Work-related psychosocial demands related to work organization in small sized companies (SMEs) providing health-oriented services in Germany - a qualitative analysis.

BACKGROUND: Micro, small and medium-sized enterprises (SMEs) represent the majority of businesses in the EU. Little is known about psychosocial demands faced by company owners, managers, and employees in SMEs, especially in the health and service sector. The current study aimed to identify which psychosocial demands related to work organization are reported by managers and employees in the health and service sector, and if managers and employees differ in their perspective on these psychosocial demands. METHODS: We conducted nine single interviews and two focus group discussions with seven company owners and managers as well as eleven employees from six different German companies between January and February 2020. The psychosocial factors of the psychosocial risk assessment of the Joint German Occupational Safety and Health Strategy (GDA) served as a framework for data collection and analysis. The interview material was analysed using Mayring's method of qualitative content analysis. RESULTS: We identified four prevailing work-related psychosocial demands related to work organization among managers and employees: (1) possibilities and time for recovery after work, (2) communication and cooperation, (3) work intensity, and (4) interruptions, and prioritization. According to the managers, they were confronted with a lack of possibilities and time for recovery after work. They report issues related to inadequate communication and cooperation affecting the entire company team, and also face high work intensity and frequent interruptions and prioritization. Employees reported a clearer division between work and private life. However, they also face periods of high work intensity, frequent interruptions and the need for prioritization. CONCLUSION: Managers and employees in SMEs in the health and service sector would benefit from evidence-based and evaluated tailored interventions and approaches for improved work organization. Further studies are needed to support managers and employees in SMEs in the health and service sector in facing and handling work-related psychosocial demands like lack of possibilities and time for recovery after work, high work intensity or frequent interruptions.

General Principles for Yield Optimization of Nucleoside Phosphorylase-Catalyzed Transglycosylations.

The biocatalytic synthesis of natural and modified nucleosides with nucleoside phosphorylases offers the protecting-group-free direct glycosylation of free nucleobases in transglycosylation reactions. This contribution presents guiding principles for nucleoside phosphorylase-mediated transglycosylations alongside mathematical tools for straightforward yield optimization. We illustrate how product yields in these reactions can easily be estimated and optimized using the equilibrium constants of phosphorolysis of the nucleosides involved. Furthermore, the varying negative effects of phosphate on transglycosylation yields are demonstrated theoretically and experimentally with several examples. Practical considerations for these reactions from a synthetic perspective are presented, as well as freely available tools that serve to facilitate a reliable choice of reaction conditions to achieve maximum product yields in nucleoside transglycosylation reactions.

Spectral Unmixing-Based Reaction Monitoring of Transformations between Nucleosides and Nucleobases.

The increased interest in (enzymatic) transformations between nucleosides and nucleobases has demanded the development of efficient analytical tools. In this report, we present an update and extension of our recently described method for monitoring these reactions by spectral unmixing. The presented method uses differences in the UV absorption spectra of nucleosides and nucleobases after alkaline quenching to derive their ratio based on spectral shape by fitting normalized reference spectra. It is applicable to a broad compound spectrum comprising more than 35 examples, offers HPLC-like accuracy, ease of handling and significant reductions in both cost and data acquisition time compared to other methods. This contribution details the principle of monitoring reactions by spectral unmixing, gives recommendations regarding solutions to common problems and applications that necessitate special sample treatment. We provide software, workflows and reference spectra that facilitate the straightforward and versatile application of the method.

Rare genital malformations in women's health research: sociodemographic, regional, and disease-related characteristics of patients with Mayer-Rokitansky-Küster-Hauser syndrome.

BACKGROUND: The Mayer-Rokitansky-Küster-Hauser syndrome, MRKHS, is a rare (orphan) disease characterized by the aplasia or hypoplasia of the uterus and the vagina. In women's health research, little is known as to how much care provision for patients with MRKHS takes into account their socio-demographic together with their clinical characteristics. This work examines the patients' socio-demographic characteristics, highlighting issues of inappropriate and deficient provision of care. METHODS: The study was carried out as part of the larger TransCareO project and included a group of N=129 MRKHS patients who underwent surgery between 2008 and 2012. Using a specially developed questionnaire, we analyzed MRKHS patients' data found both in the clinical documentation of the Department for Women's Health, University Hospital of Tübingen and the patient surveys of the Center for Rare Genital Malformations (CRGM/ ZSGF). Patients who took part in interviews were compared with non-respondents. RESULTS: Patient respondents and non-respondents did not differ as to the parameters of interest. In most cases, primary amenorrhea was reported as an admission reason. In 24% of patients, a medical intervention (hymenal incision or hormone treatment) already occurred before admission to the Center in Tübingen and proper diagnosis of MRKHS. About one third received in advance inappropriate treatment. During the therapy, more than half of the patients were in a solid partnership. 10% of the family anamneses documented the occurrence of urogenital malformations. CONCLUSIONS: Care provision for MRKHS patients is largely characterized by delayed proper diagnosis and in part, by inappropriate treatment attempts; there are also indications of regional differences. Anamnestic clues such as an asymptomatic amenorrhea or renal abnormalities of unclear origin still fail to result early enough in referral to a center on the basis of suspected MRKHS diagnosis. Urogenital malformations in the family are more common in patients than in the general population. For patients, a wide range of burdens are associated with the diagnosis. Abnormalities compared to their female peers occur, for instance, in the partnership status: MRKHS patients have more rarely a partner.

Correction to: Healthcare professionals' perspectives on working conditions, leadership, and safety climate: a cross-sectional study.

In the original publication of this article [1], the authors missed that reverse coding was necessary for the item "Do you work separate from your colleagues?" before calculating the scale 'social relations'. So they corrected the analysis accordingly. The results with the revised scale show that there are no longer any significant differences between nurses and physicians with regard to this scale.

Efficient Biocatalytic Synthesis of Dihalogenated Purine Nucleoside Analogues Applying Thermodynamic Calculations.

The enzymatic synthesis of nucleoside analogues has been shown to be a sustainable and efficient alternative to chemical synthesis routes. In this study, dihalogenated nucleoside analogues were produced by thermostable nucleoside phosphorylases in transglycosylation reactions using uridine or thymidine as sugar donors. Prior to the enzymatic process, ideal maximum product yields were calculated after the determination of equilibrium constants through monitoring the equilibrium conversion in analytical-scale reactions. Equilibrium constants for dihalogenated nucleosides were comparable to known purine nucleosides, ranging between 0.071 and 0.081. To achieve 90% product yield in the enzymatic process, an approximately five-fold excess of sugar donor was needed. Nucleoside analogues were purified by semi-preparative HPLC, and yields of purified product were approximately 50% for all target compounds. To evaluate the impact of halogen atoms in positions 2 and 6 on the antiproliferative activity in leukemic cell lines, the cytotoxic potential of dihalogenated nucleoside analogues was studied in the leukemic cell line HL-60. Interestingly, the inhibition of HL-60 cells with dihalogenated nucleoside analogues was substantially lower than with monohalogenated cladribine, which is known to show high antiproliferative activity. Taken together, we demonstrate that thermodynamic calculations and small-scale experiments can be used to produce nucleoside analogues with high yields and purity on larger scales. The procedure can be used for the generation of new libraries of nucleoside analogues for screening experiments or to replace the chemical synthesis routes of marketed nucleoside drugs by enzymatic processes.

Healthcare professionals' perspectives on working conditions, leadership, and safety climate: a cross-sectional study.

BACKGROUND: Promoting patient and occupational safety are two key challenges for hospitals. When aiming to improve these two outcomes synergistically, psychosocial working conditions, leadership by hospital management and supervisors, and perceptions of patient and occupational safety climate have to be considered. Recent studies have shown that these key topics are interrelated and form a critical foundation for promoting patient and occupational safety in hospitals. So far, these topics have mainly been studied independently from each other. The present study investigated hospital staffs' perceptions of four different topics: (1) psychosocial working conditions, (2) leadership, (3) patient safety climate, and (4) occupational safety climate. We present results from a survey in two German university hospitals aiming to detect differences between nurses and physicians. METHODS: We performed a cross-sectional study using a standardized paper-based questionnaire. The survey was conducted with nurses and physicians to assess the four topics. The instruments mainly consisted of scales of the German version of the COPSOQ (Copenhagen Psychosocial Questionnaire), one scale of the Copenhagen Burnout Inventory (CBI), scales to assess leadership and transformational leadership, scales to assess patient safety climate using the Hospital Survey on Patient Safety Culture (HSPSC), and analogous items to assess occupational safety climate. RESULTS: A total of 995 completed questionnaires out of 2512 distributed questionnaires were returned anonymously. The overall response rate was 39.6%. The sample consisted of 381 physicians and 567 nurses. We found various differences with regard to the four topics. In most of the COPSOQ and the HSPSC-scales, physicians rated psychosocial working conditions and patient safety climate more positively than nurses. With regard to occupational safety, nurses indicated higher occupational risks than physicians. CONCLUSIONS: The WorkSafeMed study combined the assessment of the four topics psychosocial working conditions, leadership, patient safety climate, and occupational safety climate in hospitals. Looking at the four topics provides an overview of where improvements in hospitals may be needed for nurses and physicians. Based on these results, improvements in working conditions, patient safety climate, and occupational safety climate are required for health care professionals in German university hospitals - especially for nurses.

RNA interference-based functional knockdown of the voltage-gated potassium channel Kv7.2 in dorsal root ganglion neurons after in vitro and in vivo gene transfer by adeno-associated virus vectors.

Activation of the neuronal potassium channel Kv7.2 encoded by the KCNQ2 gene has recently been shown to be an attractive mechanism to inhibit nociceptive transmission. However, potent, selective, and clinically proven activators of Kv7.2/Kv7.3 currents with analgesic properties are still lacking. An important prerequisite for the development of new drugs is a model to test the selectivity of novel agonists by abrogating Kv7.2/Kv7.3 function. Since constitutive knockout mice are not viable, we developed a model based on RNA interference-mediated silencing of KCNQ2. By delivery of a KCNQ2-specific short hairpin RNA with adeno-associated virus vectors, we completely abolished the activity of the specific Kv7.2/Kv7.3-opener ICA-27243 in rat sensory neurons. Results obtained in the silencing experiments were consistent between freshly prepared and cryopreserved dorsal root ganglion neurons, as well as in dorsal root ganglion neurons dissociated and cultured after in vivo administration of the silencing vector by intrathecal injections into rats. Interestingly, the tested associated virus serotypes substantially differed with respect to their transduction capability in cultured neuronal cell lines and primary dorsal root ganglion neurons and the in vivo transfer of transgenes by intrathecal injection of associated virus vectors. However, our study provides the proof-of-concept that RNA interference-mediated silencing of KCNQ2 is a suitable approach to create an ex vivo model for testing the specificity of novel Kv7.2/Kv7.3 agonists.

Identification and characterization of RNA guanine-quadruplex binding proteins.

Guanine quadruplex (G-quadruplex) motifs in the 5' untranslated region (5'-UTR) of mRNAs were recently shown to influence the efficiency of translation. In the present study, we investigate the interaction between cellular proteins and the G-quadruplexes located in two mRNAs (MMP16 and ARPC2). Formation of the G-quadruplexes was confirmed by biophysical characterization and the inhibitory activity on translation was shown by luciferase reporter assays. In experiments with whole cell extracts from different eukaryotic cell lines, G-quadruplex-binding proteins were isolated by pull-down assays and subsequently identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. The binding partners of the RNA G-quadruplexes we discovered included several heterogeneous nuclear ribonucleoproteins, ribosomal proteins, and splicing factors, as well as other proteins that have previously not been described to interact with nucleic acids. While most of the proteins were specific for either of the investigated G-quadruplexes, some of them bound to both motifs. Selected candidate proteins were subsequently produced by recombinant expression and dissociation constants for the interaction between the proteins and RNA G-quadruplexes in the low nanomolar range were determined by surface plasmon resonance spectroscopy. The present study may thus help to increase our understanding of the mechanisms by which G-quadruplexes regulate translation.

Anaerobic microbial transformation of halogenated aromatics and fate prediction using electron density modeling.

Halogenated homo- and heterocyclic aromatics including disinfectants, pesticides and pharmaceuticals raise concern as persistent and toxic contaminants with often unknown fate. Remediation strategies and natural attenuation in anaerobic environments often build on microbial reductive dehalogenation. Here we describe the transformation of halogenated anilines, benzonitriles, phenols, methoxylated, or hydroxylated benzoic acids, pyridines, thiophenes, furoic acids, and benzenes by Dehalococcoides mccartyi strain CBDB1 and environmental fate modeling of the dehalogenation pathways. The compounds were chosen based on structural considerations to investigate the influence of functional groups present in a multitude of commercially used halogenated aromatics. Experimentally obtained growth yields were 0.1 to 5 × 10(14) cells mol(-1) of halogen released (corresponding to 0.3-15.3 g protein mol(-1) halogen), and specific enzyme activities ranged from 4.5 to 87.4 nkat mg(-1) protein. Chlorinated electron-poor pyridines were not dechlorinated in contrast to electron-rich thiophenes. Three different partial charge models demonstrated that the regioselective removal of halogens is governed by the least negative partial charge of the halogen. Microbial reaction pathways combined with computational chemistry and pertinent literature findings on Co(I) chemistry suggest that halide expulsion during reductive dehalogenation is initiated through single electron transfer from B12Co(I) to the apical halogen site.

Proton transfer in the K-channel analog of B-type Cytochrome c oxidase from Thermus thermophilus.

A key enzyme in aerobic metabolism is cytochrome c oxidase (CcO), which catalyzes the reduction of molecular oxygen to water in the mitochondrial and bacterial membranes. Substrate electrons and protons are taken up from different sides of the membrane and protons are pumped across the membrane, thereby generating an electrochemical gradient. The well-studied A-type CcO uses two different entry channels for protons: the D-channel for all pumped and two consumed protons, and the K-channel for the other two consumed protons. In contrast, the B-type CcO uses only a single proton input channel for all consumed and pumped protons. It has the same location as the A-type K-channel (and thus is named the K-channel analog) without sharing any significant sequence homology. In this study, we performed molecular-dynamics simulations and electrostatic calculations to characterize the K-channel analog in terms of its energetic requirements and functionalities. The function of Glu-15B as a proton sink at the channel entrance is demonstrated by its rotational movement out of the channel when it is deprotonated and by its high pKA value when it points inside the channel. Tyr-244 in the middle of the channel is identified as the valve that ensures unidirectional proton transfer, as it moves inside the hydrogen-bond gap of the K-channel analog only while being deprotonated. The electrostatic energy landscape was calculated for all proton-transfer steps in the K-channel analog, which functions via proton-hole transfer. Overall, the K-channel analog has a very stable geometry without large energy barriers.

The Predominance of the Health-Promoting Patterns of Work Behavior and Experience in General Practice Teams-Results of the IMPROVEjob Study.

This study aims to identify the distribution of the "Work-related behavior and experience patterns" (Arbeitsbezogenes Verhaltens-und Erlebnismuster, AVEM) in general practitioners and their teams by using baseline data of the IMPROVEjob study. Members of 60 general practices with 84 physicians in a leadership position, 28 employed physicians, and 254 practice assistants participated in a survey in 2019 and 2020. In this analysis, we focused on AVEM variables. Age, practice years, work experience, and working time were used as control variables in the Spearman Rho correlations and analysis of variance. The majority of the participants (72.1%) revealed a health-promoting pattern (G or S). Three of eleven AVEM dimensions were above the norm for the professional group "employed physicians". The AVEM dimensions "striving for perfection" (p < 0.001), "experience of success at work" (p < 0.001), "satisfaction with life" (p = 0.003), and "experience of social support" (p = 0.019) differed significantly between the groups' practice owners and practice assistants, with the practice owners achieving the higher values, except for experience of social support. Practice affiliation had no effect on almost all AVEM dimensions. We found a high prevalence of AVEM health-promoting patterns in our sample. Nearly half of the participants in all professional groups showed an unambitious pattern (S). Adapted interventions for the represented AVEM patterns are possible and should be utilized for maintaining mental health among general practice teams.

Incidence and impact of prosthesis-patient mismatch after transcatheter aortic valve implantation.

BACKGROUND AND AIM OF THE STUDY: The study aim was to investigate the incidence of patient-prosthesis mismatch (PPM) with new catheter valves, and its influence on the patients' clinical state. At present, few echocardiographic data are available on the incidence and impact of PPM with the CoreValve and Sapien prostheses for transcatheter aortic valve implantation (TAVI). METHODS: The reliability of effective orifice area (EOA) measurements was assured by awaiting an interval of six months after TAVI. Of 256 survivors after TAVI, 149 complete echocardiographic data sets were available for the assessment of the indexed EOA (iEOA). In total, 106 CoreValve prostheses and 43 Sapien prostheses were implanted in this high-risk cohort (mean age 81 +/- 6 years, mean logistic EuroSCORE 20 +/- 13%). RESULTS: The overall incidence of PPM (iEOA < 0.85 cm2/m2) was 61%. Patients with a larger body surface area were more likely to develop PPM (p = 0.001), while the prosthesis type, native annulus diameter, preoperative EOA, gender and prosthesis size had no influence. The mean aortic gradient was significantly higher in patients with PPM. A reduction in the left ventricular end-diastolic diameter was seen in all patients, without significant differences between groups. There were no differences in postoperative NYHA class or self-assessed health state between patients with or without PPM. CONCLUSION: PPM was common after TAVI in the presented cohort, presumably because the native calcium masses narrow the outflow area available for blood flow. As expected for low gradients, there was no impairment of left ventricular dimension regression or clinical state of the patients, even if severe PPM was present. Based on the presented data, it is assumed that PPM might be less relevant in TAVI patients.

Exploring Transfer Potentials of the IMPROVEjob Intervention for Strengthening Workplace Health Management in Micro-, Small-, and Medium-Sized Enterprises in Germany: A Qualitative Study.

Micro- and small-sized enterprises (MSE), and small- and medium-sized enterprises (SME) in Germany are often burdened with high levels of psychosocial stressors at work. The IMPROVEjob intervention was originally developed for general practice teams, and aims to promote job satisfaction and reduce psychosocial stressors in the context of workplace health management (WHM). This qualitative study identified challenges and transfer options regarding the transfer of the IMPROVEjob intervention to other MSE/SME settings. Based on previous study results, a comprehensive, qualitative inter- and transdisciplinary approach was developed and conducted between July 2020 and June 2021, also including single interviews and focus group discussion with eleven experts from MSE/SME settings. Data analysis was carried out using a rapid analysis approach. The experts discussed psychosocial topics and didactic formats of the original IMPROVEjob intervention. A lack of access to information on managing work-related psychosocial stressors and inadequate recognition of the importance of psychosocial stressors in the workplace among managers and employees, seemed to be the highest barriers regarding the transfer of the intervention into other MSE/SME settings. The transfer of the IMPROVEjob intervention to other MSE/SME settings requires an adapted intervention format, comprising targeted offers with easy access to information on managing work-related psychosocial stressors and improving WHM in MSE/SME settings.

Assessing Attitudes and Participation Regarding a Pilot COVID-19 Workplace Vaccination Program in Southern Germany Considering the Occupational Health Perspective-A Mixed Methods Study.

This mixed methods study retrospectively assessed attitudes and participation of employees, occupational health personnel, and key personnel regarding the rollout of a pilot COVID-19 workplace vaccination program in five German companies in May/June 2021 in Baden-Württemberg (Southern Germany) by combining survey data and qualitative interviews. A total of 652 employees completed a standardized questionnaire and we conducted ten interviews with occupational health personnel and key personnel with other professional backgrounds organizing the pilot workplace vaccination program. Survey data were analyzed descriptively and interviews were audio recorded, transcribed verbatim, and analyzed using qualitative content analysis. Employees participated widely in COVID-19 vaccinations at their workplaces, and most employees (n = 608; 93.8%) had a full COVID-19 immunization at the time of the survey. The main advantages of the pilot COVID-19 workplace vaccination program were seen in the flexible and time-saving vaccination offer as well as the trust in and long-standing relationship with occupational health physicians. The main disadvantage of the pilot vaccination offer was increased workload for occupational health personnel, especially during the roll-out phase of the program. The pilot COVID-19 workplace vaccination program was predominantly positively assessed, and the important role of occupational health services in managing the COVID-19 pandemic was highlighted. The main criticisms of the COVID-19 workplace vaccination program related to the high organizational and administrative burden. Findings from our study can support the development of future programs for the administration of generally recommended vaccination in the workplace setting in Germany.

Growth of Dehalococcoides mccartyi strain CBDB1 by reductive dehalogenation of brominated benzenes to benzene.

Brominated aromatics are used in many different applications but occur also naturally. Here, we demonstrate organohalide respiration and growth of Dehalococcoides mccartyi strain CBDB1 with 1,2,4-tribromobenzene, all three dibrominated benzene congeners and monobromobenzene. All bromobenzenes were fully dehalogenated to benzene. Growth yields were between 1.8 × 10(14) and 2.8 × 10(14) cells per mol of bromide released. Furthermore, a newly designed high-throughput methyl viologen-based photometric microtiter plate assay was established to determine the activity of the reductive dehalogenases in resting cell assays of strain CBDB1 with brominated aromatics as electron acceptors. Activities of 2.8-13.2 nkat per mg total cell protein (0.16-0.8 units per mg total cell protein) were calculated after cultivation of strain CBDB1 on 1,2,4-tribromobenzene. Mass spectrometric analyses and activity assays with whole cell extracts of strain CBDB1 gave strong evidence that four to six reductive dehalogenases were involved in the dehalogenation of all tested brominated benzenes, including the reductive dehalogenases CbdbA80 and CbrA.

Factors Associated with the COVID-19 Vaccination Status of Higher Education Students: Results of an Online Cross-Sectional Survey at Six Universities in Southwestern Germany.

This cross-sectional study explored factors associated with the corona virus disease 2019 (COVID-19) vaccination acceptance among higher education students in southwestern Germany. We conducted a cross-sectional online survey at six state-approved higher education institutions (HEIs) between July and November 2021. In addition to descriptive analyses, univariate as well as multivariate binary logistic regression analyses were conducted. A total of 6556 higher education students aged 18 years and older participated in our survey; 91.4% of participating students had been vaccinated against COVID-19 at least once. The factors that significantly contributed to the explanation of higher education students' vaccination status in the multivariate analysis (area under curve-AUC = 0.94) were variables on the perception of the virus SARS-CoV-2 (affective risk perception: Adjusted odds ratio-aOR = 1.2; perception of the outbreak as a media-hype: aOR = 0.8), attitudes towards personal (aOR = 0.7) and study-related (aOR = 0.8) health and safety measures to prevent transmission of SARS-CoV-2, and attitudes towards COVID-19 vaccination (preservation of own health: aOR = 1.3; confidence in vaccine safety: aOR = 1.7; supporting higher education through vaccination: aOR = 1.2; own contribution to the containment of the pandemic: aOR = 1.7). The findings target assisting HEIs in returning to face-to-face teaching after previous semesters of online teaching.

Assessing Differences in Attitudes toward Occupational Safety and Health Measures for Infection Control between Office and Assembly Line Employees during the COVID-19 Pandemic in Germany: A Cross-Sectional Analysis of Baseline Data from a Repeated Employee Survey.

In our study, we investigated possible differences across occupational groups regarding employees' perceived work-related risk of infection with SARS-CoV-2, attitudes toward technical, organisational, and personal occupational safety and health (OSH) measures for infection control, and factors associated with this attitude. We analysed baseline data (10 August to 25 October 2020) from a repeated standardised online survey distributed at a worldwide leading global supplier of technology and services in Germany. 2144 employees (32.4% women; age (mean ± SD): 44 ± 11 years) who worked predominantly remotely (n = 358), at an on-site office (n = 1451), and assembly line/manufacturing (n = 335) were included. The work-related SARS-CoV-2 risk of infection differed between office employees working remotely and on-site (mean ± SD = 2.9 ± 1.5 vs. 3.2 ± 1.5; Mann-Whitney-U-Test: W = 283,346; p < 0.002; ε2 = 0.01) and between on-site office and assembly line/manufacturing employees (3.8 ± 1.7; W = 289,174; p < 0.001; ε2 = 0.02). Attitude scores toward technical OSH-measures differed between remote and on-site office (4.3 ± 0.5 vs. 4.1 ± 0.6; W = 216,787; p < 0.001; ε2 = 0.01), and between on-site office and assembly line/manufacturing employees (3.6 ± 0.9; W = 149,881; p < 0.001; ε2 = 0.07). Findings were similar for organisational and personal measures. Affective risk perception, COVID-19-specific resilience, and information about COVID-19-related risks were associated with the employees' attitudes. To promote positive attitudes, it seems to be important to consider occupational-group-specific context factors when implementing OSH-measures for infection control.

Role of "Dehalococcoides" spp. in the anaerobic transformation of hexachlorobenzene in European rivers.

The diffuse pollution by chlorinated organic compounds in river basins is a concern, due to their potential adverse effects on human health and the environment. Organohalides, like hexachlorobenzene (HCB), are recalcitrant to aerobic microbial degradation, and "Dehalococcoides" spp. are the only known microorganisms capable of anaerobic transformation of these compounds coupled to their growth. In this study, sediments from four European rivers were studied in order to determine their HCB dechlorination capacities and the role of Dehalococcoides spp. in this process. Only a weak correlation was observed between Dehalococcoides species abundance and HCB transformation rates from different locations. In one of these locations, in the Ebro River sediment, HCB dechlorination could be linked to Dehalococcoides species growth and activity by 16S rRNA-based molecular methods. Furthermore, HCB dechlorination activity in this sediment was found over the full range of ambient temperatures that this sediment can be exposed to during different seasons throughout the year. The sediment contained several reductive dehalogenase (rdh) genes, and analysis of their transcription revealed the dominance of cbrA, previously shown to encode a trichlorobenzene reductive dehalogenase. This study investigated the role of Dehalococcoides spp. in HCB dechlorination in river sediments and evaluated if the current knowledge of rdh genes could be used to assess HCB bioremediation potential.