quality of the autoclaved and un-autoclaved wastewater was further improved by the cyanobacterium through reduction of hardness by 74 and 81%, respectively. In wastewater, the cyanobacterium not only enhanced its biomass, chlorophyll and carbohydrate contents, but also produced small amount of released and high capsular exopolysaccharide (EPS). The FTIR and TGA analyses of capsular EPS unraveled that it was a negatively charged sulfated biomolecule having thermostability up to 240 °C, which suggested its possible use as excellent emulsifying, viscosifying, and biosorption agent. The credibility of this EPS as biosorption agent was ascertained by evaluating its metal chelating ability. Finally, the experimental data denoting the ability of S. ambikapurensis to bioremediate wastewater and simultaneously produce EPS was statistically validated by PCA1-pollutant removal model and the PCA2-cellular constituent model, respectively. Briefly, the study discloses that the cyanobacterium has huge biotechnological and industrial importance as it bioremediates wastewater and simultaneously produces thermostable exopolysaccharide.
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Zhao J, Shakir Y, Deng Y, Zhang Y. Use of modified ichip for the cultivation of thermo-tolerant microorganisms from the hot spring. BMC Microbiol 2023; 23:56. [PMID: 36869305 PMCID: PMC9983152 DOI: 10.1186/s12866-023-02803-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 02/20/2023] [Indexed: 03/05/2023] Open
Abstract
BACKGROUND Thermostable microorganisms are extremophiles. They have a special genetic background and metabolic pathway and can produce a variety of enzymes and other active substances with special functions. Most thermo-tolerant microorganisms from environmental samples have resisted cultivation on artificial growth media. Therefore, it is of great significance to isolate more thermo-tolerant microorganisms and study their characteristics to explore the origin of life and exploit more thermo-tolerant enzymes. Tengchong hot spring in Yunnan contains a lot of thermo-tolerant microbial resources because of its perennial high temperature. The ichip method was developed by D. Nichols in 2010 and can be used to isolate so-called "uncultivable" microorganisms from different environments. Here, we describe the first application of modified ichip to isolate thermo-tolerant bacteria from hot springs. RESULTS In this study, 133 strains of bacteria belonging to 19 genera were obtained. 107 strains of bacteria in 17 genera were isolated by modified ichip, and 26 strains of bacteria in 6 genera were isolated by direct plating methods. 25 strains are previously uncultured, 20 of which can only be cultivated after being domesticated by ichip. Two strains of previously unculturable Lysobacter sp., which can withstand 85 °C, were isolated for the first time. Alkalihalobacillus, Lysobacter and Agromyces genera were first found to have 85 °C tolerance. CONCLUSION Our results indicate that the modified ichip approach can be successfully applied in a hot spring environment.
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Wang L, Xin L, Zhu Y, Fang Y, Zhu L. Associations between temperature variations and tourist arrivals: analysis based on Baidu Index of hot-spring tourism in 44 cities in China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:43641-43653. [PMID: 36670219 PMCID: PMC9857907 DOI: 10.1007/s11356-023-25404-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 01/14/2023] [Indexed: 06/17/2023]
Abstract
Hot-spring tourism refers to entertainment, health preservation, commercial conferences, and other leisure activities at hot-spring locations. This tourism often shows periodic variability, which may be due to seasonal temperature variations. However, studies on the effects of temperature variations on tourist arrivals at hot springs are limited. Therefore, this study aimed to evaluate this relationship in 31 provincial capital cities and 13 s-tier cities in China. Using the Baidu Index, we obtained data for tourist arrivals to hot springs in each city and constructed a generalised additive model to explore the associations between temperature variations and tourist arrivals. We also analysed the statistical significance of the estimated effects during different seasons to explore potential effect modification. A 1 °C increase in temperature was associated with a 1.81% (95% confidence interval (CI): 1.69-1.93) decrease in daily tourist arrivals for hot-spring tourism. Significant positive associations between the abovementioned factors were observed in summer (2.18% change, 95% CI: 1.32-3.04). The effect of temperature on the volume of tourist arrivals may last for approximately 2 months. Robustness analysis confirmed the data reliability. The results indicate that significant relationships exist between temperature variations and hot-spring tourism arrivals, which vary seasonally. This study has significant implications for travel agencies to effectively manage tourist visits to hot spring locations.
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Fagbohun IR, Akindele EO, Adedapo AM, Aliu OO. Assessment of the biological water quality and response of freshwater macroinvertebrates to thermal stress in an Afrotropical warm spring. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:47755-47768. [PMID: 36740614 DOI: 10.1007/s11356-023-25670-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 01/28/2023] [Indexed: 02/07/2023]
Abstract
Freshwater macroinvertebrates have been widely used as environmental stress indicators. However, information on their response to natural thermal stress is relatively scarce, particularly in the tropics. Using the multimetric macroinvertebrate approach, the biological water quality of the warm and cold springs of the Ikogosi Warm Spring in Nigeria was evaluated, with a view to ascertaining the response of freshwater macroinvertebrates to natural thermal stress. Macroinvertebrates and water samples were collected from the warm (stressed) and cold (less-stressed) springs, as well as the confluence stream, within the renowned Ikogosi Warm Spring of Southwest Nigeria. The less-stressed cold spring had much more dissolved oxygen than the warm spring and other thermally stressed stations but less than the warm spring and other thermally stressed stations for water temperature, electrical conductivity, total dissolved solids, Ca2+, Mg2+, and water hardness. Generally, the macroinvertebrate taxonomic richness (30 species) and EPT richness (3 species) of the Ikogosi Warm Spring indicated an impaired freshwater system. Using the multimetric macroinvertebrate index (MMI), the warm spring was of poor biological water quality while the cold spring was of good biological water quality. At the confluence of both springs, the MMI declined to poor and moderate water quality. Although the thermal stress of the Ikogosi Warm Spring is natural, the government should take the necessary steps to regulate tourist activities so that the site's naturalness is preserved and the water quality is not further degraded on account of human-induced stressors such as deforestation, waste dumping, and washing activities.
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Ngansom W, Rodphothong D, Itthipoonthanakorn T, Niyomdecha S, Dürrast H, Yongprawat M. Hydrogeological environments and radon activities of saline geothermal hot spring sites located along eastern and western coastlines of southern Thailand. JOURNAL OF CONTAMINANT HYDROLOGY 2023; 253:104105. [PMID: 36396528 DOI: 10.1016/j.jconhyd.2022.104105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/25/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
Hydrogeological settings and natural radionuclides of saline geothermal fields along the coastlines of the Gulf of Thailand and Andaman Sea in Southern Thailand are currently not fully understood. Six saline geothermal springs have been discovered in Surat Thani Province (Southern Thailand's east coast); SR2, SR3, and SR7 sites; Krabi Province (Southern Thailand's west coast); KB2, KB3, and KB4 sites. Based on total dissolved solid contents, we divided the saline geothermal springs into three categories: a) slightly saline geothermal spring had only SR7 (1828 mg/L), b) moderately saline geothermal spring consisted of SR2 (10,196 mg/L) and KB3 (3448 mg/L), and c) very saline geothermal spring comprised SR3 (11,856 mg/L), KB2 (17,014 mg/L) and KB4 (18,070 mg/L). The major ions in the saline geothermal groundwater represent decreasing trends with the distance from the coastline. Stable isotope signatures (δ18O and δ2H) relative to the VSMOW plotted in comparison with the global meteoric water line and local meteoric water line are presumably of meteoric origin and influenced by seawater/brackish water. However, the SR7 and KB3 sites indicated that the isotopic signatures were mainly recharged by rainwater. Significantly, the Na-K-Ca-Mg geothermometer can reasonably estimate the reservoir temperatures for the five saline geothermal springs to be in the range of 120 °C (KB3) to 169 °C (SR2). While the SR7, the silica-quartz geothermometer is proposed of approximately 115 °C. However, the silica-chalcedony and other cation geothermometers fail to estimate suitable reservoir temperatures. On the other hand, the radon concentrations in the saline geothermal groundwater along the Gulf of Thailand and Andaman Sea were assessed by RAD7-H2O, which varied from 18.64 ± 0.96 kBq/m3 (KB2; Andaman Sea side) to 8507.48 ± 1.06 kBq/m3 (SR7; Gulf of Thailand side). A comparison of radon activity with the saltwater intrusion showed that the saline geothermal groundwater on the Gulf of Thailand side had higher levels than that at the Andaman Sea side. The deposition of Quaternary sediments combined with significant saltwater inflow enriched with radon resulted from the decay of uranium from both non-marine and coastal deposits related to granitic mountain weathering along the Gulf of Thailand. Radon concentrations in the geothermal groundwater were highly influenced by the local geological environment and coastal sediments.
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Muzuni, Aprilyani R, Ardiansyah, Suriana, Farij M, Gultom MT. Characterization of the Type 2 L-Asparaginase Gene in Thermohalophilic Bacterial from Wawolesea Hot Springs, Southeast Sulawesi, Indonesia. Pak J Biol Sci 2023; 26:392-402. [PMID: 37902081 DOI: 10.3923/pjbs.2023.392.402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
<b>Background and Objective:</b> Type 2 L-asparaginase enzyme can be used as a cancer therapy agent and prevent acrylamide formation in food products. Enzymes produced by thermohalophilic bacteria can provide high activity at high temperatures so they are needed on an industrial scale. Hence, this study aims to determine the characteristics of the gene encoding type 2 L-asparaginase enzyme in the thermohalophilic bacterial isolate CAT3.4. <b>Materials and Methods:</b> This research is a type of exploratory research. The characteristics of the gene encoding type 2 L-asparaginase were determined using the PCR technique using the primer pairs AsnBac2-F2 (5'-CTCACGGGAATCTCCATAACTC-3') and AsnBac2-R2 (5'CAGCGATGTAACAGACAGCATC-3'). The characterization process was carried out in stages: Isolation of genomic DNA using a modified alkali-lysis method, nucleotide and protein similarity analysis using BLASTn analysis on the NCBI website, construction of a phylogenetic tree using the MEGAX program, restriction enzyme mapping and amino acid analysis using the Bioedit program. <b>Results:</b> The characterization results showed that the PCR product has a size of 1594 bp with a CDS of 1128 bp, has a similarity value of 100% with <i>Bacillus subtilis</i>, has seven restriction enzymes as molecular markers for the type 2 L-asparaginase gene at the species level: <i>Bsr</i>GI, <i>Dra</i>I, <i>Eco</i>RV, <i>Hind</i>III, <i>Hpy</i>CH4IV , <i>Ssp</i>I and <i>Tai</i>I, have dominant hydrophilic regions and are in the same subclass as <i>Bacillus subtilis</i> strain GOT9. <b>Conclusion:</b> The target gene was similar to the gene encoding type 2 L-asparaginase from <i>Bacillus subtilis</i> with a max identity of 98.85%, query coverage value of 100% and E-value of 0.
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Salvo M, Azambuya J, Baccardatz N, Moriondo A, Blanco R, Martinez M, Direnna M, Bertolini G, Gamazo P, Colina R, Alvareda E, Victoria M. One-Year Surveillance of SARS-CoV-2 and Rotavirus in Water Matrices from a Hot Spring Area. FOOD AND ENVIRONMENTAL VIROLOGY 2022; 14:401-409. [PMID: 36181654 PMCID: PMC9525940 DOI: 10.1007/s12560-022-09537-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 09/18/2022] [Indexed: 06/16/2023]
Abstract
The pandemic of Coronavirus Disease 2019 (COVID-19) caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is still impacting not only on human health but also all economic activities, especially in those related to tourism. In this study, in order to characterize the presence of SARS-CoV-2 in a hot spring park in Uruguay, swimming pools water, wastewater, and surface water from this area were analyzed by quantitative PCR. Wastewater from Salto city located next to the hydrothermal spring area was also evaluated as well as the presence of Rotavirus (RV). Overall, SARS-CoV-2 was detected in 13% (13/102) of the analyzed samples. Moreover, this virus was not detected in any of the samples from the swimming pools water and was present in 18% (3/17) of wastewater samples from the hotels area showing the same trend between the titer of SARS-CoV-2 and the number of infected people in Salto city. SARS-CoV-2 was also detected in wastewater samples (32% (11/34)) from Salto city, detecting the first positive sample when 105 persons were positive for SARS-CoV-2. Rotavirus was detected only in 10% (2/24) of the wastewater samples analyzed in months when partial lockdown measures were taken, however, this virus was detected in nearly all wastewater samples analyzed when social distancing measures and partial lockdown were relaxed. Wastewater results confirmed the advantages of using the detection and quantification of viruses in this matrix in order to evaluate the presence of these viruses in the population, highlighting the usefulness of this approach to define and apply social distancing. This study suggests that waters from swimming pools are not a source of infection for SARS-CoV-2, although more studies are needed including infectivity assays in order to confirm this statement.
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Yin Z, Ye L, Jing C. Genome-Resolved Metagenomics and Metatranscriptomics Reveal that Aquificae Dominates Arsenate Reduction in Tengchong Geothermal Springs. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:16473-16482. [PMID: 36227700 DOI: 10.1021/acs.est.2c05764] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Elevated arsenic (As) is common in geothermal springs, shaping the evolution of As metabolism genes and As transforming microbes. Herein, genome-level microbial metabolisms and As cycling strategies in Tengchong geothermal springs were demonstrated for the first time based on metagenomic and metatranscriptomic analyses. Sulfur cycling was dominated by Aquificae oxidizing thiosulfate via the sox system, fueling the respiration and carbon dioxide fixation processes. Arsenate reduction via arsC [488.63 ± 271.60 transcripts per million (TPM)] and arsenite efflux via arsB (442.98 ± 284.81 TPM) were the primary detoxification pathway, with most genes and transcripts contributed by the members in phylum Aquificae. A complete arsenotrophic cycle was also transcriptionally active as evidenced by the detection of aioA transcripts and arrA transcript reads mapped onto metagenome-assembled genomes (MAGs) affiliated with Crenarchaeota. MAGs affiliated with Aquificae had great potential of reducing arsenate via arsC and fixing nitrogen and carbon dioxide via nifDHK and reductive tricarboxylic acid (rTCA) cycle, respectively. Aquificae's arsenate reduction potential via arsC was observed for the first time at the transcriptional level. This study expands the diversity of the arsC-based arsenate-reducing community and highlights the importance of Aquificae to As biogeochemistry.
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Mahajan T, Paikaray S. Fluoride retention kinetic and equilibrium studies on layered double hydroxides under ambient conditions: Implications on pond-stream-hot spring-well water remediation. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2022; 94:e10804. [PMID: 36346371 DOI: 10.1002/wer.10804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 09/19/2022] [Accepted: 10/09/2022] [Indexed: 06/16/2023]
Abstract
Fluoride deficiency and toxicity severely affect a large population globally. Hence, a low-cost geosorbent is in demand to overcome fluorosis hazards where in situ retardation is prioritized over pilot-scale waste water treatment. This study reports the fluoride removal potential of MgFe-type layered double hydroxide (HT-LDH) and its calcined form at 500 and 800°C for their usability for treatment of polluted streams, ponds, wells, and hot spring water. Rapid uptake with >33% removal in 24 h was found by the adsorptive method, whereas the co-precipitation process removed >16 mg/L (>83%) in 1 h. The efficiency was further enhanced upon calcination at 500°C with >95% removal up to five times regeneration, unlike that at 800°C. It was demonstrated that multilayer sorption onto heterogeneous surface sites is majorly controlled by surface adsorptive and ion exchange mechanisms. Acidic pH, low aqueous F - , and temperature >25°C favored greater uptake, whereas competitive anions slightly enhanced its potential in the order N O 3 - > S O 4 2 - > P O 4 3 - in adsorptive removal. In the co-precipitation process, competing anions slightly hindered F - retention, whereas high temperature and low aqueous F - led to greater F - retention. No F-bearing solid phases were evidenced upon its retention, except lowering the HT-LDH crystallinity and rearrangement of C O 3 2 - surface functional groups. The fluoride contents of natural water were lowered drastically up to 77% in 60 min upon precipitation of HT-LDH by maintaining alkalinity and a di-/trivalent cationic ratio of 2.0. PRACTITIONER POINTS: F^- uptake is rapid on heterogeneous surface sites with multilayer sorption mechanism Greater F^- removed by coprecipitation technique compared with adsorptive pathway Acidic medium and temperature >25°C favor greater F^- retention NO_3^-+PO_l4^(3-) slightly enhanced F^- uptake by adsorption but lowered in coprecipitation Formation of LDH from natural waters lowered F^- content up to <77.
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Mei N, Postec A, Bartoli M, Vandecasteele C, Wils L, Gil L, Monnin C, Pelletier B, Erauso G, Quéméneur M. Methanobacterium alkalithermotolerans sp. nov., a novel alkaliphilic and hydrogen-utilizing methanogen isolated from an alkaline geothermal spring (La Crouen, New Caledonia). Int J Syst Evol Microbiol 2022; 72. [PMID: 36260502 DOI: 10.1099/ijsem.0.005554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023] Open
Abstract
An anaerobic, hydrogenotrophic methane-producing archaeon was isolated from an alkaline thermal spring (42 °C, pH 9.0) in New Caledonia. This methanogen, designated strain CANT, is alkaliphilic, thermotolerant, with Gram-positive staining non-motile cells. Strain CANT grows autotrophically using hydrogen exclusively as an energy source and carbon dioxide as the sole carbon source (without the requirement of yeast extract or other organic compounds). It grows at 20-45 °C (optimum, 45 °C) and pH 7.3-9.7 (optimum, pH 9.0). NaCl is not required for growth (optimum 0 %) but is tolerated up to 1.5 %. It resists novobiocin, streptomycin and vancomycin but is inhibited by ampicillin and penicillin, among other antibiotics. The genome consists of a circular chromosome (2.2 Mb) containing 2126 predicted protein-encoding genes with a G+C content of 36.4 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain CANT is a member of the genus Methanobacterium, most closely related to the alkaliphilic Methanobacterium alcaliphilum WeN4T with 98.5 % 16S rRNA gene sequence identity. The genomes of strain CANT and M. alcaliphilum DSM 3459, sequenced in this study, share 71.6 % average nucleotide identity and 14.0 % digital DNA-DNA hybridization. Therefore, phylogenetic and physiological results indicate that strain CANT represents a novel species, for which the name Methanobacterium alkalithermotolerans sp. nov. is proposed, and strain CANT (=DSM 102889T= JCM 31304T) is assigned as the type strain.
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Hakeem IJ, Zewudie GT. Antioxidant Effect and Acute Oral Toxicity of Hot Springs. COMPUTATIONAL INTELLIGENCE AND NEUROSCIENCE 2022; 2022:4200824. [PMID: 36210965 PMCID: PMC9534612 DOI: 10.1155/2022/4200824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 09/06/2022] [Indexed: 11/23/2022]
Abstract
According to the research, there are many illnesses for which therapeutic mineral hot springs are employed as an alternative. Its physicochemical characteristics have a substantial body of evidence. The in vivo antioxidant effect of Mosul's hot springs in Iraq has been investigated in the current investigation. An experimental design for toxicity, a control group, and a study group were created. In addition, in vivo antioxidant effect of the hot springs of Mosul, Iraq, has been studied by the lipid antiperoxidation method with (p < 0.05), in vitro by the free radical scavenging method (DPPH) for its complexing capacity of hot springs. In acute oral toxicity in vivo at fixed doses, looking for signs and symptoms of toxicity, there are no signs of intoxication or significant changes in the biochemical analysis (blood count). And, it was discovered that the variances are substantial. The animal was necropsied, and hematological and biochemical parameters were determined, as well as the organs' histological processing at the study's conclusion. It was found that the thermal waters from Mosul, Iraq, are medicinal mineral waters, chlorinated, sodium, and sulfated, nontoxic and have an antioxidant effect. With the help of the research's findings, it is hoped to provide scientific support for knowledge that, when made public, encourages the development of Mosul's hot springs as a safe and environmentally friendly tourist destination. With the results of this research, the parameters were presented with their mean and standard deviation statistics, promoting the ecological and sanitary tourism development of the Mosul hot springs, which will generate more significant income for the population, therefore growth in the region.
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Okazaki T, Kamio H, Yoshioka M, Ueda A, Kuramitz H, Watanabe T. U-shaped plastic optical fiber sensor for scale deposition in hot spring water. ANAL SCI 2022; 38:1549-1554. [PMID: 36152169 DOI: 10.1007/s44211-022-00189-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 09/08/2022] [Indexed: 11/26/2022]
Abstract
Fiber optic sensors for monitoring scale deposition in geothermal brine and hot spring water should be safe, easily fabricated, and readily disposable. These desired features already have been enhanced in plastic optical fibers (POFs) and U-shaped sensors for other applications. The present work reports a U-shaped POF sensor for CaCO3 scale deposition. The sensors were easily fabricated by thermally bending the bulk POF without removing the cladding. At the bend, the percentage of total internal reflection between the water and the POF surface is affected by the high refractive index of the CaCO3 deposit. The optical responses of the U-shaped sensor to CaCO3 formation were investigated in a mixture of calcium chloride dehydrate and sodium hydrogen carbonate using a white-light source and a spectroscopic detector. The sensor was responsive to CaCO3 formation on the sensor surface and was especially sensitive at small bending radii. The sensitivity was further enhanced by increasing the number of bends. Finally, the U-shaped POF sensor was applied to the monitoring of CaCO3 scale deposition in hot spring water sampled at Matsushiro, Japan.
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Prajapati M, Shah M, Soni B. A review on geothermal energy resources in India: past and the present. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:67675-67684. [PMID: 35931857 DOI: 10.1007/s11356-022-22419-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 08/02/2022] [Indexed: 06/15/2023]
Abstract
By 2040, India hopes to have completed its energy supply to fulfill the country's rising energy demands. Renewable and conventional sources must be used in an environmentally acceptable manner to achieve sustainable growth. India must enhance its use of renewable and clean energy sources, including geothermal, wind, and solar, to satisfy its growing demand. While solar and wind energy output has increased significantly, geothermal energy has yet to be fully harnessed. Among the many forms of geothermal energy found on the surface are volcanoes, fumaroles, erupting geysers, steaming fields, and hot springs. A total of about 340 geothermal springs may be found in India, spread throughout both orogenic (in the Himalayas) and non-orogenic (in the Peninsula). There were 31 places extensively evaluated, and deep drilling was performed in sixteen of them. Average temperatures range from 35.0°C to the boiling point of water in these springs. Medium (100.0-200.0°C) and low (100°C) enthalpy geothermal energy resources/systems are found in India, with the latter being the most abundant. The essential component of a geothermal system is understanding the heat source and harnessing it. Studies so far have indicated that some geothermal areas have sufficient geothermal potential for direct heat usage and power generation. If the Puga (J&K) field is explored to a depth of at least 500 m, reservoir simulation studies have shown that it might produce more than 3 MW of power. India's diverse geothermal sites and the current status of exploration for future research are discussed in the paper.
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Mefferd CC, Zhou E, Seymour CO, Bernardo NA, Srivastava S, Bengtson AJ, Jiao JY, Dong H, Li WJ, Hedlund BP. Incomplete denitrification phenotypes in diverse Thermus species from diverse geothermal spring sediments and adjacent soils in southwest China. Extremophiles 2022; 26:23. [PMID: 35802188 PMCID: PMC9270275 DOI: 10.1007/s00792-022-01272-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 06/06/2022] [Indexed: 01/22/2023]
Abstract
A few members of the bacterial genus Thermus have been shown to be incomplete denitrifiers, terminating with nitrite (NO2-) or nitrous oxide (N2O). However, the denitrification abilities of the genus as a whole remain poorly characterized. Here, we describe diverse denitrification phenotypes and genotypes of a collection of 24 strains representing ten species, all isolated from a variety of geothermal systems in China. Confirmed terminal products of nitrate reduction were nitrite or N2O, while nitric oxide (NO) was inferred as the terminal product in some strains. Most strains produced N2O; complete denitrification was not observed. Denitrification phenotypes were largely consistent with the presence of denitrification genes, and strains of the same species often had the same denitrification phenotypes and largely syntenous denitrification gene clusters. Genes for nirS and nirK coexisted in three Thermus brockianus and three Thermus oshimai genomes, which is a unique hallmark of some denitrifying Thermus strains and may be ecologically important. These results show that incomplete denitrification phenotypes are prominent, but variable, within and between Thermus species. The incomplete denitrification phenotypes described here suggest Thermus species may play important roles in consortial denitrification in high-temperature terrestrial biotopes where sufficient supply of oxidized inorganic nitrogen exists.
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