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1.
Microbiol Spectr ; 9(3): e0078421, 2021 12 22.
Artículo en Inglés | MEDLINE | ID: mdl-34756083

RESUMEN

The formation of dense, well-settling methanogenic granules is essential for the operation of high-rate, up-flow anaerobic bioreactors used for wastewater treatment. Granule formation (granulation) mechanisms have been previously proposed, but an ecological understanding of granule formation is still lacking. Additionally, much of the current research on granulation only examines the start-up phase of bioreactor operation, rather than monitoring the fate of established granules and how new granules emerge over time. This paper, therefore, attempts to provide an insight into the microbial ecology of granule formation outside the start-up phase of bioreactor operation and develop an ecological granulation model. The microbial communities of granules actively undergoing growth, breakage, and reformation were examined, and an ecological granulation model was proposed. A distinct pregranular microbial community, with a high proportion of acidogenic organisms, such as the Streptococcaceae, was identified and suggested to have a role in initiating granulation by providing simpler substrates for the methanogenic and syntrophic communities which developed during granule growth. After initial granule formation, deterministic influences on microbial community assembly increased with granule size and indicated that microbial community succession was influenced by granule growth, leading to the formation of a stepwise ecological model for granulation. IMPORTANCE Complex microbial communities in engineered environments can aggregate to form surface-attached biofilms. Others form suspended biofilms, such as methanogenic granules. The formation of dense, methanogenic granules underpins the performance of high-rate, anaerobic bioreactors in industrial wastewater treatment. Granule formation (granulation) has been well studied from a physico-chemical perspective, but the ecological basis is poorly understood. We identified a distinct, flocculent, microbial community, which was present alongside granules, comprising primary consumers likely key in providing simpler substrates to granules. This flocculent community is understudied in anaerobic digestion and may initiate, or perpetuate, granule formation. We propose that it may be possible to influence bioreactor performance (e.g., to regulate volatile fatty acid concentrations) by manipulating this community. The patterns of microbial community diversity and assembly revealed by the study indicate that cycles of granule growth and breakage lead to overall diversification of the bioreactor meta-community, with implications for bioreactor process stability.


Asunto(s)
Bacterias Anaerobias/metabolismo , Reactores Biológicos/microbiología , Metano/biosíntesis , Microbiota/fisiología , Aguas del Alcantarillado/microbiología , Adhesión Bacteriana/fisiología , Biopelículas/crecimiento & desarrollo , Floculación , Streptococcaceae/metabolismo , Purificación del Agua
2.
Biochemistry ; 60(2): 152-159, 2021 01 19.
Artículo en Inglés | MEDLINE | ID: mdl-33400518

RESUMEN

Water is key to protein structure and stability, yet the relationship between protein-water interactions and structure is poorly understood, in part because there are few techniques that permit the study of dehydrated protein structure at high resolution. Here, we describe liquid-observed vapor exchange (LOVE) NMR, a solution NMR-based method that provides residue-level information about the structure of dehydrated proteins. Using the model protein GB1, we show that LOVE NMR measurements reflect the fraction of the dried protein population trapped in a conformation where a given residue is protected from exchange with D2O vapor. Comparisons to solution hydrogen-deuterium exchange data affirm that the dried protein structure is strongly influenced by local solution stability and that the mechanism of dehydration protection exerted by the widely used protectant trehalose differs from its mechanism of stabilization in solution. Our results highlight the need for refined models of cosolute-mediated dehydration protection and demonstrate the ability of LOVE NMR to inform such models.


Asunto(s)
Aminoácidos/química , Proteínas Bacterianas/química , Deuterio/química , Hidrógeno/química , Espectroscopía de Resonancia Magnética/métodos , Streptococcaceae/metabolismo , Medición de Intercambio de Deuterio , Liofilización , Conformación Proteica
3.
PLoS One ; 8(11): e79801, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-24278181

RESUMEN

Coral disease is a global problem. Diseases are typically named or described based on macroscopic changes, but broad signs of coral distress such as tissue loss or discoloration are unlikely to be specific to a particular pathogen. For example, there appear to be multiple diseases that manifest the rapid tissue loss that characterizes 'white plague.' PhyloChip™ G3 microarrays were used to compare the bacterial community composition of both healthy and white plague-like diseased corals. Samples of lobed star coral (Orbicella annularis, formerly of the genus Montastraea[1]) were collected from two geographically distinct areas, Dry Tortugas National Park and Virgin Islands National Park, to determine if there were biogeographic differences between the diseases. In fact, all diseased samples clustered together, however there was no consistent link to Aurantimonas coralicida, which has been described as the causative agent of white plague type II. The microarrays revealed a large amount of bacterial heterogeneity within the healthy corals and less diversity in the diseased corals. Gram-positive bacterial groups (Actinobacteria, Firmicutes) comprised a greater proportion of the operational taxonomic units (OTUs) unique to healthy samples. Diseased samples were enriched in OTUs from the families Corynebacteriaceae, Lachnospiraceae, Rhodobacteraceae, and Streptococcaceae. Much previous coral disease work has used clone libraries, which seem to be methodologically biased toward recovery of Gram-negative bacterial sequences and may therefore have missed the importance of Gram-positive groups. The PhyloChip™data presented here provide a broader characterization of the bacterial community changes that occur within Orbicella annularis during the shift from a healthy to diseased state.


Asunto(s)
Antozoos/microbiología , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Actinobacteria/metabolismo , Actinomycetales/metabolismo , Animales , Rhodobacteraceae/metabolismo , Streptococcaceae/metabolismo
4.
J Bacteriol ; 194(13): 3522-33, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22522891

RESUMEN

Sulfuric volatile compounds derived from cysteine and methionine provide many dairy products with a characteristic odor and taste. To better understand and control the environmental dependencies of sulfuric volatile compound formation by the dairy starter bacteria, we have used the available genome sequence and experimental information to systematically evaluate the presence of the key enzymes and to reconstruct the general modes of transcription regulation for the corresponding genes. The genomic organization of the key genes is suggestive of a subdivision of the reaction network into five modules, where we observed distinct differences in the modular composition between the families Lactobacillaceae, Enterococcaceae, and Leuconostocaceae, on the one hand, and the family Streptococcaceae, on the other. These differences are mirrored by the way in which transcription regulation of the genes is structured in these families. In the Lactobacillaceae, Enterococcaceae, and Leuconostocaceae, the main shared mode of transcription regulation is methionine (Met) T-box-mediated regulation. In addition, the gene metK, encoding S-adenosylmethionine (SAM) synthetase, is controlled via the S(MK) box (SAM). The S(MK) box is also found upstream of metK in species of the family Streptococcaceae. However, the transcription control of the other modules is mediated via three different LysR-family regulators, MetR/MtaR (methionine), CmbR (O-acetyl[homo]serine), and HomR (O-acetylhomoserine). Redefinition of the associated DNA-binding motifs helped to identify/disentangle the related regulons, which appeared to perfectly match the proposed subdivision of the reaction network.


Asunto(s)
Cisteína/metabolismo , Industria Lechera , Regulación Bacteriana de la Expresión Génica , Lactobacillales/metabolismo , Metionina/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Biología Computacional/métodos , Regulación Enzimológica de la Expresión Génica , Lactobacillales/clasificación , Lactobacillales/enzimología , Lactobacillales/genética , Metionina Adenosiltransferasa/genética , Metionina Adenosiltransferasa/metabolismo , S-Adenosilmetionina/metabolismo , Streptococcaceae/enzimología , Streptococcaceae/genética , Streptococcaceae/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transcripción Genética
5.
Mol Microbiol ; 80(4): 1102-19, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21435032

RESUMEN

We identified a genetic context encoding a transcriptional regulator of the Rgg family and a small hydrophobic peptide (SHP) in nearly all streptococci and suggested that it may be involved in a new quorum-sensing mechanism, with SHP playing the role of a pheromone. Here, we provide further support for this hypothesis by constructing a phylogenetic tree of the Rgg and Rgg-like proteins from Gram-positive bacteria and by studying the shp/rgg1358 locus of Streptococcus thermophilus LMD-9. We identified the shp1358 gene as a target of Rgg1358, and used it to confirm the existence of the steps of a quorum-sensing mechanism including secretion, maturation and reimportation of the pheromone into the cell. We used surface plasmon resonance to demonstrate interaction between the pheromone and the regulatory protein and performed electrophoretic mobility shift assays to assess binding of the transcriptional regulator to the promoter regions of its target genes. The active form of the pheromone was identified by mass spectrometry. Our findings demonstrate that the shp/rgg1358 locus encodes two components of a novel quorum-sensing mechanism involving a transcriptional regulator of the Rgg family and a SHP pheromone that is detected and reimported into the cell by the Ami oligopeptide transporter.


Asunto(s)
Proteínas Bacterianas/metabolismo , Feromonas/metabolismo , Percepción de Quorum , Streptococcaceae/metabolismo , Transactivadores/metabolismo , Secuencia de Aminoácidos , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Proteínas de Unión al ADN , Ensayo de Cambio de Movilidad Electroforética , Regulación Bacteriana de la Expresión Génica , Interacciones Hidrofóbicas e Hidrofílicas , Espectrometría de Masas , Filogenia , Regiones Promotoras Genéticas , Análisis de Secuencia de ADN , Transducción de Señal , Streptococcaceae/química , Streptococcaceae/genética , Resonancia por Plasmón de Superficie , Transactivadores/química , Transactivadores/genética , Transcripción Genética
6.
Syst Appl Microbiol ; 32(6): 438-48, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19243908

RESUMEN

Thirty samples of Italian durum wheat semolina and whole durum wheat semolina, generally used for the production of Southern Italy's traditional breads, were subjected to microbiological analysis in order to explore their lactic acid bacteria (LAB) diversity and to find strains with antifungal activity. A total of 125 presumptive LAB isolates (Gram-positive and catalase-negative) were characterized by repetitive extragenic palindromic-PCR (REP-PCR) and sequence analysis of the 16S rRNA gene, leading to the identification of the following species: Weissella confusa, Weissella cibaria, Leuconostoc citreum, Leuconostoc mesenteroides, Lactococcus lactis, Lactobacillus rossiae and Lactobacillus plantarum. The REP-PCR results delineated 17 different patterns whose cluster analysis clearly differentiated W. cibaria from W. confusa isolates. Seventeen strains, each characterized by a different REP-PCR pattern, were screened for their antifungal properties. They were grown in a flour-based medium, comparable to a real food system, and the resulting fermentation products (FPs) were tested against fungal species generally contaminating bakery products, Aspergillus niger, Penicillium roqueforti and Endomyces fibuliger. The results of the study indicated a strong inhibitory activity - comparable to that obtained with the common preservative calcium propionate (0.3% w/v) - of ten LAB strains against the most widespread contaminant of bakery products, P. roqueforti. The screening also highlighted the unexplored antifungal activity of L. citreum, L. rossiae and W. cibaria (1 strain), which inhibited all fungal strains to the same or a higher extent compared with calcium propionate. The fermentation products of these three strains were characterized by low pH values, and a high content of lactic and acetic acids.


Asunto(s)
Antibiosis , Pan/microbiología , Ecosistema , Contaminación de Alimentos/prevención & control , Hongos/crecimiento & desarrollo , Lactobacillaceae , Streptococcaceae , Triticum/microbiología , Ácido Acético/metabolismo , Ácido Acético/farmacología , Aspergillus niger/efectos de los fármacos , Aspergillus niger/crecimiento & desarrollo , Endomyces/efectos de los fármacos , Endomyces/crecimiento & desarrollo , Hongos/clasificación , Hongos/efectos de los fármacos , Italia , Ácido Láctico/metabolismo , Ácido Láctico/farmacología , Lactobacillaceae/genética , Lactobacillaceae/crecimiento & desarrollo , Lactobacillaceae/aislamiento & purificación , Lactobacillaceae/metabolismo , Lactobacillus/genética , Lactobacillus/crecimiento & desarrollo , Lactobacillus/aislamiento & purificación , Lactobacillus/metabolismo , Lactobacillus plantarum/genética , Lactobacillus plantarum/crecimiento & desarrollo , Lactobacillus plantarum/aislamiento & purificación , Lactobacillus plantarum/metabolismo , Leuconostoc/genética , Leuconostoc/crecimiento & desarrollo , Leuconostoc/aislamiento & purificación , Leuconostoc/metabolismo , Pruebas de Sensibilidad Microbiana , Datos de Secuencia Molecular , Penicillium/efectos de los fármacos , Penicillium/crecimiento & desarrollo , Reacción en Cadena de la Polimerasa/métodos , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Streptococcaceae/genética , Streptococcaceae/crecimiento & desarrollo , Streptococcaceae/aislamiento & purificación , Streptococcaceae/metabolismo , Triticum/efectos de los fármacos
7.
RNA ; 14(4): 685-95, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-18305186

RESUMEN

Bioinformatics searches of eubacterial genomes have yielded many riboswitch candidates where the identity of the ligand is not immediately obvious on examination of associated genes. One of these motifs is found exclusively in the family Streptococcaceae within the 5' untranslated regions (UTRs) of genes encoding the hypothetical membrane protein classified as COG4708 or DUF988. While the function of this protein class is unproven, a riboswitch binding the queuosine biosynthetic intermediate pre-queuosine(1) (preQ(1)) has been identified in the 5' UTR of homologous genes in many Firmicute species of bacteria outside of Streptococcaceae. Here we show that a representative of the COG4708 RNA motif from Streptococcus pneumoniae R6 also binds preQ(1). Furthermore, representatives of this RNA have structural and molecular recognition characteristics that are distinct from those of the previously described preQ(1) riboswitch class. PreQ(1) is the second metabolite for which two or more distinct classes of natural aptamers exist, indicating that natural aptamers utilizing different structures to bind the same metabolite may be more common than is currently known. Additionally, the association of preQ(1) binding RNAs with most genes encoding proteins classified as COG4708 strongly suggests that these proteins function as transporters for preQ(1) or another queuosine biosynthetic intermediate.


Asunto(s)
Aptámeros de Nucleótidos/clasificación , Aptámeros de Nucleótidos/metabolismo , Pirimidinonas/metabolismo , Pirroles/metabolismo , ARN Bacteriano/metabolismo , Streptococcaceae/metabolismo , Regiones no Traducidas 5' , Aptámeros de Nucleótidos/genética , Secuencia de Bases , Sitios de Unión/genética , Biología Computacional , Genes Bacterianos , Cinética , Ligandos , Modelos Moleculares , Datos de Secuencia Molecular , Mutación , Conformación de Ácido Nucleico , Filogenia , ARN Bacteriano/genética , Homología de Secuencia de Ácido Nucleico , Streptococcaceae/genética , Streptococcus pneumoniae/genética , Streptococcus pneumoniae/metabolismo
8.
J Mol Microbiol Biotechnol ; 14(1-3): 67-73, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-17957112

RESUMEN

Gene expression regulation often involves the recognition of particular DNA or RNA sequences, called motifs. Detection and characterization of such motifs together with biological expertise allow to build gene expression regulatory maps that facilitate the comprehension of complex cellular processes. In this frame, we developed a software integrating relevant information for the detection and characterization of conserved motifs in genomic sequences. A relational database was built up to host data related to genomic information and transcriptional experiments. A user-friendly interface was designed to allow a convenient representation of these data and to run the detection motif program. A set of complementary utilities was also developed to improve the determination of motif consensus sequences and the detection of additional potential regulator targets in the genome.


Asunto(s)
Secuencias de Aminoácidos , Biología Computacional/métodos , Regulación Bacteriana de la Expresión Génica , Programas Informáticos , Streptococcaceae/genética , Secuencia de Bases , Bases de Datos de Ácidos Nucleicos , Perfilación de la Expresión Génica , Genómica , Lactococcus/química , Lactococcus/genética , Lactococcus/metabolismo , Datos de Secuencia Molecular , Filogenia , Streptococcaceae/química , Streptococcaceae/metabolismo , Streptococcus/química , Streptococcus/genética , Streptococcus/metabolismo , Interfaz Usuario-Computador
9.
Lett Appl Microbiol ; 45(2): 190-3, 2007 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-17651217

RESUMEN

AIMS: To investigate the effects of two prebiotics and trehalose on the production of bacteriocins. METHODS AND RESULTS: Four carbohydrates [dextrose, fructo-oligosaccharides (FOS), raffinose, and trehalose] were used as the sole carbon source in a simple broth. Five bacteriocin-producing strains of bacteria, including those producing nisin, enteriocin, and other bacteriocins, were used, and their inhibitory activities when grown on each carbohydrate were determined. The inhibitory activity assay was performed using the agar well diffusion method, and Lactobacillus sakei JCM 1,157(T) was used as the indicator strain. Effective enhancement of bacteriocin production was observed with FOS and trehalose incubation. CONCLUSIONS: The results suggest that FOS and trehalose can effectively enhance the production of the five kinds of bacteriocins evaluated in this study. SIGNIFICANCE AND IMPACT OF THE STUDY: This study offers useful information for not only a new application of FOS and trehalose, but also the potential improvement of food preservation.


Asunto(s)
Bacteriocinas/biosíntesis , Lactobacillus , Oligosacáridos/farmacología , Streptococcaceae , Trehalosa/farmacología , Bacteriocinas/farmacología , Biotecnología/métodos , Conservación de Alimentos/métodos , Lactobacillus/efectos de los fármacos , Lactobacillus/crecimiento & desarrollo , Lactobacillus/metabolismo , Pruebas de Sensibilidad Microbiana , Oligosacáridos/metabolismo , Streptococcaceae/efectos de los fármacos , Streptococcaceae/crecimiento & desarrollo , Streptococcaceae/metabolismo , Trehalosa/metabolismo
10.
Appl Environ Microbiol ; 73(6): 1809-24, 2007 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17277227

RESUMEN

The Ghanaian cocoa bean heap fermentation process was studied through a multiphasic approach, encompassing both microbiological and metabolite target analyses. A culture-dependent (plating and incubation, followed by repetitive-sequence-based PCR analyses of picked-up colonies) and culture-independent (denaturing gradient gel electrophoresis [DGGE] of 16S rRNA gene amplicons, PCR-DGGE) approach revealed a limited biodiversity and targeted population dynamics of both lactic acid bacteria (LAB) and acetic acid bacteria (AAB) during fermentation. Four main clusters were identified among the LAB isolated: Lactobacillus plantarum, Lactobacillus fermentum, Leuconostoc pseudomesenteroides, and Enterococcus casseliflavus. Other taxa encompassed, for instance, Weissella. Only four clusters were found among the AAB identified: Acetobacter pasteurianus, Acetobacter syzygii-like bacteria, and two small clusters of Acetobacter tropicalis-like bacteria. Particular strains of L. plantarum, L. fermentum, and A. pasteurianus, originating from the environment, were well adapted to the environmental conditions prevailing during Ghanaian cocoa bean heap fermentation and apparently played a significant role in the cocoa bean fermentation process. Yeasts produced ethanol from sugars, and LAB produced lactic acid, acetic acid, ethanol, and mannitol from sugars and/or citrate. Whereas L. plantarum strains were abundant in the beginning of the fermentation, L. fermentum strains converted fructose into mannitol upon prolonged fermentation. A. pasteurianus grew on ethanol, mannitol, and lactate and converted ethanol into acetic acid. A newly proposed Weissella sp., referred to as "Weissella ghanaensis," was detected through PCR-DGGE analysis in some of the fermentations and was only occasionally picked up through culture-based isolation. Two new species of Acetobacter were found as well, namely, the species tentatively named "Acetobacter senegalensis" (A. tropicalis-like) and "Acetobacter ghanaensis" (A. syzygii-like).


Asunto(s)
Acetobacter/aislamiento & purificación , Biodiversidad , Reactores Biológicos , Cacao/metabolismo , Bacterias Grampositivas/aislamiento & purificación , Lactobacillus/aislamiento & purificación , Streptococcaceae/aislamiento & purificación , Ácido Acético/metabolismo , Acetobacter/clasificación , Acetobacter/metabolismo , Cacao/microbiología , Metabolismo de los Hidratos de Carbono , Ácido Cítrico/metabolismo , Análisis por Conglomerados , Recuento de Colonia Microbiana , Dermatoglifia del ADN , ADN Bacteriano/genética , ADN Ribosómico/genética , Etanol/metabolismo , Fermentación , Fructosa/metabolismo , Bacterias Grampositivas/clasificación , Bacterias Grampositivas/metabolismo , Ácido Láctico/metabolismo , Lactobacillus/clasificación , Lactobacillus/metabolismo , Manitol/metabolismo , Streptococcaceae/clasificación , Streptococcaceae/metabolismo , Levaduras/metabolismo
12.
Antivir Chem Chemother ; 17(4): 167-74, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-17066895

RESUMEN

Here we report that sparsomycin, a streptococcal metabolite, enhances the replication of HIV-1 in multiple human T cell lines at a concentration of 400 nM. In addition to wild-type HIV-1, sparsomycin also accelerated the replication of low-fitness, drug-resistant mutants carrying either D30N or L90M within HIV-1 protease, which are frequently found mutations in HIV-1-infected patients on highly active antiretroviral therapy (HAART). Of particular interest was that replication enhancement appeared profound when HIV-1 such as the L90M-carrying mutant displayed relatively slower replication kinetics. The presence of sparsomycin did not immediately select the fast-replicating HIV-1 mutants in culture. In addition, sparsomycin did not alter the 50% inhibitory concentration (IC50) of antiretroviral drugs directed against HIV-1 including nucleoside reverse transcriptase inhibitors (lamivudine and stavudine), non-nucleoside reverse transcriptase inhibitor (nevirapine) and protease inhibitors (nelfinavir, amprenavir and indinavir). The IC50s of both zidovudine and lopinavir against multidrug resistant HIV-1 in the presence of sparsomycin were similar to those in the absence of sparsomycin. The frameshift reporter assay and Western blot analysis revealed that the replication-boosting effect was partly due to the sparsomycin's ability to increase the -1 frameshift efficiency required to produce the Gag-Pol transcript. In conclusion, the use of sparsomycin should be able to facilitate the drug resistance profiling of the clinical isolates and the study on the low-fitness viruses.


Asunto(s)
Farmacorresistencia Viral/efectos de los fármacos , VIH-1/efectos de los fármacos , Esparsomicina/farmacología , Replicación Viral/efectos de los fármacos , Células Cultivadas , Relación Dosis-Respuesta a Droga , VIH-1/genética , Humanos , Concentración 50 Inhibidora , Modelos Biológicos , Mutación , Streptococcaceae/metabolismo , Transfección
13.
Appl Environ Microbiol ; 71(7): 3399-404, 2005 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16000741

RESUMEN

The effect of high-pressure (HP) treatments combined with bacteriocins of lactic acid bacteria (LAB) produced in situ on the survival of Escherichia coli O157:H7 in cheese was investigated. Cheeses were manufactured from raw milk inoculated with E. coli O157:H7 at approximately 10(5) CFU/ml. Seven different bacteriocin-producing LAB were added at approximately 10(6) CFU/ml as adjuncts to the starter. Cheeses were pressurized on day 2 or 50 at 300 MPa for 10 min or 500 MPa for 5 min, at 10 degrees C in both cases. After 60 days, E. coli O157:H7 counts in cheeses manufactured without bacteriocin-producing LAB and not pressurized were 5.1 log CFU/g. A higher inactivation of E. coli O157:H7 was achieved in cheeses without bacteriocin-producing LAB when 300 MPa was applied on day 50 (3.8-log-unit reduction) than if applied on day 2 (1.3-log-unit reduction). Application of 500 MPa eliminated E. coli O157:H7 in 60-day-old cheeses. Cheeses made with bacteriocin-producing LAB and not pressurized showed a slight reduction of the pathogen. Pressurization at 300 MPa on day 2 and addition of lacticin 481-, nisin A-, bacteriocin TAB 57-, or enterocin AS-48-producing LAB were synergistic and reduced E. coli O157:H7 counts to levels below 2 log units in 60-day-old cheeses. Pressurization at 300 MPa on day 50 and addition of nisin A-, bacteriocin TAB 57-, enterocin I-, or enterocin AS-48-producing LAB completely inactivated E. coli O157:H7 in 60-day-old cheeses. The application of reduced pressures combined with bacteriocin-producing LAB is a feasible procedure to improve cheese safety.


Asunto(s)
Bacteriocinas/metabolismo , Queso/microbiología , Escherichia coli O157/crecimiento & desarrollo , Leche/microbiología , Streptococcaceae/crecimiento & desarrollo , Animales , Bacteriocinas/farmacología , Recuento de Colonia Microbiana , Enterococcus faecalis/crecimiento & desarrollo , Enterococcus faecalis/metabolismo , Enterococcus faecium/crecimiento & desarrollo , Enterococcus faecium/metabolismo , Escherichia coli O157/efectos de los fármacos , Conservación de Alimentos/métodos , Presión Hidrostática , Lactococcus lactis/crecimiento & desarrollo , Lactococcus lactis/metabolismo , Streptococcaceae/metabolismo
14.
Nucleic Acids Res ; 32(11): 3340-53, 2004.
Artículo en Inglés | MEDLINE | ID: mdl-15215334

RESUMEN

Regulation of the methionine biosynthesis and transport genes in bacteria is rather diverse and involves two RNA-level regulatory systems and at least three DNA-level systems. In particular, the methionine metabolism in Gram-positive bacteria was known to be controlled by the S-box and T-box mechanisms, both acting on the level of premature termination of transcription. Using comparative analysis of genes, operons and regulatory elements, we described the methionine metabolic pathway and the methionine regulons in available genomes of Gram-positive bacteria. A large number of methionine-specific RNA elements were identified. S-boxes were shown to be widely distributed in Bacillales and Clostridia, whereas methionine-specific T-boxes occurred mostly in Lactobacillales. A candidate binding signal (MET-box) for a hypothetical methionine regulator, possibly MtaR, was identified in Streptococcaceae, the only family in the Bacillus/Clostridium group of Gram-positive bacteria having neither S-boxes, nor methionine-specific T-boxes. Positional analysis of methionine-specific regulatory sites complemented by genome context analysis lead to identification of new members of the methionine regulon, both enzymes and transporters, and reconstruction of the methionine metabolism in various bacterial genomes. In particular, we found candidate transporters for methionine (MetT) and methylthioribose (MtnABC), as well as new enzymes forming the S-adenosylmethionine recycling pathway. Methionine biosynthetic enzymes in various bacterial species are quite variable. In particular, Oceanobacillus iheyensis possibly uses a homolog of the betaine-homocysteine methyltransferase bhmT gene from vertebrates to substitute missing bacterial-type methionine synthases.


Asunto(s)
Regulación Bacteriana de la Expresión Génica , Bacterias Grampositivas/genética , Bacterias Grampositivas/metabolismo , Metionina/metabolismo , Secuencia de Bases , Transporte Biológico , Genoma Bacteriano , Genómica , Datos de Secuencia Molecular , Filogenia , ARN Bacteriano/química , Secuencias Reguladoras de Ácido Ribonucleico , Regulón , S-Adenosilmetionina/metabolismo , Intercambiadores de Sodio-Hidrógeno/clasificación , Streptococcaceae/genética , Streptococcaceae/metabolismo
15.
J Immunol ; 172(2): 1198-202, 2004 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-14707097

RESUMEN

The lectin pathway of complement is activated when a carbohydrate recognition complex and associated serine proteases binds to the surface of a pathogen. Three recognition subcomponents have been shown to form active initiation complexes: mannan-binding lectin (MBL), L-ficolin, and H-ficolin. The importance of MBL in antimicrobial host defense is well recognized, but the role of the ficolins remains largely undefined. This report shows that L-ficolin specifically binds to lipoteichoic acid (LTA), a cell wall component found in all Gram-positive bacteria. Immobilized LTA from Staphylococcus aureus binds L-ficolin complexes from sera, and these complexes initiate lectin pathway-dependent C4 turnover. C4 activation correlates with serum L-ficolin concentration, but not with serum MBL levels. L-ficolin binding and corresponding levels of C4 turnover were observed on LTA purified from other clinically important bacteria, including Streptococcus pyogenes and Streptococcus agalactiae. None of the LTA preparations bound MBL, H-ficolin, or the classical pathway recognition molecule, C1q.


Asunto(s)
Proteínas Portadoras/metabolismo , Activación de Complemento/inmunología , Bacterias Grampositivas/inmunología , Bacterias Grampositivas/metabolismo , Lectinas/metabolismo , Lipopolisacáridos/metabolismo , Ácidos Teicoicos/metabolismo , Adyuvantes Inmunológicos/metabolismo , Proteínas Portadoras/sangre , Pared Celular/inmunología , Pared Celular/metabolismo , Complemento C4/metabolismo , Humanos , Hidrólisis , Inmunidad Innata , Lectina de Unión a Manosa/metabolismo , Serina Proteasas Asociadas a la Proteína de Unión a la Manosa , Serina Endopeptidasas/metabolismo , Staphylococcus aureus/inmunología , Staphylococcus aureus/metabolismo , Streptococcaceae/inmunología , Streptococcaceae/metabolismo , Ficolinas
16.
Clin Microbiol Infect ; 9(9): 976-9, 2003 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-14616691

RESUMEN

To evaluate procedures for the identification of Aerococcus urinae, we examined 24 alpha-hemolytic non-enterococcal bacterial isolates from 4373 urine samples. Published procedures were compared with 16s rRNA sequencing and biochemical profiling (BBL-Crystal-GP). 16s rRNA sequencing and BBL-Crystal-GP identified the same 13 isolates as A. urinae. Published tests failed to distinguish the 13 A. urinae isolates from eight non-A. urinae isolates; several tests exhibited no discrimination. Ciprofloxacin and trimethoprim susceptibility and growth at 45 degrees C improved discrimination. For urinary isolates, standard procedures for identification of A. urinae are redundant and insufficiently discriminatory, and may need revision. BBL-Crystal-GP is an accurate alternative.


Asunto(s)
Infecciones por Bacterias Grampositivas/orina , Streptococcaceae/aislamiento & purificación , Adulto , Anciano , Anciano de 80 o más Años , Niño , ADN Bacteriano/química , ADN Bacteriano/genética , Femenino , Infecciones por Bacterias Grampositivas/microbiología , Humanos , Masculino , Persona de Mediana Edad , Noruega , ARN Ribosómico 16S/química , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Streptococcaceae/genética , Streptococcaceae/metabolismo
17.
Appl Environ Microbiol ; 69(1): 444-51, 2003 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-12514026

RESUMEN

A total of 161 low-G+C-content gram-positive bacteria isolated from whole-crop paddy rice silage were classified and subjected to phenotypic and genetic analyses. Based on morphological and biochemical characters, these presumptive lactic acid bacterium (LAB) isolates were divided into 10 groups that included members of the genera Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, and WEISSELLA: Analysis of the 16S ribosomal DNA (rDNA) was used to confirm the presence of the predominant groups indicated by phenotypic analysis and to determine the phylogenetic affiliation of representative strains. The virtually complete 16S rRNA gene was PCR amplified and sequenced. The sequences from the various LAB isolates showed high degrees of similarity to those of the GenBank reference strains (between 98.7 and 99.8%). Phylogenetic trees based on the 16S rDNA sequence displayed high consistency, with nodes supported by high bootstrap values. With the exception of one species, the genetic data was in agreement with the phenotypic identification. The prevalent LAB, predominantly homofermentative (66%), consisted of Lactobacillus plantarum (24%), Lactococcus lactis (22%), Leuconostoc pseudomesenteroides (20%), Pediococcus acidilactici (11%), Lactobacillus brevis (11%), Enterococcus faecalis (7%), Weissella kimchii (3%), and Pediococcus pentosaceus (2%). The present study, the first to fully document rice-associated LAB, showed a very diverse community of LAB with a relatively high number of species involved in the fermentation process of paddy rice silage. The comprehensive 16S rDNA-based approach to describing LAB community structure was valuable in revealing the large diversity of bacteria inhabiting paddy rice silage and enabling the future design of appropriate inoculants aimed at improving its fermentation quality.


Asunto(s)
Variación Genética , Lactobacillus/genética , Oryza/microbiología , Filogenia , Ensilaje/microbiología , Streptococcaceae/genética , ADN Ribosómico/análisis , Fermentación , Lactobacillus/clasificación , Lactobacillus/aislamiento & purificación , Lactobacillus/metabolismo , Datos de Secuencia Molecular , Fenotipo , Reacción en Cadena de la Polimerasa , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Streptococcaceae/clasificación , Streptococcaceae/aislamiento & purificación , Streptococcaceae/metabolismo
18.
J Appl Microbiol ; 92(5): 1005-13, 2002.
Artículo en Inglés | MEDLINE | ID: mdl-11972707

RESUMEN

AIMS: In this study we determined the extent to which lactic acid bacteria (LAB) occurred in brandy base wines, their ability to catalyse the malolactic fermentation (MLF) and the effect of MLF on the quality of the base wine and the brandy distillate. METHODS AND RESULTS: Lactic acid bacteria were isolated and enumerated from grape juice, experimental and commercially produced brandy base wines. Spontaneous MLF occurred in approximately 50% of the commercial base wines. The occurrence of MLF had an influence on the quality of the base wines and the resulting distillates. In samples where MLF occurred there was a loss of fruitiness and in the intensity of aroma. Volatile compounds like iso-amyl acetate, ethyl acetate, ethyl caproate, 2-phenethyl acetate and hexyl acetate decreased in samples having undergone MLF, while ethyl lactate, acetic acid and diethyl succinate increased in the same samples. CONCLUSIONS: Spontaneous malolactic fermentation does occur in commercial brandy base wines and it has an influence on base wine and brandy quality. SIGNIFICANCE AND IMPACT OF THE STUDY: This study showed that MLF influences the quality of the base wine and the resulting distillate and with this in mind commercial base wine producers should be able to produce brandy of higher quality.


Asunto(s)
Lactatos/metabolismo , Malatos/metabolismo , Vino/microbiología , Fermentación , Lactobacillus/aislamiento & purificación , Lactobacillus/metabolismo , Odorantes , Streptococcaceae/aislamiento & purificación , Streptococcaceae/metabolismo , Vitis/microbiología , Vino/normas
19.
J Immunol ; 168(7): 3502-6, 2002 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-11907111

RESUMEN

Ficolins are a group of proteins which consist of a collagen-like domain and a fibrinogen-like domain. In human serum, there are two types of ficolins named L-ficolin/P35 and H-ficolin (Hakata Ag), both of which have lectin activity. We recently demonstrated that L-ficolin/P35 is associated with mannose-binding lectin (MBL)-associated serine proteases (MASP) 1 and 2 and small MBL-associated protein (sMAP), and that the complex activates the lectin pathway. In this study, we report the characterization of H-ficolin in terms of its ability to activate complement. Western blotting analysis showed the presence of MASP-1, MASP-2, MASP-3, and sMAP in H-ficolin preparations isolated from Cohn Fraction III. The MASPs in the preparations had proteolytic activities against C4, C2, and C3 in the fluid phase. When H-ficolin preparations were bound to anti-H-ficolin Ab which had been coated on ELISA plates, they activated C4, although no C4 activation was noted when anti-MBL and anti-L-ficolin/P35 were used. H-ficolin binds to PSA, a polysaccharide produced by Aerococcus viridans. C4 was activated by H-ficolin preparations bound to PSA which had been coated on ELISA plates. These results indicate that H-ficolin is a second ficolin which is associated with MASPs and sMAP, and which activates the lectin pathway.


Asunto(s)
Activación de Complemento/inmunología , Glicoproteínas/fisiología , Lectinas/metabolismo , Anticuerpos Monoclonales/metabolismo , Adhesión Bacteriana/inmunología , Sitios de Unión de Anticuerpos , Proteínas Portadoras/metabolismo , Colectinas , Enzimas Activadoras de Complemento/aislamiento & purificación , Enzimas Activadoras de Complemento/metabolismo , Enzimas Activadoras de Complemento/fisiología , Glicoproteínas/inmunología , Glicoproteínas/metabolismo , Humanos , Serina Proteasas Asociadas a la Proteína de Unión a la Manosa , Polisacáridos Bacterianos/metabolismo , Unión Proteica/inmunología , Serina Endopeptidasas/inmunología , Serina Endopeptidasas/aislamiento & purificación , Serina Endopeptidasas/metabolismo , Serina Endopeptidasas/fisiología , Streptococcaceae/metabolismo
20.
Appl Microbiol Biotechnol ; 58(1): 73-6, 2002 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11831477

RESUMEN

Dihydroxyacetone phosphate is essential for the synthesis of polyhydroxylated compounds used as components or precursors of active pharmaceutical substances, such as antibiotics or glycosidase inhibitors. Dihydroxyacetone phosphate was produced by enzymatic oxidation of L-alpha-glycerophosphate in the presence of glycerophosphate oxidase or Aerococcus viridans coimmobilized with a hydrogen peroxide-decomposing enzyme. The microencapsulation of A. viridans with catalase in sodium alginate showed a conversion of 98.5%; the conversion percentage remained constant in all five runs. Liquid chromatography of the product revealed that the product peak corresponded to that of the dihydroxyacetone phosphate internal standard. This indicated a high degree of product purity.


Asunto(s)
Biotecnología/métodos , Catalasa/metabolismo , Dihidroxiacetona Fosfato/metabolismo , Enzimas Inmovilizadas , Streptococcaceae/metabolismo , Alginatos , Catalasa/química , Células Inmovilizadas , Ácido Glucurónico , Glicerolfosfato Deshidrogenasa/metabolismo , Glicerofosfatos/metabolismo , Ácidos Hexurónicos , Oxidación-Reducción , Streptococcaceae/química
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