Precision mapping child undernutrition for nearly 600,000 inhabited census villages in India.

There are emerging opportunities to assess health indicators at truly small areas with increasing availability of data geocoded to micro geographic units and advanced modeling techniques. The utility of such fine-grained data can be fully leveraged if linked to local governance units that are accountable for implementation of programs and interventions. We used data from the 2011 Indian Census for village-level demographic and amenities features and the 2016 Indian Demographic and Health Survey in a bias-corrected semisupervised regression framework to predict child anthropometric failures for all villages in India. Of the total geographic variation in predicted child anthropometric failure estimates, 54.2 to 72.3% were attributed to the village level followed by 20.6 to 39.5% to the state level. The mean predicted stunting was 37.9% (SD: 10.1%; IQR: 31.2 to 44.7%), and substantial variation was found across villages ranging from less than 5% for 691 villages to over 70% in 453 villages. Estimates at the village level can potentially shift the paradigm of policy discussion in India by enabling more informed prioritization and precise targeting. The proposed methodology can be adapted and applied to diverse population health indicators, and in other contexts, to reveal spatial heterogeneity at a finer geographic scale and identify local areas with the greatest needs and with direct implications for actions to take place.

Developing national strategies for reaching men with HIV testing services in Tanzania: results from the male catch-up plan.

BACKGROUND: According to the 2016-2017 Tanzania HIV Impact Survey, 55% of men diagnosed with HIV during the survey self-reported that they were unaware of their HIV status. As a response, the Government of Tanzania launched a Test and Treat campaign in June 2018 with a focus on reaching men and developed the 2018-2020 Male Catch-Up plan. This article reports (1) the enablers and barriers of HIV testing services (HTS) uptake among men (2) and describes the strategies that were proposed as part of the Male Catch-Up Plan to address some of these barriers. METHOD: Qualitative in-depth interviews were conducted with 23 men in Dar es Salaam to explore HTS enablers and barriers. To develop the Male Catch-Up Plan strategies, a desk review of published studies, and analyses of national implementers of HIV/AIDS interventions were conducted. An additional 123 interviews were also carried out with key implementers of HIV/AIDS interventions, healthcare workers, secondary school boys and members of the community in Iringa and Tanga. RESULTS: Enablers of HTS included the desire to check one's health, high HIV risk perception, wanting to protect oneself if tested negative, and being encouraged by their sexual partners. Barriers of HTS were fear of a positive test result, and low HIV risk perception. Proposed strategies from the Male Catch-Up Plan to address these barriers included non-biomedical and biomedical approaches. Non-biomedical strategies are social and cultural approaches to promote an enabling environment to encourage health seeking behavior, safe behavior, and providing peer education programs and social marketing to promote condoms. Biomedical approaches consisted of expanding targeted HIV testing, HIV self-testing, and integrating HIV services with other health services. CONCLUSION: A number of barriers contribute to the low uptake of HTS among men in Tanzania. National strategies have been developed to address these HTS barriers and guide the national Test and Treat campaign focusing on increasing HTS uptake among men.

Carbon monoxide as a metabolic energy source for extremely halophilic microbes: implications for microbial activity in Mars regolith.

Carbon monoxide occurs at relatively high concentrations (≥800 parts per million) in Mars' atmosphere, where it represents a potentially significant energy source that could fuel metabolism by a localized putative surface or near-surface microbiota. However, the plausibility of CO oxidation under conditions relevant for Mars in its past or at present has not been evaluated. Results from diverse terrestrial brines and saline soils provide the first documentation, to our knowledge, of active CO uptake at water potentials (-41 MPa to -117 MPa) that might occur in putative brines at recurrent slope lineae (RSL) on Mars. Results from two extremely halophilic isolates complement the field observations. Halorubrum str. BV1, isolated from the Bonneville Salt Flats, Utah (to our knowledge, the first documented extremely halophilic CO-oxidizing member of the Euryarchaeota), consumed CO in a salt-saturated medium with a water potential of -39.6 MPa; activity was reduced by only 28% relative to activity at its optimum water potential of -11 MPa. A proteobacterial isolate from hypersaline Mono Lake, California, Alkalilimnicola ehrlichii MLHE-1, also oxidized CO at low water potentials (-19 MPa), at temperatures within ranges reported for RSL, and under oxic, suboxic (0.2% oxygen), and anoxic conditions (oxygen-free with nitrate). MLHE-1 was unaffected by magnesium perchlorate or low atmospheric pressure (10 mbar). These results collectively establish the potential for microbial CO oxidation under conditions that might obtain at local scales (e.g., RSL) on contemporary Mars and at larger spatial scales earlier in Mars' history.

Tanning Capacity and Nicotine Dependence Among African Americans.

PURPOSE: Recent findings suggest a link between facultative melanin and nicotine dependence among African Americans. We hypothesized that tanning capacity is associated with the time to first cigarette (TTFC) of the day. METHODS: Using a criterion based sample of 150 adult African American current smokers, reflectometer measures of constitutive and facultative melanin, tanning capacity, smoking status and history, saliva cotinine, sociodemographic characteristics, and stress and discrimination scales were recorded. TTFC was categorized as: 1) within the first 5 min versus more than 5 min; and 2) within the first 30 min versus more than 30 min. Descriptive and multivariate analyses were conducted. RESULTS: Analysis revealed significantly higher tanning capacity among individuals who smoked their first cigarette of the day within the first 5 min of awakening (13.5) than among those who smoked after 5 min (10.3, p = 0.01) and among those who smoked within the first 30 min (12.8 vs. 9.6, p = 0.03) compared to those who initiated after this time point. Multivariate logistic regression indicated that tanning capacity was significantly and positively related (OR = 1.14, 95% CI = 1.05-1.22) to TTFC within the first 5 min and was also significantly related to TTFC within the first 30 min (OR = 1.13, CI = 1.03-1.23). CONCLUSION: Tanning capacity was positively associated with a behavioral measure of nicotine dependence among African American smokers. This association was consistent whether comparing smokers at higher or lower levels of dependence. Future research should examine tanning capacity and other indicators of melanin content with smoking cessation rates and tobacco-attributable health disparities.

Rubrobacter spartanus sp. nov., a moderately thermophilic oligotrophic bacterium isolated from volcanic soil.

Bacterial strain HPK2-2T was isolated from soil adjacent to the caldera of Kilauea Volcano in Hawaii Volcanoes National Park. HPK2-2T is a chemoorganoheterotroph that shows optimal growth at 50 °C (range 45-55 °C) and pH 8.0 (range 5.0-10.0). Sequence analysis of the 16S subunit of the rRNA gene showed that HPK2-2T is most closely related to the type strain of Rubrobactertaiwanensis (ATCC BAA-406T), with which it shared 94.5 % sequence identity. The major fatty acids detected in HPK2-2T were C18 : 0 14-methyl and C16 : 0 12-methyl; internally branched fatty acids such as these are characteristic of the genus Rubrobacter. The only respiratory quinone detected was MK-8, which is the major respiratory quinone for all members of the family Rubrobacteraceae examined thus far. We propose that HPK2-2T represents a novel species of the genus Rubrobacter, for which we propose the name Rubrobacterspartanus (type strain HPK2-2T; DSM 102139T; LMG 29988T).

Causal Inference Methods for Estimating Long-Term Health Effects of Air Quality Regulations.

INTRODUCTION: The regulatory and policy environment surrounding air quality management warrants new types of epidemiological evidence. Whereas air pollution epidemiology has typically informed previous policies with estimates of exposure-response relationships between pollution and health outcomes, new types of evidence can inform current debates about the actual health impacts of air quality regulations. Directly evaluating specific regulatory strategies is distinct from and complements estimating exposure-response relationships; increased emphasis on assessing the effectiveness of well-defined regulatory interventions will enhance the evidence supporting policy decisions. The goal of this report is to provide new analytic perspectives and statistical methods for what we refer to as "direct"-accountability assessment of the effectiveness of specific air quality regulatory interventions. Toward this end, we sharpened many of the distinctions surrounding accountability assessment initially raised by the HEI Accountability Working Group (2003) through discussion, development, and deployment of statistical methods for drawing causal inferences from observational data. The methods and analyses presented here are unified in their focus on anchoring accountability assessment to the estimation of the causal consequences of well-defined actions or interventions. These analytic perspectives are discussed in the context of two direct-accountability case studies pertaining to four different links in the so-called chain of accountability, the related series of events leading from the intervention to the expected outcomes (see Preface; HEI Accountability Working Group 2003). METHODS: The statistical methods described in this report consist of both established methods for drawing causal inferences from observational data and newly developed methods for assessing causal accountability. We have sharpened the analytic distinctions between studies that directly evaluated the effectiveness of specific policies and those that estimated exposure-response relationships between pollution and health. We emphasized how a potential-outcomes paradigm for causal inference can elevate policy debates by means of more direct evidence of the extent to which complex regulatory interventions affect pollution and health outcomes. We also outlined the potential-outcomes perspective and promoted its use as a means to frame observational studies as approximate randomized experiments. Our newly developed methods for assessing causal accountability draw on propensity scores, principal stratification, causal mediation analysis, spatial hierarchical models, and Bayesian estimation. The first case study made use of health outcomes among approximately four million Medicare beneficiaries living in the Western United States to estimate the causal health impacts of areas designated as being in nonattainment for particulate matter ≤10 µm in aerodynamic diameter (PM10*) according to the 1987 National Ambient Air Quality Standards (NAAQS). The second case study focused on developing and testing our new, advanced methodology for multipollutant accountability assessment by examining the extent to which sulfur dioxide (SO2) scrubbers on coal-fired power plants causally affect emissions of SO2, nitrogen oxides (NO(x)), and carbon dioxide (CO2) as well as the extent to which emissions reductions mediate the causal effect of a scrubber on ambient concentrations of PM2.5. Both case studies were anchored in our compilation of national, linked data on ambient air quality monitoring, weather, population demographics, Medicare hospitalization and mortality outcomes, continuous-emissions monitoring for electricity-generating units (EGUs) in power plants, and a variety of regulatory control interventions. The resulting database has unprecedented accuracy and granularity for conducting the types of accountability assessments presented in this report. A key component of our work was the creation of tools to help distribute our linked database and to facilitate reproducible research. RESULTS: In the first case study, we focused on illustrating the most fundamental features of a causal-inference perspective on direct-accountability assessment. The results indicated that all-cause Medicare mortality and respiratory-related hospitalization rates were causally reduced in areas designated as nonattainment for PM10 during 1990 to 1995 compared with the rates that would have occurred without the designation. In the second case study, which examined power-plant emissions and illustrated our newly developed statistical methods, the results indicated that the presence of an SO2 scrubber causally reduced ambient PM2.5 and that this reduction was mediated almost entirely through causal reductions in SO2 emissions. The results were interpreted in light of the well-documented relationships between scrubbers, power-plant emissions, and PM2.5. CONCLUSION: By grounding accountability research in a potential-outcomes framework and applying our new methods to our collection of national data sets, we were able to provide additional sound evidence of the health effects of long-term, large-scale air quality regulations. This additional, rigorous evidence of the causal effects of well-defined actions augments the existing body of research and ensures that the highest-level epidemiological evidence will continue to support regulatory policies. Ultimately, our research contributed to the evidence available to support to the U.S. Environmental Protection Agency (U.S. EPA) and other stakeholders for incorporating health outcomes research into policy development.

Beam intensity reshaping by pump modification in a laser amplifier.

We propose a new technique for laser beam shaping into a desirable beam profile by using a laser amplifier with a pump beam that has a modified intensity profile. We developed the analytical formula, which describes the transformation of the seed beam into the desired beam profile in a four level amplifiers small signal regime. We propose a numerically method to obtain the required pump intensity profile in the case where high pump power saturated the laser crystal or for three level materials. The theory was experimentally verified by one dimensionally shaping a Gaussian shaped seed into a Flat-Top beam in a Ho:YLF amplifier pumped by a Tm:YLF laser with a HG(01) intensity profile.

Determinants of HIV serostatus disclosure to sexual partner among HIV-positive alcohol users in Haiti.

This study examined the relationship between antiretroviral therapy use, participants' knowledge of partner's HIV serostatus, number of sex partners, perceived infectivity and HIV disclosure to a main sexual partner among 258 HIV-positive Haitian alcohol users. Only 38.6 % had disclosed their HIV serostatus to sexual partners. Logistic regression analyses revealed that participants who self-reported having an HIV-negative partner (OR = 0.36, 95 % CI 0.13-0.97) or a partner of unknown HIV status (OR = 0.09, 95 % CI 0.04-0.22) were less likely to disclose their HIV serostatus than participants who self-reported having an HIV-positive partner. Participants who had more than one sexual partner in the past 3 months (OR = 0.41, 95 % CI 0.19-0.90) were also less likely to disclose than participants who had one partner. These findings suggest the need for couples-based programs to assist people living with HIV (PLWH) with the disclosure process, especially among PLWH who have more than one sexual partner and/or are in serodiscordant relationships.

An examination of the HIV serostatus disclosure process among Haitian immigrants in New York City.

Little is known about the HIV serostatus disclosure experience of Haitian immigrants in the USA. We employed the disclosure processes model to examine the disclosure experience of 21 HIV-positive Haitian immigrants in New York City. Data were collected through in-depth interviews conducted between May 2012 and January 2013 with participants from four community-based organizations providing HIV/AIDS services. Analysis of the interviews yielded several enablers relevant to reasons for disclosure including participants being in a close relationship with someone they trusted or felt comfortable with, and the need for support and understanding about the illness. Some of the barriers to HIV serostatus disclosure were fear of being stigmatized, rejected. For participants who had disclosed to significant others in the USA and in Haiti, they reported that they experienced both positive and negative outcomes including social support, emotional relief, encouragement to take their medication, and on some occasions mistreatments, isolation, and stigma. The strategies participants employed during the disclosure event also revealed the additional challenges immigrants face when deciding to disclose their HIV serostatus to family members living in their country of origin. These findings suggest the need to develop culturally appropriate interventions to address the disclosure needs of ethnic minorities residing in the USA.

Cigarette smoking and alcohol use as predictors of HIV testing in the United States: results from the 2010 National Health Interview Survey.

We examined the association between HIV risk perception and HIV testing among cigarette smokers, alcohol users, dual consumers of cigarette and alcohol, and abstainers. Data were analyzed from the 2010 National Health Interview Survey of the full sample of 22,946 and separately for 1547 African Americans. Multivariate logistic regression analysis revealed that alcohol users and dual consumers were significantly more likely to perceive themselves to be at risk of acquiring HIV. Cigarette smokers and alcohol users who considered themselves to be at risk for HIV and dual consumers who reported no perceived HIV risk were more likely to have been tested for HIV than abstainers who perceived no risk of acquiring HIV. Among African Americans, dual consumers and cigarette smokers only who perceived themselves at risk for HIV were more likely to have been tested for HIV than abstainers who perceived no risk of HIV infection. This study demonstrated that among the full sample and African Americans, cigarette smoking and alcohol use were significantly associated with HIV testing regardless of HIV risk perceptions.

Disclosure and impact of maternal HIV+ serostatus on mothers and children in rural Haiti.

Mothers living with HIV (MLWHs) in the United States have reported that one of their main challenges is the decision to disclose their HIV serostatus to their children and the potential consequences of their disclosure. Little is known about the experiences of MLWHs regarding disclosing their HIV serostatus to their children and the impact of maternal HIV serostatus disclosure in the island nations of the Caribbean. Study objectives were to identify the factors influencing maternal HIV serostatus disclosure, examine the breadth of maternal HIV serostatus, and understand the impact of disclosure on mothers and the children. Baseline interviews were conducted between 2006 and 2007 with 25 HIV-positive mothers and 26 children ages 10-17 participating in a pilot psychosocial support intervention for HIV-affected youth and their caregivers in Haiti. Interviews were transcribed verbatim and coded for topical themes by two investigators. Analysis of the interviews yielded several themes relevant to reasons for disclosure, including children's experience of HIV stigma in the community, social support and encouragement from psychosocial intervention workers. The main themes related to breadth of disclosure were brief disclosure and explicit disclosure with some mothers sharing information about how they learned about their illness diagnosis and their medication. Themes related to impacts of disclosure included emotional reactions of children and mothers, and children's desire to assist mothers with illness and become involved. These findings suggest the need to provide more psychosocial support to HIV-affected families in the Caribbean region.

General purpose computer-assisted clustering and conceptualization.

We develop a computer-assisted method for the discovery of insightful conceptualizations, in the form of clusterings (i.e., partitions) of input objects. Each of the numerous fully automated methods of cluster analysis proposed in statistics, computer science, and biology optimize a different objective function. Almost all are well defined, but how to determine before the fact which one, if any, will partition a given set of objects in an "insightful" or "useful" way for a given user is unknown and difficult, if not logically impossible. We develop a metric space of partitions from all existing cluster analysis methods applied to a given dataset (along with millions of other solutions we add based on combinations of existing clusterings) and enable a user to explore and interact with it and quickly reveal or prompt useful or insightful conceptualizations. In addition, although it is uncommon to do so in unsupervised learning problems, we offer and implement evaluation designs that make our computer-assisted approach vulnerable to being proven suboptimal in specific data types. We demonstrate that our approach facilitates more efficient and insightful discovery of useful information than expert human coders or many existing fully automated methods.

Global maternal mortality projections by urban/rural location and education level: a simulation-based analysis.

Background: Maternal mortality remains a challenge in global health, with well-known disparities across countries. However, less is known about disparities in maternal health by subgroups within countries. The aim of this study is to estimate maternal health indicators for subgroups of women within each country. Methods: In this simulation-based analysis, we used the empirically calibrated Global Maternal Health (GMatH) microsimulation model to estimate a range of maternal health indicators by subgroup (urban/rural location and level of education) for 200 countries/territories from 1990 to 2050. Education levels were defined as low (less than primary), middle (less than secondary), and high (completed secondary or higher). The model simulates the reproductive lifecycle of each woman, accounting for individual-level factors such as family planning preferences, biological factors (e.g., anemia), and history of maternal complications, and how these factors vary by subgroup. We also estimated the impact of scaling up women's education on projected maternal health outcomes compared to clinical and health system-focused interventions. Findings: We find large subgroup differences in maternal health outcomes, with an estimated global maternal mortality ratio (MMR) in 2022 of 292 (95% UI 250-341) for rural women and 100 (95% UI 84-116) for urban women, and 536 (95% UI 450-594), 143 (95% UI 117-174), and 85 (95% UI 67-108) for low, middle, and high education levels, respectively. Ensuring all women complete secondary school is associated with a large impact on the projected global MMR in 2030 (97 [95% UI 76-120]) compared to current trends (167 [95% UI 142-188]), with especially large improvements in countries such as Afghanistan, Chad, Madagascar, Niger, and Yemen. Interpretation: Substantial subgroup disparities present a challenge for global maternal health and health equity. Outcomes are especially poor for rural women with low education, highlighting the need to ensure that policy interventions adequately address barriers to care in rural areas, and the importance of investing in social determinants of health, such as women's education, in addition to health system interventions to improve maternal health for all women. Funding: John D. and Catherine T. MacArthur Foundation, 10-97002-000-INP.

Simulation-based estimates and projections of global, regional and country-level maternal mortality by cause, 1990-2050.

Maternal mortality is a major global health challenge. Although progress has been made globally in reducing maternal deaths, measurement remains challenging given the many causes and frequent underreporting of maternal deaths. We developed the Global Maternal Health microsimulation model for women in 200 countries and territories, accounting for individual fertility preferences and clinical histories. Demographic, epidemiologic, clinical and health system data were synthesized from multiple sources, including the medical literature, Civil Registration Vital Statistics systems and Demographic and Health Survey data. We calibrated the model to empirical data from 1990 to 2015 and assessed the predictive accuracy of our model using indicators from 2016 to 2020. We projected maternal health indicators from 1990 to 2050 for each country and estimate that between 1990 and 2020 annual global maternal deaths declined by over 40% from 587,500 (95% uncertainty intervals (UI) 520,600-714,000) to 337,600 (95% UI 307,900-364,100), and are projected to decrease to 327,400 (95% UI 287,800-360,700) in 2030 and 320,200 (95% UI 267,100-374,600) in 2050. The global maternal mortality ratio is projected to decline to 167 (95% UI 142-188) in 2030, with 58 countries above 140, suggesting that on current trends, maternal mortality Sustainable Development Goal targets are unlikely to be met. Building on the development of our structural model, future research can identify context-specific policy interventions that could allow countries to accelerate reductions in maternal deaths.

A simulation-based comparative effectiveness analysis of policies to improve global maternal health outcomes.

The Sustainable Development Goals include a target to reduce the global maternal mortality ratio (MMR) to less than 70 maternal deaths per 100,000 live births by 2030, with no individual country exceeding 140. However, on current trends the goals are unlikely to be met. We used the empirically calibrated Global Maternal Health microsimulation model, which simulates individual women in 200 countries and territories to evaluate the impact of different interventions and strategies from 2022 to 2030. Although individual interventions yielded fairly small reductions in maternal mortality, integrated strategies were more effective. A strategy to simultaneously increase facility births, improve the availability of clinical services and quality of care at facilities, and improve linkages to care would yield a projected global MMR of 72 (95% uncertainty interval (UI) = 58-87) in 2030. A comprehensive strategy adding family planning and community-based interventions would have an even larger impact, with a projected MMR of 58 (95% UI = 46-70). Although integrated strategies consisting of multiple interventions will probably be needed to achieve substantial reductions in maternal mortality, the relative priority of different interventions varies by setting. Our regional and country-level estimates can help guide priority setting in specific contexts to accelerate improvements in maternal health.

Salinity change induces distinct climate feedbacks of nitrogen removal in saline lakes.

Current estimations of nitrogen biogeochemical cycling and N2O emissions in global lakes as well as predictions of their future changes are overrepresented by freshwater datasets, while less consideration is given to widespread saline lakes with different salinity (representing salinization or desalinization). Here, we show that N2O production by denitrification is the main process of reactive nitrogen (Nr, the general abbreviations of NH4+-N, NO2--N and NO3--N) removal in hypersaline lake sediments (e.g. Lake Chaka). The integration of our field measurements and literature data shows that in response to natural salinity decrease, potential Nr removal increases while N2O production decreases. Furthermore, denitrification-induced N2 production exhibits higher salinity sensitivity than denitrification-induced N2O production, suggesting that the contribution of N2O to Nr removal decreases with decreasing salinity. This field-investigation-based salinity response model of Nr removal indicates that under global climate change, saline lakes in the process of salinization or desalination may have distinct Nr removal and climate feedback effects: salinized lakes tend to generate a positive climate feedback, while desalinated lakes show a negative feedback. Therefore, salinity change should be considered as an important factor in assessing future trend of N2O emissions from lakes under climate change.

Multi-level influence of school norms on tobacco use in South Africa: an ecometric consideration of group differences.

OBJECTIVES: Tobacco use has been found to be related to contextual-environmental characteristics. This study focuses on the influence of contextual norms on adolescent smoking behavior with consideration of racial differences. METHODS: Data for this study were derived from the South African Community Epidemiology Network on Drug Use survey. Students (n = 1,277) completed a self-administered questionnaire (available in Afrikaans, Xhosa, and English). School-level aggregate measures were developed from the items: whether they thought smoking was wrong, whether they thought they would be seen as "cool" if they smoked, how many of their closest friends smoked, and whether they had repeated a grade level in school. RESULTS: The results of this analysis revealed that after controlling for demographic characteristics, aggregate measures of importance for ever smoking were whether there were school norms of perceiving that smoking was not wrong, perceiving that smoking was cool, and high prevalence of having friends who smoke. Recent smoking was only predicted by attendance at schools with increased levels of academic failure. Black South Africans were less likely to ever smoke than Coloured or White. CONCLUSIONS: This study highlights the saliency of both compositional (academic failure) and ecological (collective perceptions about smoking) characteristics in predicting ever and recent smoking. Collective perceptions of smoking in a predominantly Black school were largely negative. These findings can be used to target school norms regarding tobacco use in Cape Town.

Putative Nickel-Dependent Anaerobic Carbon Monoxide Uptake Occurs Commonly in Soils and Sediments at Ambient Temperature and Might Contribute to Atmospheric and Sub-Atmospheric Carbon Monoxide Uptake During Anoxic Conditions.

Carbon monoxide (CO) occurs naturally in the atmosphere where it plays a critical role in tropospheric chemistry. Atmospheric CO uptake by soils has been well documented as an important CO sink and has been attributed to a group of aerobic bacteria that possess a molybdenum-dependent CO dehydrogenase (Mo-CODH). CO can also be oxidized by obligate Ni-dependent anaerobes (Ni-COX) that possess nickel-dependent CODHs (Ni-CODH) but relatively little is known about their ecology or their potential to contribute to CO dynamics within soils and sediments or to soil-atmosphere CO exchanges. Results from a series of assays undertaken with diverse soils and sediments and CO concentrations of 10 ppm and 25% with incubation temperatures of 10, 25, and 60°C revealed anaerobic uptake rates with 10 ppm CO that were comparable to those measured under oxic conditions; further, anaerobic CO uptake occurred without a lag and at atmospheric and sub-atmospheric CO concentrations. Assays with 25% CO revealed previously undocumented activity at 10°C and showed extensive activity at 25°C. Results from prior studies with isolates and soils suggest that anaerobic uptake at both 10 ppm and 25% CO concentrations might be attributed to Ni-COX. Collectively the results considerably expand the ecological range for Ni-COX and indicate that they could play previously unsuspected roles in soil CO dynamics.

Short-Term Exposure to Thermophilic Temperatures Facilitates CO Uptake by Thermophiles Maintained under Predominantly Mesophilic Conditions.

Three phylogenetically and phenotypically distinct CO-oxidizing thermophiles (Alicyclobacillus macrosporangiidus CPP55 (Firmicutes), Meiothermus ruber PS4 (Deinococcus-Thermus) and Thermogemmatispora carboxidovorans PM5T (Chloroflexi)) and one CO-oxidizing mesophile (Paraburkholderia paradisi WAT (Betaproteobacteria)) isolated from volcanic soils were used to assess growth responses and CO uptake rates during incubations with constant temperatures (25 °C and 55 °C) and during multi-day incubations with a temperature regime that cycled between 20 °C and 55 °C on a diurnal basis (alternating mesophilic and thermophilic temperatures, AMTT). The results were used to test a conjecture that some thermophiles can survive in mesothermal habitats that experience occasional thermophilic temperatures. Meiothermus ruber PS4, which does not form spores, was able to grow and oxidize CO under all conditions, while the spore-forming Alicyclobacillus macrosporangiidus CPP55 grew and oxidized CO during the AMTT regime and at 55 °C, but was not active at 25 °C. Thermogemmatispora carboxidovorans PM5T, also a spore former, only grew at 55 °C but oxidized CO during AMTT and 55 °C incubations. In contrast, the non-sporing mesophile, Paraburkholderia paradisi WAT, was only able to grow and oxidize CO at 25 °C; growth and CO uptake ceased during the AMTT incubations after exposure to the initial round of thermophilic temperatures. Collectively, these results suggest that temporary, periodic exposure to permissive growth temperatures could help maintain populations of thermophiles in mesothermal habitats after deposition from the atmosphere or other sources.

Distribution and diversity of anaerobic thermophiles and putative anaerobic nickel-dependent carbon monoxide-oxidizing thermophiles in mesothermal soils and sediments.

Even though thermophiles are best known from geothermal and other heated systems, numerous studies have demonstrated that they occur ubiquitously in mesothermal and permanently cold soils and sediments. Cultivation based studies of the latter have revealed that the thermophiles within them are mostly spore-forming members of the Firmicutes. Since the geographic distribution of spores is presumably unconstrained by transport through the atmosphere, similar communities (composition and diversity) of thermophiles might be expected to emerge in mesothermal habitats after they are heated. Alternatively, thermophiles might experience environmental selection before or after heating leading to divergent communities. After demonstrating the ubiquity of anaerobic thermophiles and CO uptake in a variety of mesothermal habitats and two hot springs, we used high throughput sequencing of 16S rRNA genes to assess the composition and diversity of populations that emerged after incubation at 60°C with or without headspace CO concentrations of 25%. Anaerobic Firmicutes dominated relative abundances at most sites but anaerobic thermophilic members of the Acidobacteria and Proteobacteria were also common. Nonetheless, compositions at the amplicon sequence variant (ASV) level varied among the sites with no convergence resulting from heating or CO addition as indicated by beta diversity analyses. The distinctions among thermophilic communities paralleled patterns observed for unheated "time zero" mesothermal soils and sediments. Occupancy analyses showed that the number of ASVs occupying each of n sites decreased unimodally with increasing n; no ASV occupied all 14 sites and only one each occupied 11 and 12 sites, while 69.3% of 1873 ASVs occupied just one site. Nonetheless, considerations of distances among the sites occupied by individual ASVs along with details of their distributions indicated that taxa were not dispersal limited but rather were constrained by environmental selection. This conclusion was supported by ßMNTD and ßNTI analyses, which showed dispersal limitation was only a minor contributor to taxon distributions.