RESUMO
An aerobic endospore-forming bacillus (NVH 391-98(T)) was isolated during a severe food poisoning outbreak in France in 1998, and four other similar strains have since been isolated, also mostly from food poisoning cases. Based on 16S rRNA gene sequence similarity, these strains were shown to belong to the Bacillus cereus Group (over 97% similarity with the current Group species) and phylogenetic distance from other validly described species of the genus Bacillus was less than 95%. Based on 16S rRNA gene sequence similarity and MLST data, these novel strains were shown to form a robust and well-separated cluster in the B. cereus Group, and constituted the most distant cluster from species of this Group. Major fatty acids (iso-C(15:0), C(16:0), iso-C(17:0), anteiso-C(15 : 0), iso-C(16:0), iso-C(13:0)) supported the affiliation of these strains to the genus Bacillus, and more specifically to the B. cereus Group. NVH 391-98(T) taxon was more specifically characterized by an abundance of iso-C(15:0) and low amounts of iso-C(13:0) compared with other members of the B. cereus Group. Genome similarity together with DNA-DNA hybridization values and physiological and biochemical tests made it possible to genotypically and phenotypically differentiate NVH 391-98(T) taxon from the six current B. cereus Group species. NVH 391-98(T) therefore represents a novel species, for which the name Bacillus cytotoxicus sp. nov. is proposed, with the type strain NVH 391-98(T) (= DSM 22905(T) = CIP 110041(T)).
Assuntos
Bacillus/classificação , Doenças Transmitidas por Alimentos , Filogenia , Bacillus/genética , Bacillus/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/análise , França , Tipagem de Sequências Multilocus , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
The Bacillus cereus group comprises genetically related Gram-positive spore-forming bacteria that colonize a wide range of ecological niches and hosts. Despite their high degree of genome conservation, extrachromosomal genetic material diverges between these species. The discriminating properties of the B. cereus group strains are mainly due to plasmid-borne toxins, reflecting the importance of horizontal gene transfers in bacterial evolution and species definition. To investigate how a newly acquired megaplasmid can impact the transcriptome of its host, we transferred the pCER270 from the emetic B. cereus strains to phylogenetically distant B. cereus group strains. RNA-sequencing experiments allowed us to determine the transcriptional influence of the plasmid on host gene expression and the impact of the host genomic background on the pCER270 gene expression. Our results show a transcriptional cross-regulation between the megaplasmid and the host genome. pCER270 impacted carbohydrate metabolism and sporulation genes expression, with a higher effect in the natural host of the plasmid, suggesting a role of the plasmid in the adaptation of the carrying strain to its environment. In addition, the host genomes also modulated the expression of pCER270 genes. Altogether, these results provide an example of the involvement of megaplasmids in the emergence of new pathogenic strains.
Assuntos
Bacillus , Bacillus cereus/genética , Plasmídeos/genética , Sequência de Bases , CromossomosRESUMO
We report the complete genome sequence of Lactococcus lactis subsp. cremoris A76, a dairy strain isolated from a cheese production outfit. Genome analysis detected two contiguous islands fitting to the L. lactis subsp. lactis rather than to the L. lactis subsp. cremoris lineage. This indicates the existence of genetic exchange between the diverse subspecies, presumably related to the technological process.
Assuntos
DNA Bacteriano/química , DNA Bacteriano/genética , Laticínios/microbiologia , Genoma Bacteriano , Lactococcus lactis/genética , Lactococcus lactis/isolamento & purificação , Evolução Molecular , Ilhas Genômicas , Dados de Sequência Molecular , Recombinação Genética , Análise de Sequência de DNARESUMO
Highly hemolytic strain Bacillus cereus F837/76 was isolated in 1976 from a contaminated prostate wound. The complete nucleotide sequence of this strain reported here counts nearly 36,500 single-nucleotide differences from the closest sequenced strain, Bacillus thuringiensis Al Hakam. F827/76 also contains a 10-kb plasmid that was not detected in the Al Hakam strain.
Assuntos
Bacillus cereus/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Genoma Bacteriano , Bacillus cereus/isolamento & purificação , Bacillus cereus/patogenicidade , Infecções por Bactérias Gram-Positivas/microbiologia , Hemólise , Humanos , Masculino , Dados de Sequência Molecular , Plasmídeos , Próstata/microbiologia , Análise de Sequência de DNA , Infecção dos Ferimentos/microbiologiaRESUMO
Cell wall peptidoglycan assembly is a tightly regulated process requiring the combined action of multienzyme complexes. In this study we provide direct evidence showing that substrate transformations occurring at the different stages of this process play a crucial role in the spatial and temporal coordination of the cell wall synthesis machinery. Peptidoglycan substrate alteration was investigated in the Gram-positive bacterium Lactococcus lactis by substituting the peptidoglycan precursor biosynthesis genes of this bacterium for those of the vancomycin-resistant bacterium Lactobacillus plantarum. A set of L. lactis mutant strains in which the normal d-Ala-ended precursors were partially or totally replaced by d-Lac-ended precursors was generated. Incorporation of the altered precursor into the cell wall induced morphological changes arising from a defect in cell elongation and cell separation. Structural analysis of the muropeptides confirmed that the activity of multiple enzymes involved in peptidoglycan synthesis was altered. Optimization of this altered pathway was necessary to increase the level of vancomycin resistance conferred by the utilization of d-Lac-ended peptidoglycan precursors in the mutant strains. The implications of these findings on the control of bacterial cell morphogenesis and the mechanisms of vancomycin resistance are discussed.
Assuntos
Parede Celular/metabolismo , Lactococcus lactis/metabolismo , Peptidoglicano/química , Antibacterianos/farmacologia , Proliferação de Células , Resistência Microbiana a Medicamentos , Genoma , Ácido Láctico/química , Meticilina/química , Modelos Biológicos , Mutação , Proteínas de Ligação às Penicilinas/metabolismo , Plasmídeos/metabolismo , Análise de Sequência de DNA , Vancomicina/farmacologiaRESUMO
BACKGROUND: Since the prolonged use of insecticidal proteins has led to toxin resistance, it is important to search for novel insecticidal protein genes (IPGs) that are effective in controlling resistant insect populations. IPGs are usually encoded in the genomes of entomopathogenic bacteria, especially in large plasmids in strains of the ubiquitous soil bacteria, Bacillus thuringiensis (Bt). Since there are often multiple similar IPGs encoded by such plasmids, their assemblies are typically fragmented and many IPGs are scattered through multiple contigs. As a result, existing gene prediction tools (that analyze individual contigs) typically predict partial rather than complete IPGs, making it difficult to conduct downstream IPG engineering efforts in agricultural genomics. METHODS: Although it is difficult to assemble IPGs in a single contig, the structure of the genome assembly graph often provides clues on how to combine multiple contigs into segments encoding a single IPG. RESULTS: We describe ORFograph, a pipeline for predicting IPGs in assembly graphs, benchmark it on (meta)genomic datasets, and discover nearly a hundred novel IPGs. This work shows that graph-aware gene prediction tools enable the discovery of greater diversity of IPGs from (meta)genomes. CONCLUSIONS: We demonstrated that analysis of the assembly graphs reveals novel candidate IPGs. ORFograph identified both already known genes "hidden" in assembly graphs and potential novel IPGs that evaded existing tools for IPG identification. As ORFograph is fast, one could imagine a pipeline that processes many (meta)genomic assembly graphs to identify even more novel IPGs for phenotypic testing than would previously be inaccessible by traditional gene-finding methods. While here we demonstrated the results of ORFograph only for IPGs, the proposed approach can be generalized to any class of genes. Video abstract.
Assuntos
Inseticidas , Algoritmos , Genômica , Metagenoma , MetagenômicaRESUMO
Bacillus thuringiensis serovar israelensis is the most widely used natural biopesticide against mosquito larvae worldwide. Its lineage has been actively studied and a plasmid-free strain, B. thuringiensis serovar israelensis BGSC 4Q7 (4Q7), has been produced. Previous sequencing of the genome of this strain has revealed the persistent presence of a 235 kb extrachromosomal element, pBtic235, which has been shown to be an inducible prophage, although three putative chromosomal prophages have been lost. Moreover, a 492 kb region, potentially including the standard replication terminus, has also been deleted in the 4Q7 strain, indicating an absence of essential genes in this area. We reanalysed the genome coverage distribution of reads for the previously sequenced variant strain, and sequenced two independently maintained samples of the 4Q7 strain. A 553 kb area, close to the 492 kb deletion, was found to be duplicated. This duplication presumably restored the equal sizes of the replichores, and a balanced functioning of replication termination. An analysis of genome assembly graphs revealed a transient association of the host chromosome with the pBtic235 element. This association may play a functional role in the replication of the bacterial chromosome, and the termination of this process in particular. The genome-restructuring events detected may modify the genetic status of cytotoxic or haemolytic toxins, potentially influencing strain virulence. Twelve of the single-nucleotide variants identified in 4Q7 were probably due to the procedure used for strain construction or were present in the precursor of this strain. No sequence variants were found in pBtic235, but the distribution of the corresponding 4Q7 reads indicates a significant difference from counterparts in natural B. thuringiensis serovar israelensis strains, suggesting a duplication or over-replication in 4Q7. Thus, the 4Q7 strain is not a pure plasmid-less offshoot, but a highly genetically modified derivative of its natural ancestor. In addition to potentially influencing virulence, genome-restructuring events can modify the replication termination machinery. These findings have potential implications for the conclusions of virulence studies on 4Q7 as a model, but they also raise interesting fundamental questions about the functioning of the Bacillus genome.
Assuntos
Bacillus thuringiensis/genética , Sequências Repetidas Invertidas , Sequenciamento Completo do Genoma/métodos , Bacillus thuringiensis/classificação , Cromossomos Bacterianos/genética , Replicação do DNA , Sequenciamento de Nucleotídeos em Larga Escala , Plasmídeos/genética , Prófagos/genética , Seleção Genética , SorogrupoRESUMO
We report here the genome sequence of IL6288, a prophage-free derivative of Lactococcus lactis subsp. lactis strain IL1403, and confirm precise deletion of all prophages. Several single-nucleotide variations and an extra copy of the IS981 element, apparently having a minor influence on cell physiology, were also detected in the IL6288 genome.
RESUMO
The Bacillus cereus Group comprises organisms that are widely distributed in the environment and are of health and economic interest. We demonstrate an 'ecotypic' structure of populations in the B. cereus Group using (i) molecular data from Fluorescent Amplified Fragment Length Polymorphism patterns, ribosomal gene sequences, partial panC gene sequences, 'psychrotolerant' DNA sequence signatures and (ii) phenotypic and descriptive data from range of growth temperature, psychrotolerance and thermal niches. Seven major phylogenetic groups (I to VII) were thus identified, with ecological differences that provide evidence for a multiemergence of psychrotolerance in the B. cereus Group. A moderate thermotolerant group (VII) was basal to the mesophilic group I, from which in turn distinct thermal lineages have emerged, comprising two mesophilic groups (III, IV), an intermediate group (V) and two psychrotolerant groups (VI, II). This stepwise evolutionary transition toward psychrotolerance was particularly well illustrated by the relative abundance of the 'psychrotolerant' rrs signature (as defined by Pruss et al.) copies accumulated in strains that varied according to the phylogenetic group. The 'psychrotolerant' cspA signature (as defined by Francis et al.) was specific to group VI and provided a useful way to differentiate it from the psychrotolerant group II. This study illustrates how adaptation to novel environments by the modification of temperature tolerance limits has shaped historical patterns of global ecological diversification in the B. cereus Group. The implications for the taxonomy of this Group and for the human health risk are discussed.
Assuntos
Bacillus cereus/classificação , Adaptação Fisiológica , Bacillus cereus/fisiologia , Proteínas de Bactérias/genética , Biodiversidade , Fluorescência , Genes Bacterianos/genética , Proteínas de Choque Térmico/genética , Dados de Sequência Molecular , Polimorfismo de Fragmento de Restrição , Proteínas de Ligação a RNA/genética , Ribossomos/genética , TemperaturaRESUMO
Bacteria of the Bacillus cereus group are known to cause food poisoning. A rare phylogenetically remote strain, NVH391-98, was recently characterized to encode a particularly efficient cytotoxin K presumably responsible for food poisoning. This pathogenic strain and its close relatives can be phenotypically distinguished from other strains of the B. cereus group by the inability to grow at temperatures below 17 degrees C and by the ability to grow at temperatures from 48 to 53 degrees C. A temperate phage, phBC391A2, residing in the genome of NVH391-98 allows us to distinguish the three known members of this thermophilic strain cluster.
Assuntos
Bacillus cereus/crescimento & desenvolvimento , Citotoxinas/metabolismo , Filogenia , Temperatura , Bacillus cereus/classificação , Bacillus cereus/genética , Bacillus cereus/patogenicidade , Bacteriófagos/genética , Sequência de Bases , Análise por Conglomerados , Dados de Sequência Molecular , Análise de Sequência de DNARESUMO
The Bacillus cereus group represents sporulating soil bacteria containing pathogenic strains which may cause diarrheic or emetic food poisoning outbreaks. Multiple locus sequence typing revealed a presence in natural samples of these bacteria of about 30 clonal complexes. Application of genomic methods to this group was however biased due to the major interest for representatives closely related to Bacillus anthracis. Albeit the most important food-borne pathogens were not yet defined, existing data indicate that they are scattered all over the phylogenetic tree. The preliminary analysis of the sequences of three genomes discussed in this paper narrows down the gaps in our knowledge of the B. cereus group. The strain NVH391-98 is a rare but particularly severe food-borne pathogen. Sequencing revealed that the strain should be a representative of a novel bacterial species, for which the name Bacillus cytotoxis or Bacillus cytotoxicus is proposed. This strain has a reduced genome size compared to other B. cereus group strains. Genome analysis revealed absence of sigma B factor and the presence of genes encoding diarrheic Nhe toxin, not detected earlier. The strain B. cereus F837/76 represents a clonal complex close to that of B. anthracis. Including F837/76, three such B. cereus strains had been sequenced. Alignment of genomes suggests that B. anthracis is their common ancestor. Since such strains often emerge from clinical cases, they merit a special attention. The third strain, KBAB4, is a typical facultative psychrophile generally found in soil. Phylogenic studies show that in nature it is the most active group in terms of gene exchange. Genomic sequence revealed high presence of extra-chromosomal genetic material (about 530kb) that may account for this phenomenon. Genes coding Nhe-like toxin were found on a big plasmid in this strain. This may indicate a potential mechanism of toxicity spread from the psychrophile strain community. The results of this genomic work and ecological compartments of different strains incite to consider a necessity of creating prophylactic vaccines against bacteria closely related to NVH391-98 and F837/76. Presumably developing of such vaccines can be based on the properties of non-pathogenic strains such as KBAB4 or ATCC14579 reported here or earlier. By comparing the protein coding genes of strains being sequenced in this project to others we estimate the shared proteome, or core genome, in the B. cereus group to be 3000+/-200 genes and the total proteome, or pan-genome, to be 20-25,000 genes.
Assuntos
Bacillus cereus/genética , Microbiologia de Alimentos , Doenças Transmitidas por Alimentos/microbiologia , Genoma Bacteriano , HumanosRESUMO
Bacillus thuringiensis is a well-known biopesticide that has been used for more than 80 years. This spore-forming bacterium belongs to the group of Bacillus cereus that also includes, among others, emetic and diarrheic pathotypes of B. cereus, the animal pathogen Bacillus anthracis and the psychrotolerant Bacillus weihenstephanensis. Bacillus thuringiensis is rather unique since it has adapted its lifestyle as an efficient pathogen of specific insect larvae. One of the peculiarities of B. thuringiensis strains is the extent of their extrachromosomal pool, with strains harbouring more than 10 distinct plasmid molecules. Among the numerous serovars of B. thuringiensis, 'israelensis' is certainly emblematic since its host spectrum is apparently restricted to dipteran insects like mosquitoes and black flies, vectors of human and animal diseases such as malaria, yellow fever, or river blindness. In this review, the putative role of the mobile gene pool of B. thuringiensis serovar israelensis in its pathogenicity and dedicated lifestyle is reviewed, with specific emphasis on the nature, diversity, and potential mobility of its constituents. Variations among the few related strains of B. thuringiensis serovar israelensis will also be reported and discussed in the scope of this specialised insect pathogen, whose lifestyle in the environment remains largely unknown.
Assuntos
Bacillus thuringiensis/genética , Sequências Repetitivas Dispersas/genética , Plasmídeos/genética , Animais , Bacillus thuringiensis/patogenicidade , Variação Genética , Insetos/microbiologia , Larva/microbiologia , Especificidade da EspécieRESUMO
The lactic acid bacterium Streptococcus thermophilus is widely used for the manufacture of yogurt and cheese. This dairy species of major economic importance is phylogenetically close to pathogenic streptococci, raising the possibility that it has a potential for virulence. Here we report the genome sequences of two yogurt strains of S. thermophilus. We found a striking level of gene decay (10% pseudogenes) in both microorganisms. Many genes involved in carbon utilization are nonfunctional, in line with the paucity of carbon sources in milk. Notably, most streptococcal virulence-related genes that are not involved in basic cellular processes are either inactivated or absent in the dairy streptococcus. Adaptation to the constant milk environment appears to have resulted in the stabilization of the genome structure. We conclude that S. thermophilus has evolved mainly through loss-of-function events that remarkably mirror the environment of the dairy niche resulting in a severely diminished pathogenic potential.
Assuntos
Proteínas de Bactérias/genética , Mapeamento Cromossômico/métodos , Evolução Molecular , Instabilidade Genômica/genética , Infecções Estreptocócicas/genética , Streptococcus thermophilus/genética , Fatores de Virulência/genética , Iogurte/microbiologia , Sequência de Bases , Sequência Conservada , Genoma Bacteriano , Dados de Sequência Molecular , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico , Especificidade da Espécie , Streptococcus thermophilus/classificação , Streptococcus thermophilus/patogenicidadeRESUMO
Bacillus thuringiensis has long been recognized to carry numerous extrachromosomal molecules. Of particular interest are the strains belonging to the B. thuringiensis subsp. israelensis lineage, as they can harbor at least seven extrachromosomal molecules. One of these elements seems to be a cryptic molecule that may have been disregarded in strains considered plasmid-less. Therefore, this work focused on this cryptic molecule, named pBtic235. Using different approaches that included transposition-tagging, large plasmid gel electrophoresis and Southern blotting, conjugation and phage-induction experiments, in combination with bioinformatics analyses, it was found that pBtic235 is a hybrid molecule of 235,425 bp whose genome displays potential plasmid- and phage-like modules. The sequence of pBtic235 has been identified in all sequenced genomes of B. thuringiensis subsp. israelensis strains. Here, the pBtic235 sequence was considered identical to that of plasmid pBTHD789-2 from strain HD-789. Despite the fact that the pBtic235 genome possesses 240 putative CDSs, many of them have no homologs in the databases. However, CDSs coding for potential proteins involved in replication, genome packaging and virion structure, cell lysis, regulation of lytic-lysogenic cycles, metabolite transporters, stress and metal resistance, were identified. The candidate plasmidial prophage pBtic235 exemplifies the notable diversity of the extrachromosomal realm found in B. thuringiensis.
Assuntos
Bacillus thuringiensis/genética , Genoma Bacteriano/genética , Plasmídeos/genética , Prófagos/genética , Sequência de Bases , Conjugação Genética/fisiologia , Replicação do DNA/genética , Análise de Sequência de DNARESUMO
Bacillus thuringiensis subsp. israelensis is one of the most important microorganisms used against mosquitoes. It was intensively studied following its discovery and became a model bacterium of the B. thuringiensis species. Those studies focused on toxin genes, aggregation-associated conjugation, linear genome phages, etc. Recent announcements of genomic sequences of different strains have not been explicitly related to the biological properties studied. We report data on plasmid content analysis of four strains using ultra-high-throughput sequencing. The strains were commercial product isolates, with their putative ancestor and type B. thuringiensis subsp. israelensis strain sequenced earlier. The assembled contigs corresponding to published and novel data were assigned to plasmids described earlier in B. thuringiensis subsp. israelensis and other B. thuringiensis strains. A new 360 kb plasmid was identified, encoding multiple transporters, also found in most of the earlier sequenced strains. Our genomic data show the presence of two toxin-coding plasmids of 128 and 100 kb instead of the reported 225 kb plasmid, a co-integrate of the former two. In two of the sequenced strains, only a 100 kb plasmid was present. Some heterogeneity exists in the small plasmid content and structure between strains. These data support the perception of active plasmid exchange among B. thuringiensis subsp. israelensis strains in nature.
Assuntos
Bacillus thuringiensis/genética , Elementos de DNA Transponíveis/genética , Genoma Bacteriano/genética , Plasmídeos/genética , Animais , Bacillus thuringiensis/patogenicidade , Toxinas Bacterianas/genética , Sequência de Bases , Agentes de Controle Biológico , Culicidae/microbiologia , DNA Bacteriano/genética , Transferência Genética Horizontal/genética , Tipagem de Sequências Multilocus , Análise de Sequência de DNARESUMO
Natural transformation and viral-mediated transduction are the main avenues of horizontal gene transfer in Firmicutes. Bacillus subtilis SPP1 is a generalized transducing bacteriophage. Using this lytic phage as a model, we have analyzed how viral replication and recombination systems contribute to the transfer of plasmid-borne antibiotic resistances. Phage SPP1 DNA replication relies on essential phage-encoded replisome organizer (G38P), helicase loader (G39P), hexameric replicative helicase (G40P), recombinase (G35P) and in less extent on the partially dispensable 5'â3' exonuclease (G34.1P), the single-stranded DNA binding protein (G36P) and the Holliday junction resolvase (G44P). Correspondingly, the accumulation of linear concatemeric plasmid DNA, and the formation of transducing particles were blocked in the absence of G35P, G38P, G39P, and G40P, greatly reduced in the G34.1P, G36P mutants, and slightly reduced in G44P mutants. In contrast, establishment of injected linear plasmid DNA in the recipient host was independent of viral-encoded functions. DNA homology between SPP1 and the plasmid, rather than a viral packaging signal, enhanced the accumulation of packagable plasmid DNA. The transfer efficiency was also dependent on plasmid copy number, and rolling-circle plasmids were encapsidated at higher frequencies than theta-type replicating plasmids.
RESUMO
Genome sequence data can be used to analyze genome plasticity by whole genome PCR scanning. Small sized chromosomes can indeed be fully amplified by long-range PCR with a set of primers designed using a reference strain and applied to several other strains. Analysis of the resulting patterns can reveal the genome plasticity. To facilitate such analysis, we have developed GenoFrag, a software package for the design of primers optimized for whole genome scanning by long-range PCR. GenoFrag was developed for the analysis of Staphylococcus aureus genome plasticity by whole genome amplification in approximately 10 kb-long fragments. A set of primers was generated from the genome sequence of S.aureus N315, employed here as a reference strain. Two subsets of primers were successfully used to amplify two portions of the N315 chromosome. This experimental validation demonstrates that GenoFrag is a robust and reliable tool for primer design and that whole genome PCR scanning can be envisaged for the analysis of genome diversity in S.aureus, one of the major public health concerns worldwide.
Assuntos
Primers do DNA/genética , Genoma , Reação em Cadeia da Polimerase/métodos , Software , Pareamento de Bases , Cromossomos Bacterianos/genética , Primers do DNA/química , Genoma Bacteriano , Genômica/métodos , Hibridização de Ácido Nucleico , Sensibilidade e Especificidade , Staphylococcus aureus/classificação , Staphylococcus aureus/genética , TermodinâmicaRESUMO
Genome features of the Bacillus cereus group genomes (representative strains of Bacillus cereus, Bacillus anthracis and Bacillus thuringiensis sub spp. israelensis) were analyzed and compared with the Bacillus subtilis genome. A core set of 1381 protein families among the four Bacillus genomes, with an additional set of 933 families common to the B. cereus group, was identified. Differences in signal transduction pathways, membrane transporters, cell surface structures, cell wall, and S-layer proteins suggesting differences in their phenotype were identified. The B. cereus group has signal transduction systems including a tyrosine kinase related to two-component system histidine kinases from B. subtilis. A model for regulation of the stress responsive sigma factor sigmaB in the B. cereus group different from the well studied regulation in B. subtilis has been proposed. Despite a high degree of chromosomal synteny among these genomes, significant differences in cell wall and spore coat proteins that contribute to the survival and adaptation in specific hosts has been identified.
Assuntos
Bacillus anthracis/genética , Bacillus cereus/genética , Bacillus subtilis/genética , Bacillus thuringiensis/genética , Genoma Bacteriano , Proteínas de Bactérias/genética , Parede Celular/genética , Genômica , Glicoproteínas de Membrana/genética , Proteínas de Membrana/genética , Proteínas de Membrana Transportadoras/genética , Transdução de Sinais/genética , SinteniaRESUMO
The interaction of Al2O3 and CeO2 thin films with sulfur dioxide (2.5 mbar) or with mixtures of SO2 with O2 (5 mbar) at various temperatures (30-400 degrees C) was studied by X-ray photoelectron spectroscopy (XPS). The analysis of temperature-induced transformations of S2p spectra allowed us to identify sulfite and sulfate species and determine the conditions of their formation on the oxide surfaces. Sulfite ions, SO3(2-), which are characterized by the S2p(3/2) binding energy (BE) of approximately 167.5 eV, were shown to be formed during the interaction of the oxide films with pure SO2 at temperatures < or =200 degrees C, whereas sulfate ions, SO4(2-), with BE (S2p(3/2)) approximately 169 eV were produced at temperatures > or =300 degrees C. The formation of both the sulfite and sulfate species proceeds more efficiently in the case of CeO2. The addition of oxygen to SO2 suppresses the formation of the sulfite species on both oxides and facilitates the formation of the sulfate species. Again, this enhancement is more significant for the CeO2 film than for the Al2O3 one. The sulfation of the CeO2 film is accompanied by a reduction of Ce(IV) ions to Ce(III) ones, both in the absence and in the presence of oxygen. It has been concluded that the amount of the sulfates on the CeO2 surface treated with the SO2 + O2 mixture at > or =300 degrees C corresponds to the formation of a 3D phase of the Ce(III) sulfate. The sulfation of Al2O3 is limited by the surface of the oxide film.
RESUMO
Frankia strain R43 is a nitrogen-fixing and hydrogen-producing symbiotic actinobacterium that was isolated from nodules of Casuarina cunninghamiana but infects only Elaeagnaceae. This communication reports the genome of the strain R43 and provides insights into the microbe genomics and physiological potentials.