A Standard Practice Protocol for Addressing Depression in a Hospice Setting.

Depression can worsen physical suffering and psychiatric distresses in individuals with life-limiting illnesses and is associated with increased rates of pain, fatigue, dyspnea, and worse survival outcomes. Evidence supports protocol development to address depression in the hospice setting using validated screening tools and a process for referral and treatment. After protocol development and integration of validated screening tools into the electronic medical record, newly admitted patients meeting inclusion criteria were screened during the social workers' initial psychosocial assessment. Patients were referred for pharmacological and nonpharmacological treatment strategies based on the severity of depression detailed in the protocol. Of all patients who met inclusion criteria, 100% were screened using the Patient Health Questionnaire-2 with 52% being identified as having some severity of depression, 26% being appropriately referred for treatment, and 50% receiving a pharmacological strategy, whereas 26% received nonpharmacological strategies. There was a statistically significant difference in severity of depression found between those identified as having a depressed mood preintervention and those with some severity of depression using a validated screening tool postintervention. Implementing a standardized practice protocol to address depression in a hospice setting allowed for consistent evaluation through the use of validated screening tool(s) and increased recognition of those with symptoms of depression.

Molecular discoveries in microbial DMSP synthesis.

Dimethylsulfoniopropionate (DMSP) is one of the Earth's most abundant organosulfur compounds because many marine algae, bacteria, corals and some plants produce it to high mM intracellular concentrations. In these organisms, DMSP acts an anti-stress molecule with purported roles to protect against salinity, temperature, oxidative stress and hydrostatic pressure, amongst many other reported functions. However, DMSP is best known for being a major precursor of the climate-active gases and signalling molecules dimethylsulfide (DMS), methanethiol (MeSH) and, potentially, methane, through microbial DMSP catabolism. DMSP catabolism has been extensively studied and the microbes, pathways and enzymes involved have largely been elucidated through the application of molecular research over the last 17 years. In contrast, the molecular biology of DMSP synthesis is a much newer field, with the first DMSP synthesis enzymes only being identified in the last 5 years. In this review, we discuss how the elucidation of key DMSP synthesis enzymes has greatly expanded our knowledge of the diversity of DMSP-producing organisms, the pathways used, and what environmental factors regulate production, as well as to inform on the physiological roles of DMSP. Importantly, the identification of key DMSP synthesis enzymes in the major groups of DMSP producers has allowed scientists to study the distribution and predict the importance of different DMSP-producing organisms to global DMSP production in diverse marine and sediment environments. Finally, we highlight key challenges for future molecular research into DMSP synthesis that need addressing to better understand the cycling of this important marine organosulfur compound, and its magnitude in the environment.

Expanding access to medications for opioid use disorder through locally-initiated implementation.

BACKGROUND: Despite demonstrated efficacy, medication treatment for opioid use disorder (MOUD) remain inaccessible to many patients, with barriers identified at the individual, clinic and system level. A wide array of implementation strategies have guided efforts to expand access to MOUD, with most centered around externally-facilitated approaches to practice change. While effective, such approaches may be inaccessible to those clinics and systems that lack the resources necessary to partner with an external team, suggesting a need to identify and describe change-processes that are internally developed and promoted. METHODS: Guided by the Consolidated Framework for Implementation Research (CFIR), we utilized qualitative interviews and ethnographic observation to investigate the planning, design and implementation of a locally-initiated process to expand access to MOUD within one health care system. All study documents were coded by a primary coder and secondary reviewer using a codebook designed for use with the CFIR. To analyze data, we reviewed text tagged by key codes, compared these textual excerpts both across and within documents, and organized findings into themes. Processes identified were mapped to established implementation science constructs and strategies. RESULTS: Interviews with clinicians and administrators (n = 9) and ethnographic observation of planning meetings (n = 3) revealed how a self-appointed local team developed, established broad support for, and successfully implemented a Primary Care-based Buprenorphine Clinic and E-Consult Service to expand access to MOUD to patients across the health care system. First, national and local policy changes-including altered clinical practice guidelines, performance pay incentives regarding opioid prescribing, and a directive from VA Central Office increased individual staff and administrators' perception of the need for change and willingness to invest time and resources. Then, a self-appointed interdisciplinary team utilized cross-clinic meetings and information gathering to identify appropriate, and widely supported, models of care delivery and care consultation. Finally, the team increased staff investment in these change efforts by bringing them into the planning process and encouraging collaborative problem solving. CONCLUSIONS: This study reveals how a local team developed and built widespread support for new processes of care that were tailored to local needs and well-positioned for sustainability over time.

Insights into methionine S-methylation in diverse organisms.

Dimethylsulfoniopropionate (DMSP) is an important marine anti-stress compound, with key roles in global nutrient cycling, chemotaxis and, potentially, climate regulation. Recently, diverse marine Actinobacteria, α- and γ-proteobacteria were shown to initiate DMSP synthesis via the methionine (Met) S-methyltransferase enzyme (MmtN), generating S-methyl-Met (SMM). Here we characterize a roseobacterial MmtN, providing structural and mechanistic insights into this DMSP synthesis enzyme. We propose that MmtN uses the proximity and desolvation mechanism for Met S-methylation with two adjacent MmtN monomers comprising the Met binding site. We also identify diverse functional MmtN enzymes in potentially symbiotic archaeal Candidatus Woesearchaeota and Candidate Phyla Radiation (CPR) bacteria, and the animalcule Adineta steineri, not anticipated to produce SMM and/or DMSP. These diverse MmtN enzymes, alongside the larger plant MMT enzyme with an N-terminus homologous to MmtN, likely utilize the same proximity and desolvation mechanism. This study provides important insights into the catalytic mechanism of SMM and/or DMSP production, and proposes roles for these compounds in secondary metabolite production, and SMM cycling in diverse organisms and environments.

Factors Associated with Health Inequalities in Infectious Disease Pandemics Predating COVID-19 in the United States: A Systematic Review.

Objective: Previous pandemics may offer evidence on mediating factors that contributed to disparities in infection and poor outcomes, which could inform the effort to mitigate potential unequal outcomes during the current COVID-19 pandemic. This systematic review sought to examine those factors. Methods: We searched MEDLINE, PsycINFO, and Cochrane to May 2020. We included studies examining health disparities in adult U.S. populations during infectious disease epidemics or pandemics. Two investigators screened abstracts and full text. We assessed study quality using the Newcastle/Ottawa Scale or the Critical Appraisal Skills Programme Checklist for Qualitative Studies. Results: Sixteen articles were included, of which 14 focused on health disparities during the 2009 H1N1 influenza pandemic. Studies showed that disparities during the H1N1 pandemic were more related to differential exposure to the virus than to susceptibility or access to care. Overall, pandemic-related disparities emanate primarily from inequalities in social conditions that place racial and ethnic minorities and low socioeconomic status populations at greater risk of exposure and infection, rather than individual-level factors such as health behaviors and comorbidities. Conclusions: Policy- and systems-level interventions should acknowledge and address these social determinants of heightened risk, and future research should evaluate the effects of such interventions to avoid further exacerbation of health inequities during the current and future pandemics.

Mechanistic insights into the key marine dimethylsulfoniopropionate synthesis enzyme DsyB/DSYB.

Marine algae and bacteria produce approximately eight billion tonnes of the organosulfur molecule dimethylsulfoniopropionate (DMSP) in Earth's surface oceans annually. DMSP is an antistress compound and, once released into the environment, a major nutrient, signaling molecule, and source of climate-active gases. The methionine transamination pathway for DMSP synthesis is used by most known DMSP-producing algae and bacteria. The S-directed S-adenosylmethionine (SAM)-dependent 4-methylthio-2-hydroxybutyrate (MTHB) S-methyltransferase, encoded by the dsyB/DSYB gene, is the key enzyme of this pathway, generating S-adenosylhomocysteine (SAH) and 4-dimethylsulfonio-2-hydroxybutyrate (DMSHB). DsyB/DSYB, present in most haptophyte and dinoflagellate algae with the highest known intracellular DMSP concentrations, is shown to be far more abundant and transcribed in marine environments than any other known S-methyltransferase gene in DMSP synthesis pathways. Furthermore, we demonstrate in vitro activity of the bacterial DsyB enzyme from Nisaea denitrificans and provide its crystal structure in complex with SAM and SAH-MTHB, which together provide the first important mechanistic insights into a DMSP synthesis enzyme. Structural and mutational analyses imply that DsyB adopts a proximity and desolvation mechanism for the methyl transfer reaction. Sequence analysis suggests that this mechanism may be common to all bacterial DsyB enzymes and also, importantly, eukaryotic DSYB enzymes from e.g., algae that are the major DMSP producers in Earth's surface oceans.

Adjunct interventions to standard medical management of buprenorphine in outpatient settings: A systematic review of the evidence.

BACKGROUND: A growing body of research has examined adjunctive interventions supportive of engagement and retention in treatment among patients receiving buprenorphine for opioid use disorder (OUD). We conducted a systematic review of the literature addressing the effect on key outcomes of adjunctive interventions provided alongside standard medical management of buprenorphine in outpatient settings. METHODS: We included prospective studies examining adults receiving buprenorphine paired with an adjunctive intervention for the treatment of OUD in an outpatient setting. Data sources included Medline, Cochrane Central Register of Controlled Trials, CINAHL and PsycINFO from inception through January 2020. Two raters independently reviewed full-text articles, abstracted data and appraised risk of bias. Outcomes examined included abstinence, retention in treatment and non-addiction-related health outcomes. RESULTS: The final review includes 20 manuscripts, 11 randomized control trials (RCTs), three secondary analyses of RCTs and six observational studies. Most studies examined psychosocial interventions (n = 14). Few examined complementary therapies (e.g., yoga; n = 2) or technological interventions (e.g., electronic pill dispensation; n = 3); one study examined an intervention addressing structural barriers to care (patient navigators; n = 1). Low risk of bias RCTs found no evidence that adding psychosocial interventions to buprenorphine treatment improves substance use outcomes. CONCLUSIONS: Research is needed to identify adjunctive interventions with potential to support medication adherence and addiction-related outcomes for patients engaged in buprenorphine treatment. Data from clinical trials suggest that lack of ready access to psychosocial treatments should not discourage clinicians from prescribing buprenorphine.

Bacterial Dimethylsulfoniopropionate Biosynthesis in the East China Sea.

Dimethylsulfoniopropionate (DMSP) is one of Earth's most abundant organosulfur molecules. Recently, many marine heterotrophic bacteria were shown to produce DMSP, but few studies have combined culture-dependent and independent techniques to study their abundance, distribution, diversity and activity in seawater or sediment environments. Here we investigate bacterial DMSP production potential in East China Sea (ECS) samples. Total DMSP (DMSPt) concentration in ECS seawater was highest in surface waters (SW) where phytoplankton were most abundant, and it decreased with depth to near bottom waters. However, the percentage of DMSPt mainly apportioned to bacteria increased from the surface to the near bottom water. The highest DMSP concentration was detected in ECS oxic surface sediment (OSS) where phytoplankton were not abundant. Bacteria with the genetic potential to produce DMSP and relevant biosynthesis gene transcripts were prominent in all ECS seawater and sediment samples. Their abundance also increased with depth and was highest in the OSS samples. Microbial enrichments for DMSP-producing bacteria from sediment and seawater identified many novel taxonomic groups of DMSP-producing bacteria. Different profiles of DMSP-producing bacteria existed between seawater and sediment samples and there are still novel DMSP-producing bacterial groups to be discovered in these environments. This study shows that heterotrophic bacteria significantly contribute to the marine DMSP pool and that their contribution increases with water depth and is highest in seabed surface sediment where DMSP catabolic potential is lowest. Furthermore, distinct bacterial groups likely produce DMSP in seawater and sediment samples, and many novel producing taxa exist, especially in the sediment.

Disparities in H1N1 Vaccination Rates: a Systematic Review and Evidence Synthesis to Inform COVID-19 Vaccination Efforts.

BACKGROUND: Data suggest that there were disparities in H1N1 vaccine uptake, and these may inform COVID-19 vaccination efforts. We conducted a systematic review to evaluate disparities in H1N1 vaccine uptake, factors contributing to disparities, and interventions to reduce them. METHODS: We searched English-language articles in MEDLINE ALL, PsycINFO, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials from database inception through May 8, 2020. Observational studies examining H1N1 vaccine uptake by race/ethnicity, socioeconomic status, rurality, and disability status in US settings were included. Two reviewers independently assessed study eligibility. Single-reviewer data abstraction was confirmed by a second reviewer. We conducted independent dual quality assessment, and collective strength of evidence assessment. RESULTS: We included 21 studies. African American/Black, Latino, and low-socioeconomic status participants had disproportionately lower H1N1 vaccination rates (low- to moderate-strength evidence). However, Latinos were more likely than Whites to intend to be vaccinated, and African American/Blacks and participants with lower-socioeconomic status were just as likely to intend to be vaccinated as their White and higher-socioeconomic status counterparts (low-strength evidence). Vaccine uptake for other groups has been insufficiently studied. Factors potentially contributing to disparities in vaccine uptake included barriers to vaccine access, inadequate information, and concerns about vaccine safety and efficacy. Studies were largely cross-sectional. Many of the studies are a decade old and were conducted in the context of a different pandemic. The categorization of racial and ethnic groups was not consistent across studies and not all groups were well-studied. DISCUSSION: Efforts to avoid disparities in COVID-19 vaccination uptake should prioritize vaccine accessibility and convenience in African American/Black, Latino, and low-SES communities; engage trusted stakeholders to share vaccine information; and address concerns about vaccine safety and efficacy. PRIMARY FUNDING SOURCE: Department of Veterans Affairs, Veterans Health Administration, Health Services Research & Development. PROTOCOL REGISTRATION: PROSPERO CRD42020187078.

Preventing Unequal Health Outcomes in COVID-19: A Systematic Review of Past Interventions.

Background: We sought to identify interventions that reduced disparities in health outcomes in infectious disease outbreaks or natural disasters in the United States to understand whether these interventions could reduce health disparities in the current COVID-19 pandemic. Methods: We searched MEDLINE and other databases to May 2020 to find studies that examined interventions to mitigate health inequalities in previous infectious disease pandemics or disasters. We assessed study quality using the Newcastle-Ottawa Scale and the Critical Appraisal Skills Program (CASP) Checklist for Qualitative Studies. Results: We included 14 articles (12 studies) and 5 Centers for Disease Control (CDC) stakeholder meeting articles on pandemic influenza preparedness in marginalized populations. Studies called for intervention and engagement before pandemic or disaster onset. Several studies included interventions that could be adapted to COVID-19, including harnessing technology to reach disadvantaged populations, partnering with trusted community liaisons to deliver important messaging around disease mitigation, and using culturally specific communication methods and messages to best reach marginalized groups. Discussion: To our knowledge this is the first systematic review to examine interventions to mitigate health inequities during an infectious disease pandemic. However, given that we identified very few disparities-focused infectious disease intervention studies, we also included studies from the disaster response literature, which may not be as generalizable to the current context of COVID-19. Overall, community outreach and tailored communication are essential in disease mitigation. More research is needed to evaluate systemic interventions that target the distal determinants of poor health outcomes among marginalized populations during pandemics and natural disasters.

Training using a simulation-based workshop reduces inaccuracies in estimations of testicular volume.

OBJECTIVES: Measuring testicular volume (TV) by orchidometer is routine in the clinic when staging male puberty. We have developed a simulation model for TV estimation and investigated whether training medical students, using a workshop with simulation models, could improve the accuracy and reliability of TV estimation. METHODS: All participating medical students watched a video representing standard undergraduate training in male pubertal assessment. Volunteers were then randomised directly to assessment or to attend a workshop consisting of a further video and four stations contextualising and practising the skills required for TV estimation, prior to assessment. Three child mannequins displaying testes of 3 mL, 4 mL (twice), 5, 10 and 20 mL were used for assessment. Participants were asked to return a fortnight later for repeat assessment to assess intra-observer reliability, the effect of repeated examinations on accuracy and time on skill retention. RESULTS: Ninety students participated (55F), 46 attended the workshop and were considered "trained". There was no difference between the groups in numbers of correct estimations (29% trained, 27% untrained, p=0.593). However, the trained group's estimations were closer to the true volume, with more from the trained group one bead away (p=0.002) and fewer more than three beads away from the true volume (p<0.001), compared to the untrained group. Trained participants were more accurate at the second assessment (n=80) (p<0.001) and had greater intra-observer reliability (p=0.004). CONCLUSIONS: Overall TV estimation accuracy was poor. Workshop-style training improved accuracy, reliability and retention of skill acquisition and could be considered as a useful learning tool.

Bacteria are important dimethylsulfoniopropionate producers in marine aphotic and high-pressure environments.

Dimethylsulfoniopropionate (DMSP) is an important marine osmolyte. Aphotic environments are only recently being considered as potential contributors to global DMSP production. Here, our Mariana Trench study reveals a typical seawater DMSP/dimethylsulfide (DMS) profile, with highest concentrations in the euphotic zone and decreased but consistent levels below. The genetic potential for bacterial DMSP synthesis via the dsyB gene and its transcription is greater in the deep ocean, and is highest in the sediment.s DMSP catabolic potential is present throughout the trench waters, but is less prominent below 8000 m, perhaps indicating a preference to store DMSP in the deep for stress protection. Deep ocean bacterial isolates show enhanced DMSP production under increased hydrostatic pressure. Furthermore, bacterial dsyB mutants are less tolerant of deep ocean pressures than wild-type strains. Thus, we propose a physiological function for DMSP in hydrostatic pressure protection, and that bacteria are key DMSP producers in deep seawater and sediment.

Initial Impact of COVID-19 on Radiology Practices: An ACR/RBMA Survey.

PURPOSE: The coronavirus disease 2019 (COVID-19) pandemic affected radiology practices in many ways. The aim of this survey was to estimate declines in imaging volumes and financial impact across different practice settings during April 2020. METHODS: The survey, comprising 48 questions, was conducted among members of the ACR and the Radiology Business Management Association during May 2020. Survey questions focused on practice demographics, volumes, financials, personnel and staff adjustments, and anticipation of recovery. RESULTS: During April 2020, nearly all radiology practices reported substantial (56.4%-63.7%) declines in imaging volumes, with outpatient imaging volumes most severely affected. Mean gross charges declined by 50.1% to 54.8% and collections declined by 46.4% to 53.9%. Percentage reductions did not correlate with practice size. The majority of respondents believed that volumes would recover but not entirely (62%-88%) and anticipated a short-term recovery, with a surge likely in the short term due to postponement of elective imaging (52%-64%). About 16% of respondents reported that radiologists in their practices tested positive for COVID-19. More than half (52.3%) reported that availability of personal protective equipment had become an issue or was inadequate. A majority (62.3%) reported that their practices had existing remote reading or teleradiology capabilities in place before the pandemic, and 22.3% developed such capabilities in response to the pandemic. CONCLUSIONS: Radiology practices across different settings experienced substantial declines in imaging volumes and collections during the initial wave of the COVID-19 pandemic in April 2020. Most are actively engaged in both short- and long-term operational adjustments.

Publisher Correction: Marine microbiology: A day in the life of marine sulfonates.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Bacteria are important dimethylsulfoniopropionate producers in coastal sediments.

Dimethylsulfoniopropionate (DMSP) and its catabolite dimethyl sulfide (DMS) are key marine nutrients1,2 that have roles in global sulfur cycling2, atmospheric chemistry3, signalling4,5 and, potentially, climate regulation6,7. The production of DMSP was previously thought to be an oxic and photic process that is mainly confined to the surface oceans. However, here we show that DMSP concentrations and/or rates of DMSP and DMS synthesis are higher in surface sediment from, for example, saltmarsh ponds, estuaries and the deep ocean than in the overlying seawater. A quarter of bacterial strains isolated from saltmarsh sediment produced DMSP (up to 73 mM), and we identified several previously unknown producers of DMSP. Most DMSP-producing isolates contained dsyB8, but some alphaproteobacteria, gammaproteobacteria and actinobacteria used a methionine methylation pathway independent of DsyB that was previously only associated with higher plants. These bacteria contained a methionine methyltransferase gene (mmtN)-a marker for bacterial synthesis of DMSP through this pathway. DMSP-producing bacteria and their dsyB and/or mmtN transcripts were present in all of the tested seawater samples and Tara Oceans bacterioplankton datasets, but were much more abundant in marine surface sediment. Approximately 1 × 108 bacteria g-1 of surface marine sediment are predicted to produce DMSP, and their contribution to this process should be included in future models of global DMSP production. We propose that coastal and marine sediments, which cover a large part of the Earth's surface, are environments with high levels of DMSP and DMS productivity, and that bacteria are important producers of DMSP and DMS within these environments.

Life projects: the transformative potential of direct-acting antiviral treatment for hepatitis C among people who inject drugs.

BACKGROUND AND OBJECTIVES: People who inject drugs (PWID) are disproportionately affected by chronic hepatitis C (HCV) in high-income countries. The advent of direct-acting antivirals (DAAs) makes treatment of this underserved population more possible than ever. The dearth of programs adapted to the needs of PWID and stigma associated with drug use and chronic HCV pose significant barriers to the effective uptake of treatment among this population. We employed "life projects" as a conceptual framework to examine the social incentives of PWID being treated for HCV. This study advances the existing literature on the transformative potential of HCV treatment among PWID, explores how these transformations may affect treatment success, and discusses implications for decisions around whether and when to treat PWID. METHODS: We conducted in-depth interviews with participants of a pilot clinical trial testing the effective delivery of DAA treatment to PWID within two healthcare for the homeless clinic settings - one group receiving opioid agonist therapy (OAT) and another group frequenting a needle and syringe exchange program (NSP). A purposive sample of 27 participants was selected based on place of care. Interviews were transcribed, coded, and analysed for patterns using a priori domains and emergent themes. RESULTS: Participants in both treatment groups described significant life projects that motivated them to complete HCV treatment. These projects included social redemption, strengthening of relationships, pursuit of abstinence from substance use, and harm reduction. These themes were consistent between treatment groups, though more participants in the syringe exchange group relied on harm reduction than on pursuing abstinence to prevent reinfection after achieving virologic cure. CONCLUSION: Understanding the incentives that propel PWID to complete HCV treatment could help to enhance treatment uptake and adherence through dedicated programs that address current barriers to care.

Author Correction: DSYB catalyses the key step of dimethylsulfoniopropionate biosynthesis in many phytoplankton.

In the version of this Letter originally published, the Methods incorrectly stated that all phytoplankton cultures were sampled in mid-exponential phase. The low-nitrogen cultures were sampled in early stationary phase and at the point at which Fv/Fm values decreased, to indicate that cultures were experiencing low-nitrogen conditions. All other phytoplankton cultures were sampled in exponential phase. Growth and Fv/Fm data are provided here on high- and low-nitrogen cultures (Figs 1, 2 and 3) to clarify and support this correction. The Methods also stated that cell counting was done using a Beckman Multisizer 3 Coulter Counter, but a CASY Model TT Cell Counter was used.

DSYB catalyses the key step of dimethylsulfoniopropionate biosynthesis in many phytoplankton.

Dimethylsulfoniopropionate (DMSP) is a globally important organosulfur molecule and the major precursor for dimethyl sulfide. These compounds are important info-chemicals, key nutrients for marine microorganisms, and are involved in global sulfur cycling, atmospheric chemistry and cloud formation1-3. DMSP production was thought to be confined to eukaryotes, but heterotrophic bacteria can also produce DMSP through the pathway used by most phytoplankton 4 , and the DsyB enzyme catalysing the key step of this pathway in bacteria was recently identified 5 . However, eukaryotic phytoplankton probably produce most of Earth's DMSP, yet no DMSP biosynthesis genes have been identified in any such organisms. Here we identify functional dsyB homologues, termed DSYB, in many phytoplankton and corals. DSYB is a methylthiohydroxybutryate methyltransferase enzyme localized in the chloroplasts and mitochondria of the haptophyte Prymnesium parvum, and stable isotope tracking experiments support these organelles as sites of DMSP synthesis. DSYB transcription levels increased with DMSP concentrations in different phytoplankton and were indicative of intracellular DMSP. Identification of the eukaryotic DSYB sequences, along with bacterial dsyB, provides the first molecular tools to predict the relative contributions of eukaryotes and prokaryotes to global DMSP production. Furthermore, evolutionary analysis suggests that eukaryotic DSYB originated in bacteria and was passed to eukaryotes early in their evolution.

Methanethiol-dependent dimethylsulfide production in soil environments.

Dimethylsulfide (DMS) is an environmentally important trace gas with roles in sulfur cycling, signalling to higher organisms and in atmospheric chemistry. DMS is believed to be predominantly produced in marine environments via microbial degradation of the osmolyte dimethylsulfoniopropionate (DMSP). However, significant amounts of DMS are also generated from terrestrial environments, for example, peat bogs can emit ~6 µmol DMS m-2 per day, likely via the methylation of methanethiol (MeSH). A methyltransferase enzyme termed 'MddA', which catalyses the methylation of MeSH, generating DMS, in a wide range of bacteria and some cyanobacteria, may mediate this process, as the mddA gene is abundant in terrestrial metagenomes. This is the first study investigating the functionality of MeSH-dependent DMS production (Mdd) in a wide range of aerobic environments. All soils and marine sediment samples tested produced DMS when incubated with MeSH. Cultivation-dependent and cultivation-independent methods were used to assess microbial community changes in response to MeSH addition in a grassland soil where 35.9% of the bacteria were predicted to contain mddA. Bacteria of the genus Methylotenera were enriched in the presence of MeSH. Furthermore, many novel Mdd+ bacterial strains were isolated. Despite the abundance of mddA in the grassland soil, the Mdd pathway may not be a significant source of DMS in this environment as MeSH addition was required to detect DMS at only very low conversion rates.