Influence of fumarate on interspecies electron transfer and the metabolic shift induced in Clostridium pasteurianum by Geobacter sulfurreducens.

AIMS: In previous studies, it was demonstrated that co-culturing Clostridium pasteurianum and Geobacter sulfurreducens triggers a metabolic shift in the former during glycerol fermentation. This shift, attributed to interspecies electron transfer and the exchange of other molecules, enhances the production of 1,3-propanediol at the expense of the butanol pathway. The aim of this investigation is to examine the impact of fumarate, a soluble compound usually used as an electron acceptor for G. sulfurreducens, in the metabolic shift previously described in C. pasteurianum. METHODS AND RESULTS: Experiments were conducted by adding along with glycerol, acetate, and different quantities of fumarate in co-cultures of G. sulfurreducens and C. pasteurianum. A metabolic shift was exhibited in all the co-culture conditions. This shift was more pronounced at higher fumarate concentrations. Additionally, we observed G. sulfurreducens growing even in the absence of fumarate and utilizing small amounts of this compound as an electron donor rather than an electron acceptor in the co-cultures with high fumarate addition. CONCLUSIONS: This study provided evidence that interspecies electron transfer continues to occur in the presence of a soluble electron acceptor, and the metabolic shift can be enhanced by promoting the growth of G. sulfurreducens.

Cellular Schwannoma Mimicking a Nodular Melanoma on the Sole of the Foot, an Avoidable Diagnostic Pitfall.

ABSTRACT: We report a rare case of cellular schwannoma (CS) manifesting as an ulcerated nodular lesion, mimicking spindle cell melanoma on the sole of the foot. CS, a benign variant of schwannoma, typically occurs in deep soft tissues but can rarely present cutaneously. The diagnosis of CS heavily relies on histopathological examination and immunohistochemical staining for specific markers such as SOX10 and S100. In this case, initial clinical suspicion of nodular melanoma was confirmed on biopsy, which revealed a spindle cell neoplasm positive for SOX10 and negative for melanocytic markers. Misdiagnosis of nodular melanoma was averted through complete excision. CS diagnosis demands careful consideration due to its resemblance to other spindle cell neoplasms, especially melanoma. Meticulous histopathological evaluation and immunostaining are important to differentiate CS from similar lesions, ensuring accurate diagnosis and appropriate management. This report contributes valuable insights into the diagnostic challenges and management of CS, particularly in unusual cutaneous presentations.

Characterization of the oral microbiota and the relationship of the oral microbiota with the dental and periodontal status in children and adolescents with nonsyndromic cleft lip and palate. Systematic literature review and meta-analysis.

OBJECTIVE: To identify the characteristics of the oral microbiota and the relationship of the dental caries and periodontal status in patients aged 0 to 18 years with non-syndromic cleft lip and palate (CLP). MATERIALS AND METHODS: A systematic review of the literature was carried out. Five databases were consulted, including publications in English, Spanish and Portuguese. The evaluations of the quality of the observational studies and the experimental studies were carried out with the Newcastle-Ottawa scale and CONSORT guidelines, respectively. The risk of bias of the studies was determined using Rev Manager 5.4, and 5 publications were meta-analyzed. RESULTS: The cariogenic microbiota of children and adolescents with cleft lip and palate was similar to that of children without clefts, although with higher counts of Streptococcus mutans and Lactobacillus spp. The periodontopathogenic microbiota was related to the presence of Campylobacter spp, Fusobacterium spp, Fusobacterium nucleatum, Prevotella intermedia/nigrescens, Parvimonas micra and Porphyromonas gingivalis, considered microorganisms with high pathogenic capacity. Heterogeneity was shown in relation to the microbiota and the type of fissure, presenting numerous microorganisms associated with the pre- and post-surgical condition (cheilorrhaphy and palatorrhaphy) such as Staphylococcus aureus, Streptococcus beta hemolyticus, Klebsiella pneumoniae and Klebsiella oxytoca, Moraxella catarrhalis, Candida spp, Candida albicans, Candida krusei and Candida tropicalis. The meta-analysis revealed that patients with cleft lip and palate were 2.03 times more likely to have caries than the control group (p<0.005). CONCLUSION: In the microbiota, there was a great diversity of microorganisms that can vary according to the type of fissure and surgical interventions predisposing patients to a greater probability of dental caries, it is important to take into account the technique used to describe the oral microbiota in order to be able to compare the different studies. CLINICAL RELEVANCE: Studying the microbiota and the relationship of dental caries and periodontal status in children and adolescents with cleft lip and palate can facilitate the comprehensive care of patients with these conditions.

The Known, the Unknown and the Future of the Pathophysiology of Endometriosis.

Endometriosis is one of the most common causes of chronic pelvic pain and infertility, affecting 10% of women of reproductive age. A delay of up to 9 years is estimated between the onset of symptoms and the diagnosis of endometriosis. Endometriosis is currently defined as the presence of endometrial epithelial and stromal cells at ectopic sites; however, advances in research on endometriosis have some authors believing that endometriosis should be re-defined as "a fibrotic condition in which endometrial stroma and epithelium can be identified". There are several theories on the etiology of the disease, but the origin of endometriosis remains unclear. This review addresses the role of microRNAs (miRNAs), which are naturally occurring post-transcriptional regulatory molecules, in endometriotic lesion development, the inflammatory environment within the peritoneal cavity, including the role that cytokines play during the development of the disease, and how animal models have helped in our understanding of the pathology of this enigmatic disease.

The Regulation of MicroRNA-21 by Interleukin-6 and Its Role in the Development of Fibrosis in Endometriotic Lesions.

Endometriosis is one of the most common causes of chronic pelvic pain and infertility that affects 10% of women of reproductive age. It is currently defined as the presence of endometrial epithelial and stromal cells at ectopic sites; however, advances in endometriosis research have some authors believing that endometriosis should be re-defined as "a fibrotic condition in which endometrial stroma and epithelium can be identified". microRNAs (miRNAs) are regulatory molecules that potentially play a role in endometriotic lesion development. There is evidence that suggests that miRNAs, including microRNA-21 (miR-21), participate in fibrotic processes in different organs, including the heart, kidney, liver and lungs. The objective of this study was to understand the role of miR-21 and the mechanisms that can contribute to the development of fibrosis by determining how IL-6 regulates miR-21 expression and how this miRNA regulates the transforming growth factor beta (TGF-ß) signaling pathway to promote fibrosis. We investigated the expression of miR-21 in the baboon and mouse model of endometriosis and its correlation with fibrosis. We demonstrated that inflammation and fibrosis are present at a very early stage of endometriosis and that the inflammatory environment in the peritoneal cavity, which includes interleukin 6 (IL-6), can regulate the expression of miR-21 in vitro and in vivo.

Assessment of the quality of life of patients with inflammatory bowel disease. / Evaluación de la calidad de vida de los pacientes con enfermedad inflamatoria intestinal.

INTRODUCTION: Ulcerative colitis (UC) and Crohn's disease (CD) are diseases that cause a significant impact on patients' quality of life. The aim of this study is to assess the impact of inflammatory bowel disease (IBD) on health-related quality of life (HRQoL). MATERIAL AND METHODS: Observational, descriptive, cross-sectional study, carried out at Torrecárdenas Hospital (Almería). Patients over 14 years of age diagnosed with CD or UC were included. For the assessment of HRQoL, the reduced 9-item IBDQ-9 questionnaire was used. RESULTS: 106 patients with a mean age of 44 years were included, with a female predominance. Forty-five percent of the patients in the sample had UC compared to 55% with CD. Of the patients, 69.8% were in clinical remission. The median questionnaire score was 60.8 points out of 100. Statistically significant differences were observed between sexes, with worse HRQoL for females. No differences were observed between patients with UC and CD. Differences were also detected between patients who underwent surgery and those who did not. A negative association was observed between the number of flares and the questionnaire score. CONCLUSIONS: In our study population, there is an acceptable HRQoL, with no differences observed between CD and UC. Female sex, absence of clinical remission, number of previous outbreaks, and surgery have a negative association with HRQoL.

Root-to-shoot iron partitioning in Arabidopsis requires IRON-REGULATED TRANSPORTER1 (IRT1) protein but not its iron(II) transport function.

IRON-REGULATED TRANSPORTER1 (IRT1) is the root high-affinity ferrous iron (Fe) uptake system and indispensable for the completion of the life cycle of Arabidopsis thaliana without vigorous Fe supplementation. Here we provide evidence supporting a second role of IRT1 in root-to-shoot partitioning of Fe. We show that irt1 mutants overaccumulate Fe in roots, most prominently in the cortex of the differentiation zone in irt1-2, compared to the wild type. Shoots of irt1-2 are severely Fe-deficient according to Fe content and marker transcripts, as expected. We generated irt1-2 lines producing IRT1 mutant variants carrying single amino-acid substitutions of key residues in transmembrane helices IV and V, Ser206 and His232, which are required for transport activity in yeast. Root short-term 55 Fe uptake rates were uninformative concerning IRT1-mediated transport. Overall irt1-like concentrations of the secondary substrate Mn suggested that the transgenic Arabidopsis lines also remain incapable of IRT1-mediated root Fe uptake. Yet, IRT1S206A partially complements rosette dwarfing and leaf chlorosis of irt1-2, as well as root-to-shoot Fe partitioning and gene expression defects of irt1-2, all of which are fully complemented by wild-type IRT1. Taken together, these results suggest a regulatory function for IRT1 in root-to-shoot Fe partitioning that does not require Fe transport activity of IRT1. Among the genes of which transcript levels are partially dependent on IRT1, we identify MYB DOMAIN PROTEIN10, MYB DOMAIN PROTEIN72 and NICOTIANAMINE SYNTHASE4 as candidates for effecting IRT1-dependent Fe mobilization in roots. Understanding the biological functions of IRT1 will help to improve Fe nutrition and the nutritional quality of agricultural crops.

Endoscopic management of intraluminal gastric band erosion using a laser lithotripsy probe.

Intraluminal erosion of adjustable and non adjustable gastric bands generally occurs years after placement. Different endoscopic techniques have been described for the management of bands that erode the gastric wall, using endoscopic scissors, rigid endoscopic guides wire coupled to a mechanical lithotripter or even less frequently used devices such as the Gastric Band Cutter System to cut it. We present a clinical case in which we used a lithotripsy laser probe to break the band with great effectiveness without complications.

Effect of different industrialized acid beverages on the surface roughness of flowable composite resins: in vitro study.

Flowable composite resins are materials available for restorations in pediatric dentistry. However, these materials are subject to dangerous effects in the oral environment caused by acids that deteriorate and increase their roughness. Therefore it is important to evaluate the effect of different industrialized acid beverages on the roughness of flowable composite resins. An in vitro experimental study, was done using a convenience sample of 132 discs of 5 mm diameter by 2 mm depth of four flowable materials (FF (Filtek™ Z350 XT Flowable), TNF (Tetric® N-Flow), PF (PermaFlo®) and GF (Grandio® Flow)) exposed to three beverages (CC (Coca-Cola), AJ (apple juice), and FM (fermented milk)) and incubated at 37 ºC for 0, 15 and 30 days. The roughness (average roughness (Ra) and maximum height of profile (Rz) parameters) was measured at different intervals of time with a profilometer. For the data analysis, one-way analysis of variance (one-way ANOVA) and repeated measures analysis of variance (Repeated measures ANOVA) tests were applied (p < 0.05). In the roughness test before immersion, no differences were observed within the groups, with maximum roughness values for Filtek™ Z350 XT Flowable and minimum for PermaFlo®. However, at 15 and 30 days of immersion, the groups showed significant differences depending on the immersion drink, except Grandio® Flow in apple juice and fermented milk. The flowable materials studied presented specific behaviors according to the immersion period and drink used. The Filtek™ Z350 XT Flowable showed a similar increase in surface roughness independently of the drink used. Grandio® Flow was the most stable material against surface roughness changes after beverage immersion.

Low driving voltage lithium niobate metasurface electro-optical modulator operating in free space.

A simple configuration of only λ/9 thick 2D metallic grating embedded within an electro-optic (EO) material (lithium niobate for instance) is proposed and theoretically studied to act as an EO modulator. On the one hand, this grating is used as an interdigitated comb to apply a very high and spatially periodic modification of the electrostatic field. On the other hand, the grating is designed to exhibit a Fano-like resonance in the NIR spectral range. This resonance is used to confine the electromagnetic field inside the EO material leading to an intrinsic enhancement of the EO effect. Extensive numerical simulations are performed to optimize the geometry in agreement with technological fabrication constraints. We achieved a local field factor of 24.5 leading to a local index modification Δn as large as 1 for 1 V applied voltage. This allows a modulation sensitivity of 14.35 nm/V (2000 times larger than state of the art) together with a resonance depth of 60% and a driving voltage of only 75 mV opening the way to the fabrication of ultra-thin low driving voltage EO devices.

Arabidopsis thaliana Zn2+-efflux ATPases HMA2 and HMA4 are required for resistance to the necrotrophic fungus Plectosphaerella cucumerina BMM.

Zinc is an essential nutrient at low concentrations, but toxic at slightly higher ones. It has been proposed that hyperaccumulator plants may use the excess zinc to fend off pathogens and herbivores. However, there is little evidence of a similar response in other plants. Here we show that Arabidopsis thaliana leaves inoculated with the necrotrophic fungus Plectosphaerella cucumerina BMM (PcBMM) accumulate zinc and manganese at the infection site. Zinc accumulation did not occur in a double mutant in the zinc transporters HEAVY METAL ATPASE2 and HEAVY METAL ATPASE4 (HMA2 and HMA4), which has reduced zinc translocation from roots to shoots. Consistent with a role in plant immunity, expression of HMA2 and HMA4 was up-regulated upon PcBMM inoculation, and hma2hma4 mutants were more susceptible to PcBMM infection. This phenotype was rescued upon zinc supplementation. The increased susceptibility to PcBMM infection was not due to the diminished expression of genes involved in the salicylic acid, ethylene, or jasmonate pathways since they were constitutively up-regulated in hma2hma4 plants. Our data indicate a role of zinc in resistance to PcBMM in plants containing ordinary levels of zinc. This layer of immunity runs in parallel to the already characterized defence pathways, and its removal has a direct effect on resistance to pathogens.

Mechanisms underlying Clostridium pasteurianum's metabolic shift when grown with Geobacter sulfurreducens.

Recently, a study showed that glycerol fermentation by Clostridium pasteurianum could be metabolically redirected when the electroactive bacterium Geobacter sulfurreducens was added in the culture. It was assumed that this metabolic shift of the fermentative species resulted from an interspecies electron transfer. The aim of this study was to find out the mechanisms used for this interaction and how they affect the metabolism of C. pasteurianum. To get insights into the mechanisms involved, several coculture setups and RNA sequencing with differential expression analysis were performed. As a result, a putative interaction model was proposed: G. sulfurreducens produces cobamide molecules that possibly modify C. pasteurianum metabolic pathway at the key enzyme glycerol dehydratase, and affect its vanadium nitrogenase expression. In addition, the results suggested that G. sulfurreducens' electrons could enter C. pasteurianum through its transmembrane flavin-bound polyferredoxin and cellular cytochrome b5-rubredoxin interplay, putatively reinforcing the metabolic shift. Unravelling the mechanisms behind the interaction between fermentative and electroactive bacteria helps to better understand the role of bacterial interactions in fermentation setups. KEY POINTS: • C. pasteurianum-G. sulfurreducens interaction inducing a metabolic shift is mediated • C. pasteurianum's metabolic shift in coculture might be induced by cobamides • Electrons possibly enter C. pasteurianum through a multiflavin polyferredoxin.

Measuring Mechanical Properties of Spastic Muscles After Stroke. Does Muscle Position During Assessment Really Matter?

OBJECTIVE: To investigate the influence of muscle position (relaxed vs stretched) on muscle mechanical properties and the ability of myotonometry to detect differences between sides, groups, and sites of testing in patients with stroke. We also analyzed the association between myotonometry and clinical measures of spasticity. DESIGN: Cross-sectional study. SETTING: Outpatient rehabilitation units including private and public centers. PARTICIPANTS: Seventy-one participants (20 subacute stroke, 20 chronic stroke, 31 controls) were recruited (N=71). INTERVENTION: Muscle mechanical properties were measured bilaterally with a MyotonPRO at muscle belly and musculotendinous sites during 2 protocols (muscle relaxed or in maximal bearable stretched position). MAIN OUTCOME MEASURES: Muscle tone and stiffness of the biceps brachii and gastrocnemius. Poststroke spasticity was evaluated with the Modified Tardieu Scale (MTS). A mixed-model analysis of variance was used to detect differences in the outcome measures. RESULTS: The analysis of variance showed a significant effect of muscle position on muscle mechanical properties (higher tone and stiffness with the muscle assessed in stretched position). Measurements with the stretched muscle could help discriminate between spastic and nonspastic sides, but only at the biceps brachii. Overall, there was a significant increase in tone and stiffness in the chronic stroke group and in myotendinous sites compared with muscle belly sites (all, P<.05). No correlations were found between myotonometry and the MTS. CONCLUSIONS: Myotonometry assessment of mechanical properties with the muscle stretched improves the ability of myotonometry to discriminate between sides in patients after stroke and between people with and without stroke.

The Disease-Modifying Role of Taurine and Its Therapeutic Potential in Coronavirus Disease 2019 (COVID-19).

Taurine is an amino sulfonic acid that is implicated in numerous physiological functions, including the regulation of oxidative stress, which plays an important role in coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), together with other pathophysiological processes. The recent finding of decreased serum taurine levels in SARS-CoV-2-infected patients, in tandem with its potential modulatory role in COVID-19 due to its antiviral, antioxidant, anti-inflammatory, and vascular-related effects, provides a rationale for considering taurine as a beneficial supplement in patients suffering from COVID-19. Here, we reviewed the potential disease-modifying effects of taurine and combined these with the current knowledge on COVID-19 to clarify the potential role of taurine in this respiratory disease.

Association between sociodemographic characteristics and level of knowledge about oral cancer among Mexican dental health professionals: a cross-sectional online survey.

BACKGROUND: A good level of knowledge in dentists is crucial for an early diagnosis of oral cancer (OC). In Latin America there are a few studies of OC knowledge among dentist, those has been performed in Brazil, Colombia, and Chile, and their results showed low level of OC knowledge. On the other hand, there is no publication in which the level of knowledge of dentists in Mexico has been addressed. Therefore, this study aimed to assess knowledge of OC and to determine the association of the level of knowledge with sociodemographic characteristics among dentists in Mexico. METHODS: A cross-sectional online survey was designed to obtain information via questionnaire. The questionnaire was developed in the Spanish language, and the content validity was determined. The study was conducted among Mexican dentists with a 23-item questionnaire that was designed to be anonymous. The sample size was calculated using the finite population formula. Based on the responses, the level of knowledge of OC was categorized as very low, low, regular, good, or excellent. Additionally, the association between sociodemographic characteristics and the level of knowledge about OC was evaluated. RESULTS: This research was conducted on a sample of 387 dentists. Most of the respondents were general dentists and worked in urban zones. The majority of dentists lacked a specialty (76.7%). Additionally, most of the respondents were students (44.2%). The level of knowledge of the participants was between regular and good (77.8%). On the other hand, concerning self-evaluation, most of the participants considered their knowledge of OC to be regular (50.6%). In addition, there was no association between sociodemographic characteristics and knowledge about OC. CONCLUSIONS: This research identified some weaknesses in most Mexican dentists' knowledge of OC.

Evaluation of Effective Class-Balancing Techniques for CNN-Based Assessment of Aphanomyces Root Rot Resistance in Pea (Pisum sativum L.).

Aphanomyces root rot (ARR) is a devastating disease that affects the production of pea. The plants are prone to infection at any growth stage, and there are no chemical or cultural controls. Thus, the development of resistant pea cultivars is important. Phenomics technologies to support the selection of resistant cultivars through phenotyping can be valuable. One such approach is to couple imaging technologies with deep learning algorithms that are considered efficient for the assessment of disease resistance across a large number of plant genotypes. In this study, the resistance to ARR was evaluated through a CNN-based assessment of pea root images. The proposed model, DeepARRNet, was designed to classify the pea root images into three classes based on ARR severity scores, namely, resistant, intermediate, and susceptible classes. The dataset consisted of 1581 pea root images with a skewed distribution. Hence, three effective data-balancing techniques were identified to solve the prevalent problem of unbalanced datasets. Random oversampling with image transformations, generative adversarial network (GAN)-based image synthesis, and loss function with class-weighted ratio were implemented during the training process. The result indicated that the classification F1-score was 0.92 ± 0.03 when GAN-synthesized images were added, 0.91 ± 0.04 for random resampling, and 0.88 ± 0.05 when class-weighted loss function was implemented, which was higher than when an unbalanced dataset without these techniques were used (0.83 ± 0.03). The systematic approaches evaluated in this study can be applied to other image-based phenotyping datasets, which can aid the development of deep-learning models with improved performance.

KASP: a genotyping method to rapid identification of resistance in Plasmodium falciparum.

BACKGROUND: The emergence and spread of anti-malarial resistance continues to hinder malaria control. Plasmodium falciparum, the species that causes most human malaria cases and most deaths, has shown resistance to almost all known anti-malarials. This anti-malarial resistance arises from the development and subsequent expansion of Single Nucleotide Polymorphisms (SNPs) in specific parasite genes. A quick and cheap tool for the detection of drug resistance can be crucial and very useful for use in hospitals and in malaria control programmes. It has been demonstrated in different contexts that genotyping by Kompetitive Allele Specific PCR (KASP), is a simple, fast and economical method that allows a high-precision biallelic characterization of SNPs, hence its possible utility in the study of resistance in P. falciparum. METHODS: Three SNPs involved in most cases of resistance to the most widespread anti-malarial treatments have been analysed by PCR plus sequencing and by KASP (C580Y of the Kelch13 gene, Y86N of the Pfmdr1 gene and M133I of the Pfcytb gene). A total of 113 P. falciparum positive samples and 24 negative samples, previously analysed by PCR and sequencing, were selected for this assay. Likewise, the samples were genotyped for the MSP-1 and MSP-2 genes, and the Multiplicity of Infection (MOI) and parasitaemia were measured to observe their possible influence on the KASP method. RESULTS: The KASP results showed the same expected mutations and wild type genotypes as the reference method, with few exceptions that correlated with very low parasitaemia samples. In addition, two cases of heterozygotes that had not been detected by sequencing were found. No correlation was found between the MOI or parasitaemia and the KASP values of the sample. The reproducibility of the technique shows no oscillations between repetitions in any of the three SNPs analysed. CONCLUSIONS: The KASP assays developed in this study were efficient and versatile for the determination of the Plasmodium genotypes related to resistance. The method is simple, fast, reproducible with low cost in personnel, material and equipment and scalable, being able to core KASP arrays, including numerous SNPs, to complete the main pattern of mutations associated to P. falciparum resistance.

A Data-Driven Approach to Physical Fatigue Management Using Wearable Sensors to Classify Four Diagnostic Fatigue States.

Physical exercise contributes to the success of rehabilitation programs and rehabilitation processes assisted through social robots. However, the amount and intensity of exercise needed to obtain positive results are unknown. Several considerations must be kept in mind for its implementation in rehabilitation, as monitoring of patients' intensity, which is essential to avoid extreme fatigue conditions, may cause physical and physiological complications. The use of machine learning models has been implemented in fatigue management, but is limited in practice due to the lack of understanding of how an individual's performance deteriorates with fatigue; this can vary based on physical exercise, environment, and the individual's characteristics. As a first step, this paper lays the foundation for a data analytic approach to managing fatigue in walking tasks. The proposed framework establishes the criteria for a feature and machine learning algorithm selection for fatigue management, classifying four fatigue diagnoses states. Based on the proposed framework and the classifier implemented, the random forest model presented the best performance with an average accuracy of ≥98% and F-score of ≥93%. This model was comprised of ≤16 features. In addition, the prediction performance was analyzed by limiting the sensors used from four IMUs to two or even one IMU with an overall performance of ≥88%.

Revealing photonic symmetry-protected modes by the finite-difference-time-domain method.

This Letter is devoted to pointing out a specific feature of the finite-difference-time-domain (FDTD) method through the study of nano-structures supporting geometrical symmetry-protected modes that cannot be excited at certain conditions of illumination. The spatial discretization performed in the FDTD algorithm naturally leads to breaking this symmetry and allows the excitation of these modes. The quality factors of the corresponding resonances are then directly linked to the degree of symmetry breaking, i.e., the spatial grid dimension, even though the convergence criteria of the FDTD are fulfilled. This finding shows that the FDTD must be handled with great care and, more importantly, that very huge quality-factor resonances can be achieved at the cost of nanometer-scale mastered fabrication processes.

Desulfobotulus mexicanus sp. nov., a novel sulfate-reducing bacterium isolated from the sediment of an alkaline crater lake in Mexico.

A novel Gram-negative, non-spore-forming, vibrio-shaped, anaerobic, alkaliphilic, sulfate-reducing bacterium, designated strain PAR22NT, was isolated from sediment samples collected at an alkaline crater lake in Guanajuato (Mexico). Strain PAR22NT grew at temperatures between 15 and 37 °C (optimum, 32 °C), at pH between pH 8.3 and 10.1 (optimum, pH 9.0-9.6), and in the presence of NaCl up to 10 %. Pyruvate, 2-methylbutyrate and fatty acids (4-18 carbon atoms) were used as electron donors in the presence of sulfate as a terminal electron acceptor and were incompletely oxidized to acetate and CO2. Besides sulfate, both sulfite and elemental sulfur were also used as terminal electron acceptors and were reduced to sulfide. The predominant fatty acids were summed feature 10 (C18 : 1 ω7c and/or C18 : 1 ω9t and/or C18 : 1 ω12t), C18 : 1 ω9c and C16 : 0. The genome size of strain PAR22NT was 3.8 Mb including 3391 predicted genes. The genomic DNA G+C content was 49.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that it belongs to the genus Desulfobotulus within the class Deltaproteobacteria. Its closest phylogenetic relatives are Desulfobotulus alkaliphilus (98.4 % similarity) and Desulfobotulus sapovorans (97.9 % similarity). Based on phylogenetic, phenotypic and chemotaxonomic characteristics, we propose that the isolate represents a novel species of the genus Desulfobotulus with the name Desulfobotulus mexicanus sp. nov. The type strain is PAR22NT (=DSM 105758T=JCM 32146T).