RESUMEN

Clostridioides difficile is an emerging One Health pathogen and a common etiologic agent of diarrhea, both in healthcare settings and the community. This bacterial species is highly diverse, and its global population has been classified in eight clades by multilocus sequence typing (MLST). The C. difficile MLST Clade 2 includes the NAP1/RT027/ST01 strain, which is highly recognized due to its epidemicity and association with severe disease presentation and mortality. By contrast, the remaining 83 sequence types (STs) that compose this clade have received much less attention. In response to this shortcoming, we reviewed articles published in English between 1999 and 2020 and collected information for 27 Clade 2 STs, with an emphasis on STs 01, 67, 41 and 188/231/365. Our analysis provides evidence of large phenotypic differences that preclude support of the rather widespread notion that ST01 and Clade 2 strains are "hypervirulent". Moreover, it revealed a profound lack of (meta)data for nearly 70% of the Clade 2 STs that have been identified in surveillance efforts. Targeted studies aiming to relate wet-lab and bioinformatics results to patient and clinical parameters should be performed to gain a more in-depth insight into the biology of this intriguing group of C. difficile isolates.

Asunto(s)

Infecciones por Clostridium/epidemiología , Infecciones por Clostridium/fisiopatología , Clostridium/clasificación , Clostridium/genética , Virulencia/genética , Técnicas de Tipificación Bacteriana , Variación Genética , Genotipo , Humanos , Epidemiología Molecular , Filogenia

RESUMEN

Botulinum neurotoxin-producing clostridia are diverse in the types of toxins they produce as well as in their overall genomic composition. They are globally distributed, with prevalent species and toxin types found within distinct geographic regions, but related strains containing the same toxin types may also be located on distinct continents. The mechanisms behind the spread of these bacteria and the independent movements of their bont genes may be understood through examination of their genetic backgrounds. The generation of 15 complete genomic sequences from bacteria isolated in Argentina, Australia, and Africa allows for a thorough examination of genome features, including overall relationships, bont gene cluster locations and arrangements, and plasmid comparisons, in bacteria isolated from various areas in the southern hemisphere. Insights gained from these examinations provide an understanding of the mechanisms behind the independent movements of these elements among distinct species.

Asunto(s)

Toxinas Botulínicas/genética , Clostridium/genética , África , Argentina , Australia , Toxinas Botulínicas/biosíntesis , Clostridium/clasificación , Clostridium/metabolismo , Genoma Bacteriano , Genómica , Filogenia

RESUMEN

The aim of this study was to understand how the microbial community adapted to changes, including a pH perturbation, occurring during the start-up and operation processes in a full-scale methanogenic UASB reactor designed to treat dairy wastewater. The reactor performance, prokaryotic community, and lipid degradation capacity were monitored over a 9-month period. The methanogenic community was studied by mcrA/mrtA gene copy-number quantification and methanogenic activity tests. A diverse prokaryotic community characterized the seeding sludge as assessed by sequencing the V4 region of the 16S rRNA gene. As the feeding began, the bacterial community was dominated by Firmicutes, Synergistetes, and Proteobacteria phyla. After an accidental pH increase that affected the microbial community structure, a sharp increase in the relative abundance of Clostridia and a decrease in the mcrA/mrtA gene copy number and methanogenic activity were observed. After a recovery period, the microbial population regained diversity and methanogenic activity. Alkaline shocks are likely to happen in dairy wastewater treatment because of the caustic soda usage. In this work, the plasticity of the prokaryotic community was key to surviving changes to the external environment and supporting biogas production in the reactor.

Asunto(s)

Reactores Biológicos/microbiología , Aguas del Alcantarillado/microbiología , Eliminación de Residuos Líquidos , Microbiología del Agua , Purificación del Agua , Anaerobiosis , Archaea/metabolismo , Bacterias Anaerobias/clasificación , Biocombustibles , Clostridium/clasificación , Industria Lechera , Euryarchaeota/metabolismo , Firmicutes/clasificación , Concentración de Iones de Hidrógeno , Metano/metabolismo , Microbiota , Proteobacteria/clasificación , ARN Ribosómico 16S/genética , Aguas Residuales

RESUMEN

Abstract The aim of this study was to identify different Clostridium spp. isolated from currency notes from the Ha’il region of Saudi Arabia in September 2014 using MALDI–TOF-MS. Clostridium spp. were identified by Bruker MALDI–TOF-MS and compared with VITEK 2. The confirmation of the presence of different Clostridium spp. was performed by determining the sequence of the 16S ribosomal RNA gene. In this study, 144 Clostridium spp. were isolated. Among these specimens, MALDI–TOF-MS could identify 88.8% (128/144) of the isolates to the species level and 92.3% (133/144) to the genus level, whereas, VITEK 2 identified 77.7% of the (112/144) isolates. The correct identification of the 144 isolates was performed by sequence analysis of the 500 bp 16S rRNA gene. The most common Clostridium spp. identified were Clostridium perfringens (67.36%), Clostridium subterminale (14.58%), Clostridium sordellii (9%) and Clostridium sporogenes (9%). The results of this study demonstrate that MALDI–TOF-MS is a rapid, accurate and user friendly technique for the identification of Clostridium spp. Additionally, MALDI–TOF-MS has advantages over VITEK 2 in the identification of fastidious micro-organisms, such as Clostridium spp. Incorporating this technique into routine microbiology would lead to more successful and rapid identification of pathogenic and difficult to identify micro-organisms.

Asunto(s)

Humanos , Clostridium/aislamiento & purificación , Clostridium/química , Espectrometría de Masas en Tándem/métodos , Arabia Saudita , Técnicas de Tipificación Bacteriana/métodos , Clostridium/clasificación , Clostridium/genética , Infecciones por Clostridium/microbiología , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos

RESUMEN

The aim of this study was to identify different Clostridium spp. isolated from currency notes from the Hail region of Saudi Arabia in September 2014 using MALDITOF-MS. Clostridium spp. were identified by Bruker MALDITOF-MS and compared with VITEK 2. The confirmation of the presence of different Clostridium spp. was performed by determining the sequence of the 16S ribosomal RNA gene. In this study, 144 Clostridium spp. were isolated. Among these specimens, MALDITOF-MS could identify 88.8% (128/144) of the isolates to the species level and 92.3% (133/144) to the genus level, whereas, VITEK 2 identified 77.7% of the (112/144) isolates. The correct identification of the 144 isolates was performed by sequence analysis of the 500 bp 16S rRNA gene. The most common Clostridium spp. identified were Clostridium perfringens (67.36%), Clostridium subterminale (14.58%), Clostridium sordellii (9%) and Clostridium sporogenes (9%). The results of this study demonstrate that MALDITOF-MS is a rapid, accurate and user friendly technique for the identification of Clostridium spp. Additionally, MALDITOF-MS has advantages over VITEK 2 in the identification of fastidious micro-organisms, such as Clostridium spp. Incorporating this technique into routine microbiology would lead to more successful and rapid identification of pathogenic and difficult to identify micro-organisms.(AU)

Asunto(s)

Análisis Espectral , Clostridium/aislamiento & purificación , Clostridium/clasificación

RESUMEN

The aim of this study was to identify different Clostridium spp. isolated from currency notes from the Ha'il region of Saudi Arabia in September 2014 using MALDI-TOF-MS. Clostridium spp. were identified by Bruker MALDI-TOF-MS and compared with VITEK 2. The confirmation of the presence of different Clostridium spp. was performed by determining the sequence of the 16S ribosomal RNA gene. In this study, 144 Clostridium spp. were isolated. Among these specimens, MALDI-TOF-MS could identify 88.8% (128/144) of the isolates to the species level and 92.3% (133/144) to the genus level, whereas, VITEK 2 identified 77.7% of the (112/144) isolates. The correct identification of the 144 isolates was performed by sequence analysis of the 500bp 16S rRNA gene. The most common Clostridium spp. identified were Clostridium perfringens (67.36%), Clostridium subterminale (14.58%), Clostridium sordellii (9%) and Clostridium sporogenes (9%). The results of this study demonstrate that MALDI-TOF-MS is a rapid, accurate and user friendly technique for the identification of Clostridium spp. Additionally, MALDI-TOF-MS has advantages over VITEK 2 in the identification of fastidious micro-organisms, such as Clostridium spp. Incorporating this technique into routine microbiology would lead to more successful and rapid identification of pathogenic and difficult to identify micro-organisms.

Asunto(s)

Clostridium/química , Clostridium/aislamiento & purificación , Espectrometría de Masas en Tándem/métodos , Técnicas de Tipificación Bacteriana/métodos , Clostridium/clasificación , Clostridium/genética , Infecciones por Clostridium/microbiología , Humanos , Arabia Saudita , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos

RESUMEN

To provide new insight into the dark fermentation process, a multi-lateral study was performed to study the microbiology of 20 different lab-scale bioreactors operated in four different countries (Brazil, Chile, Mexico, and Uruguay). Samples (29) were collected from bioreactors with different configurations, operation conditions, and performances. The microbial communities were analyzed using 16S rRNA genes 454 pyrosequencing. The results showed notably uneven communities with a high predominance of a particular genus. The phylum Firmicutes predominated in most of the samples, but the phyla Thermotogae or Proteobacteria dominated in a few samples. Genera from three physiological groups were detected: high-yield hydrogen producers (Clostridium, Kosmotoga, Enterobacter), fermenters with low-hydrogen yield (mostly from Veillonelaceae), and competitors (Lactobacillus). Inocula, reactor configurations, and substrates influence the microbial communities. This is the first joint effort that evaluates hydrogen-producing reactors and operational conditions from different countries and contributes to understand the dark fermentation process.

Asunto(s)

Reactores Biológicos/normas , Fermentación , Hidrógeno/metabolismo , Consorcios Microbianos/genética , ARN Ribosómico 16S/genética , Anaerobiosis , Clostridium/clasificación , Clostridium/genética , Clostridium/metabolismo , Enterobacter/clasificación , Enterobacter/genética , Enterobacter/metabolismo , Firmicutes/clasificación , Firmicutes/genética , Firmicutes/metabolismo , Secuenciación de Nucleótidos de Alto Rendimiento , Lactobacillus/clasificación , Lactobacillus/genética , Lactobacillus/metabolismo , América Latina , Proteobacteria/clasificación , Proteobacteria/genética , Proteobacteria/metabolismo , Thermotoga maritima/clasificación , Thermotoga maritima/genética , Thermotoga maritima/metabolismo , Veillonellaceae/clasificación , Veillonellaceae/genética , Veillonellaceae/metabolismo

RESUMEN

A strictly anaerobic Gram-stain positive, spore-forming, rod-shaped bacterium designated NE08V(T), was isolated from a fecal sample of an individual residing in a remote Amazonian community in Peru. Phylogenetic analysis based on the 16S rRNA gene sequence showed the organism belonged to the genus Clostridium and is most closely related to Clostridium vulturis (97.4% sequence similarity) and was further characterized using biochemical and chemotaxonomic methods. The major cellular fatty acids were anteiso C13:0 and C16:0 with a genomic DNA G + C content of 31.6 mol%. Fermentation products during growth with PYG were acetate and butyrate. Based on phylogenetic, phenotypic and chemotaxonomic information, strain NE08V was identified as representing a novel species of the genus Clostridium, for which the name Clostridium amazonense sp. nov. is proposed. The type strain is NE08V(T) (DSM 23598(T) = CCUG 59712(T)).

Asunto(s)

Clostridium/clasificación , Clostridium/aislamiento & purificación , Heces/microbiología , Técnicas de Tipificación Bacteriana , Composición de Base , Análisis por Conglomerados , Citosol/química , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Ácidos Grasos/análisis , Humanos , Datos de Secuencia Molecular , Perú , Filogenia , Grupos de Población , ARN Ribosómico 16S/genética , Población Rural , Análisis de Secuencia de ADN

RESUMEN

The objective of this study was to describe the first report involving a case of equine acute myonecrosis caused by C. novyi type A with an emphasis on clinical signs, the pathological and bacteriological analysis, and molecular identification of the microorganisms as the key of the definitive diagnosis.

Asunto(s)

Infecciones por Clostridium/veterinaria , Clostridium/clasificación , Clostridium/aislamiento & purificación , Enfermedades de los Caballos/diagnóstico , Enfermedades de los Caballos/patología , Miositis/veterinaria , Necrosis/veterinaria , Animales , Infecciones por Clostridium/diagnóstico , Infecciones por Clostridium/microbiología , Infecciones por Clostridium/patología , Análisis por Conglomerados , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Histocitoquímica , Enfermedades de los Caballos/microbiología , Caballos , Miositis/diagnóstico , Miositis/microbiología , Miositis/patología , Necrosis/diagnóstico , Necrosis/microbiología , Necrosis/patología , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN

RESUMEN

The objective of this study was to describe the first report involving a case of equine acute myonecrosis caused by C. novyi type A with an emphasis on clinical signs, the pathological and bacteriological analysis, and molecular identification of the microorganisms as the key of the definitive diagnosis.

Asunto(s)

Animales , Infecciones por Clostridium/veterinaria , Clostridium/clasificación , Clostridium/aislamiento & purificación , Enfermedades de los Caballos/diagnóstico , Enfermedades de los Caballos/patología , Miositis/veterinaria , Necrosis/veterinaria , Análisis por Conglomerados , Infecciones por Clostridium/diagnóstico , Infecciones por Clostridium/microbiología , Infecciones por Clostridium/patología , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Histocitoquímica , Caballos , Enfermedades de los Caballos/microbiología , Miositis/diagnóstico , Miositis/microbiología , Miositis/patología , Necrosis/diagnóstico , Necrosis/microbiología , Necrosis/patología , Filogenia , /genética , Análisis de Secuencia de ADN

RESUMEN

The objective of this study was to describe the first report involving a case of equine acute myonecrosis caused by C. novyi type A with an emphasis on clinical signs, the pathological and bacteriological analysis, and molecular identification of the microorganisms as the key of the definitive diagnosis.(AU)

Asunto(s)

Animales , Infecciones por Clostridium/veterinaria , Clostridium/clasificación , Clostridium/aislamiento & purificación , Enfermedades de los Caballos/diagnóstico , Enfermedades de los Caballos/patología , Miositis/veterinaria , Necrosis/veterinaria , Análisis por Conglomerados , Infecciones por Clostridium/microbiología , Infecciones por Clostridium/patología , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Histocitoquímica , Enfermedades de los Caballos/microbiología , Miositis/diagnóstico , Miositis/microbiología , Necrosis/diagnóstico , Necrosis/microbiología , Necrosis/patología , Filogenia , Análisis de Secuencia de ADN

RESUMEN

UNLABELLED: This study correlated the composition of the spoilage bacterial flora with the main gaseous and volatile organic compounds (VOCs) found in the package headspace of spoiled, chilled, vacuum-packed meat. Fifteen chilled, vacuum-packed beef samples, suffering from blown pack spoilage, were studied using 16S rRNA clone sequencing. More than 50% of the bacteria were identified as lactic acid bacteria (LAB), followed by clostridia and enterobacteria. Fifty-one volatile compounds were detected in the spoiled samples. Although the major spoilage compounds were identified as alcohols and aldehydes, CO2 was identified as the major gas in the spoiled samples by headspace technique. Different species of bacteria contribute to different volatile compounds during meat spoilage. LAB played an important role in blown pack deterioration of the Brazilian beef studied. SIGNIFICANCE AND IMPACT OF THE STUDY: The data generated by this study provided useful information to correlate the microbial contamination of Enterobacteriaceae, lactic acid bacteria and Clostridium with the VOC and gaseous compound production to define, in a faster manner, not only the type of contamination, but also to prevent it.

Asunto(s)

Contaminación de Alimentos/análisis , Embalaje de Alimentos , Gases/análisis , Carne/microbiología , Compuestos Orgánicos Volátiles/análisis , Animales , Técnicas de Tipificación Bacteriana , Secuencia de Bases , Brasil , Bovinos , Clostridium/clasificación , Clostridium/genética , Clostridium/aislamiento & purificación , ADN Bacteriano/genética , Enterobacteriaceae/clasificación , Enterobacteriaceae/genética , Enterobacteriaceae/aislamiento & purificación , Gases/metabolismo , Lactobacillales/clasificación , Lactobacillales/genética , Lactobacillales/aislamiento & purificación , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Compuestos Orgánicos Volátiles/metabolismo

RESUMEN

INTRODUCTION: The characterization of microbial communities infecting the endodontic system in each clinical condition may help on the establishment of a correct prognosis and distinct strategies of treatment. The purpose of this study was to determine the bacterial diversity in primary endodontic infections by 16S ribosomal-RNA (rRNA) sequence analysis. METHODS: Samples from root canals of untreated asymptomatic teeth (n = 12) exhibiting periapical lesions were obtained, 16S rRNA bacterial genomic libraries were constructed and sequenced, and bacterial diversity was estimated. RESULTS: A total of 489 clones were analyzed (mean, 40.7 ± 8.0 clones per sample). Seventy phylotypes were identified of which six were novel phylotypes belonging to the family Ruminococcaceae. The mean number of taxa per canal was 10.0, ranging from 3 to 21 per sample; 65.7% of the cloned sequences represented phylotypes for which no cultivated isolates have been reported. The most prevalent taxa were Atopobium rimae (50.0%), Dialister invisus, Prevotella oris, Pseudoramibacter alactolyticus, and Tannerella forsythia (33.3%). CONCLUSIONS: Although several key species predominate in endodontic samples of asymptomatic cases with periapical lesions, the primary endodontic infection is characterized by a wide bacterial diversity, which is mostly represented by members of the phylum Firmicutes belonging to the class Clostridia followed by the phylum Bacteroidetes.

Asunto(s)

Bacterias/clasificación , Cavidad Pulpar/microbiología , Enfermedades Periapicales/microbiología , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Adolescente , Adulto , Bacterias/genética , Bacterias/aislamiento & purificación , Bacteroidetes/clasificación , Bacteroidetes/genética , Bacteroidetes/aislamiento & purificación , Clostridium/clasificación , Clostridium/genética , Clostridium/aislamiento & purificación , Biblioteca Genómica , Humanos , Consorcios Microbianos/genética , Persona de Mediana Edad , ARN Bacteriano/análisis , ARN Ribosómico 16S/análisis , Ruminococcus/clasificación , Ruminococcus/genética , Ruminococcus/aislamiento & purificación , Análisis de Secuencia de ARN/métodos , Adulto Joven

RESUMEN

Strain ILE-2(T) was isolated from an upflow anaerobic sludge bed reactor treating brewery wastewater. The motile, non-sporulating, slightly curved cells (2-4 x 0.1 microm) stained Gram-negative and grew optimally at 42 degrees C and pH 7.1 with 0.5 % NaCl. The strain required yeast extract for growth and fermented Casamino acids, peptone, isoleucine, arginine, lysine, alanine, valine, glutamate, histidine, glutamine, methionine, malate, fumarate, glycerol and pyruvate to acetate, propionate and minor amounts of branched-chain fatty acids. Carbohydrates, formate, acetate, propionate, butyrate, isovalerate, methanol, ethanol, 1-propanol, butanol, lactate, succinate, starch, casein, gelatin, xylan and a number of other amino acids were not utilized. The DNA G+C content of strain ILE-2(T) was 52.7 mol%. 16S rRNA gene sequence analysis revealed that ILE-2(T) was distantly related to members of the genera Aminobacterium (83 % similarity) and Aminomonas (85 % similarity) in the family Syntrophomonadaceae, order Clostridiales, phylum Firmicutes. On the basis of the results of our polyphasic analysis, strain ILE-2(T) represents a novel species and genus within the family Syntrophomonadaceae, for which the name Aminiphilus circumscriptus gen. nov., sp. nov. is proposed. The type strain of Aminiphilus circumscriptus is ILE-2(T) (=DSM 16581(T) =JCM 14039(T)).

Asunto(s)

Clostridium/clasificación , Clostridium/metabolismo , Aguas del Alcantarillado/microbiología , Aminoácidos/metabolismo , Anaerobiosis , Reactores Biológicos , Clostridium/genética , Clostridium/aislamiento & purificación , ADN Bacteriano , ADN Ribosómico/genética , Fermentación , Residuos Industriales , Datos de Secuencia Molecular , Filogenia , ARN Ribosómico 16S/genética

RESUMEN

Amplified Fragment Length Polymorphism (AFLP) analysis was used for characterising 13 native Colombian Clostridium spp strains. The DNA extraction method was optimised and the use of cetyl trimethyl ammonium bromide (CTAB) and sodium chloride (NaCl) was incorporated. All strains could be typed in these conditions. The AFLP profiles obtained were submitted to multivariate analysis and compared with previous pulsed field gel electrophoresis (PFGE) results. The results suggested that the set of native strains could correspond to two new species different to those having been described to date. It is proposed that DNA-DNA hybridisation analysis should be done to produce complementary information for describing the new species.

Asunto(s)

Clostridium/clasificación , Dermatoglifia del ADN/métodos , Clasificación/métodos , Clostridium/genética , Colombia , ADN Bacteriano/genética , ADN Bacteriano/aislamiento & purificación , Análisis Multivariante , Polimorfismo Genético

RESUMEN

Species of Clostridium are widely distributed in the environment, inhabiting both human and animal gastrointestinal tracts. Clostridium difficile is an important pathogen associated with outbreaks of pseudomembranous colitis and other intestinal disorders, such as diarrhea. In this study, the prevalence of Clostridium spp. and C. difficile, from hospitalized children with acute diarrhea, was examined. These children were admitted to 3 different hospitals for over 12 months. Eighteen (20%) and 19 (21%) stool specimens from children with (90) and without (91) diarrhea respectively, were positive to clostridia. Only 10 C. difficile strains were detected in 5.5% of the stool samples of children with diarrhea. None healthy children (without diarrhea) harbored C. difficile. From these 10 C. difficile, 9 were considered as toxigenic and genotyped as tcdA+/tcdB+ or tcdA-/tcdB+, and 1 strain as nontoxigenic (tcdA-/tdcB-). They were detected by the citotoxicity on VERO cells and by the multiplex-polymerase chain reaction. Thirty clinical fecal extracts produced minor alterations on VERO cells. The presence of C. difficile as a probable agent of acute diarrhea is suggested in several countries, but in this study, the presence of these organisms was not significant. More studies will be necessary to evaluate the role of clostridia or C. difficile in diarrhoeal processes in children.

Asunto(s)

Infecciones por Clostridium/microbiología , Clostridium/aislamiento & purificación , Diarrea/microbiología , Enfermedad Aguda , Animales , Brasil/epidemiología , Estudios de Casos y Controles , Preescolar , Clostridioides difficile/genética , Clostridioides difficile/aislamiento & purificación , Clostridium/clasificación , Clostridium/genética , Infecciones por Clostridium/epidemiología , Heces/microbiología , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Prevalencia , Toxinas Shiga/análisis

RESUMEN

Botulism, well known for centuries, continues to preoccupy the Public Health authorities, food and agricultural industries. In its oldest form it results from ingestion of food containing botulinum toxin. To correctly evaluate the incidence of botulism it is fundamental to know the distribution of botulinum toxin-producing clostridia (Clostridium botulinum, C. baratii, C. butyricum and C. argentinense) in nature, specially in the soil, its main reservoir. In our country, this study has been carried out in a partial way. With the aim to contribute to such knowledge, 240 soil samples from Entre Ríos province were examined for C. botulinum and 35 (14.6%) samples resulted positive.

Asunto(s)

Clostridium/aislamiento & purificación , Microbiología del Suelo , Crianza de Animales Domésticos , Animales , Argentina/epidemiología , Bioensayo , Botulismo/epidemiología , Botulismo/microbiología , Botulismo/veterinaria , Bovinos , Enfermedades de los Bovinos/epidemiología , Enfermedades de los Bovinos/microbiología , Clostridium/clasificación , Clostridium/metabolismo , Clostridium botulinum/aislamiento & purificación , Clostridium botulinum/metabolismo , Reservorios de Enfermedades , Ratones , Especificidad de la Especie

RESUMEN

The lactic acid bacteria diversity of pozol, a Mexican fermented maize dough, was studied using a total DNA extraction and purification procedure and PCR amplification of 16S rDNA for gram-positive and related bacterial groups. Thirty-six clones were obtained and sequenced to 650 nucleotides. These partial sequences were identified by submission to the non-redundant nucleotide database of NCBI. The identified sequences were aligned with reference sequences of the closest related organisms. This analysis indicated that only 14 sequences were unique clones and these were identified as Lactococcus lactis, Streptococcus suis, Lactobacillus plantarum, Lact. casei, Lact. alimentarium, and Lact. delbruekii and Clostridium sp. Two non-ribosomal sequences were also detected. Unlike other environments analyzed with this molecular approach where many unidentified microorganisms are found, the identity of most sequences could be established as lactic acid bacteria, indicating that this is the main group among the gram-positive bacteria in pozol. Use of this molecular method permitted detection of lactic acid bacteria different from those previously isolated and identified by culture techniques

Asunto(s)

ADN Bacteriano/análisis , ARN Ribosómico 16S/genética , Zea mays/microbiología , Clostridium/clasificación , Clostridium/genética , Fermentación , Amplificación de Genes , Lactobacillus/clasificación , Lactobacillus/genética , Datos de Secuencia Molecular , Filogenia , Reacción en Cadena de la Polimerasa/métodos , ARN Ribosómico 16S/análisis , Streptococcaceae/clasificación , Streptococcaceae/genética

RESUMEN

Thirteen new Clostridium strains, previously isolated from soil and found to produce high amounts of solvents from glucose, hydrolyzed a great variety of alpha- and beta-glycans, including raw starch, xylan, pectin, inulin and cellulose. The sequences of the PCR-amplified DNA fragments containing the variable 3' part of one of the 16S rRNA genes were 99.5% identical. The macrorestriction pattern of two endonucleolytic digests of chromosomal DNA in the pulsed-field gel electrophoresis (PFGE) confirmed their high homogeneity on the DNA level. The complete 16S rRNA gene sequence of three selected strains was 99.8% identical to the 16S rRNA gene sequence from Clostridium butyricum and separates them from C. acetobutylicum. To the closely related four species of solventogenic clostridia a new group of strains has to be added, which has a great potential for the direct fermentation of biomass.

Asunto(s)

Clostridium/metabolismo , Polisacáridos/metabolismo , Solventes/metabolismo , Biomasa , Clostridium/clasificación , Clostridium/aislamiento & purificación , Fermentación , Hidrólisis , Microbiología Industrial , Datos de Secuencia Molecular , ARN Ribosómico 16S/genética , Homología de Secuencia de Ácido Nucleico , Microbiología del Suelo

RESUMEN

The 16S rRNA sequences and selected phenotypic characteristics were determined for six recently isolated bacteria that can tolerate high levels of hydrolyzable and condensed tannins. Bacteria were isolated from the ruminal contents of animals in different geographic locations, including Sardinian sheep (Ovis aries), Honduran and Colombian goats (Capra hircus), white-tail deer (Odocoileus virginianus) from upstate New York, and Rocky Mountain elk (Cervus elaphus nelsoni) from Oregon. Nearly complete sequences of the small-subunit rRNA genes, which were obtained by PCR amplification, cloning, and sequencing, were used for phylogenetic characterization. Comparisons of the 16S rRNA of the six isolates showed that four of the isolates were members of the genus Streptococcus and were most closely related to ruminal strains of Streptococcus bovis and the recently described organism Streptococcus gallolyticus. One of the other isolates, a gram-positive rod, clustered with the clostridia in the low-G+C-content group of gram-positive bacteria. The sixth isolate, a gram-negative rod, was a member of the family Enterobacteriaceae in the gamma subdivision of the class Proteobacteria. None of the 16S rRNA sequences of the tannin-tolerant bacteria examined was identical to the sequence of any previously described microorganism or to the sequence of any of the other organisms examined in this study. Three phylogenetically distinct groups of ruminal bacteria were isolated from four species of ruminants in Europe, North America, and South America. The presence of tannin-tolerant bacteria is not restricted by climate, geography, or host animal, although attempts to isolate tannin-tolerant bacteria from cows on low-tannin diets failed.

Asunto(s)

Clostridium/clasificación , Escherichia coli/clasificación , Taninos Hidrolizables/metabolismo , Filogenia , ARN Ribosómico 16S/genética , Rumen/microbiología , Streptococcus/clasificación , Yersinia/clasificación , Animales , Clostridium/genética , Clostridium/aislamiento & purificación , Colombia , ADN Ribosómico/genética , Ciervos , Erwinia/clasificación , Erwinia/genética , Erwinia/aislamiento & purificación , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Eubacterium/clasificación , Eubacterium/genética , Eubacterium/aislamiento & purificación , Cabras , Honduras , Taninos Hidrolizables/farmacología , New York , Oregon , Peptostreptococcus/clasificación , Peptostreptococcus/genética , Peptostreptococcus/aislamiento & purificación , Fenotipo , Ovinos , Streptococcus/genética , Streptococcus/aislamiento & purificación , Yersinia/genética , Yersinia/aislamiento & purificación