RESUMO
In the present work the entomopathogenic fungus B. bassiana lipids were studied against the potent pro-inflammatory and thrombotic mediators implicated in several disorders, platelet-activating factor (PAF) and thrombin. Bioactivities of lipid extracts from B. bassiana cells and culture supernatants and of their lipid fractions separated by a one-step HPLC-analysis ere assessed against the PAF/Thrombin-induced aggregation of washed rabbit platelets. Lipid extracts from both cell-biomass and supernatant inhibited strongly PAF/Thrombin-activities and platelet-aggregation, exhibiting higher specificity against PAF. Similarly, HPLC-derived lipid-fractions of phenolics/glycolipids, Sphingomyelins and Phosphatidylcholines (PC) showed strong anti-PAF potency. PC PAF-like molecules exhibited the strongest antagonistic anti-PAF effects, while in higher amounts they agonistically inhibited PAF-activities. Some bioactive lipids with strong anti-PAF effects are exo-cellularly secreted in the culture media during fungal growth, while others are not. The presence of such lipid bioactives in B. bassiana with strong anti-inflammatory and anti-thrombotic properties, provide new perspectives and putative future applications for this entomopathogenic fungus.
Assuntos
Beauveria , Animais , Anti-Inflamatórios/farmacologia , Cromatografia Líquida de Alta Pressão , Fator de Ativação de Plaquetas/farmacologia , Agregação Plaquetária , CoelhosRESUMO
BACKGROUND: Asexual fungi include important pathogens of plants and other organisms, and their effective management requires understanding of their evolutionary dynamics. Genetic recombination is critical for adaptability and could be achieved via heterokaryosis - the co-existence of genetically different nuclei in a cell resulting from fusion of non-self spores or hyphae - and the parasexual cycle in the absence of sexual reproduction. Fusion between different strains and establishment of viable heterokaryons are believed to be rare due to non-self recognition systems. Here, we investigate the extent and mechanisms of cell fusion and heterokaryosis in the important asexual plant pathogen Verticillium dahliae. RESULTS: We used live-cell imaging and genetic complementation assays of tagged V. dahliae strains to analyze the extent of non-self vegetative fusion, heterokaryotic cell fate, and nuclear behavior. An efficient CRISPR/Cas9-mediated system was developed to investigate the involvement of autophagy in heterokaryosis. Under starvation, non-self fusion of germinating spores occurs frequently regardless of the previously assessed vegetative compatibility of the partners. Supposedly "incompatible" fusions often establish viable heterokaryotic cells and mosaic mycelia, where nuclei can engage in fusion or transfer of genetic material. The molecular machinery of autophagy has a protective function against the destruction of "incompatible" heterokaryons. CONCLUSIONS: We demonstrate an imperfect function of somatic incompatibility systems in V. dahliae. These systems frequently tolerate the establishment of heterokaryons and potentially the initiation of the parasexual cycle even between strains that were previously regarded as "incompatible."
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Núcleo Celular , Hifas , Fusão Celular , FungosRESUMO
Cell-to-cell fusion is a fundamental biological process across the tree of life. In filamentous fungi, somatic fusion (or anastomosis) is required for the normal development of their syncytial hyphal networks, and it can initiate non-sexual genetic exchange processes, such as horizontal genetic transfer and the parasexual cycle. Although these could be important drivers of the evolution of asexual fungi, this remains a largely unexplored possibility due to the lack of suitable resources for their study in these puzzling organisms. We thus aimed at the characterization of cell fusion in the important asexual fungus Verticillium dahliae via Conidial Anastomosis Tubes (CATs), which can be useful for the analysis of parasexuality. We optimized appropriate procedures for their highly reproducible quantification and live-cell imaging, which were used to characterize their physiology and cell biology, and to start elucidating their underlying genetic machinery. Formation of CATs was shown to depend on growth conditions and require functional Fus3 and Slt2 MAP kinases, as well as the NADPH oxidase NoxA, whereas the GPCR Ste2 and the mating-type protein MAT1-2-1 were dispensable. We show that nuclei and other organelles can migrate through CATs, which often leads to the formation of transient dikaryons. Their nuclei have possible windows of opportunity for genetic interaction before degradation of one by a presumably homeostatic mechanism. We establish here CAT-mediated fusion in V. dahliae as an experimentally convenient system for the cytological analysis of fungal non-sexual genetic interactions. We expect that it will facilitate the dissection of sexual alternatives in asexual fungi.
Assuntos
Acremonium/genética , Proteínas Fúngicas/genética , Reprodução Assexuada/genética , Esporos Fúngicos/genética , Acremonium/patogenicidade , Ascomicetos/genética , Ascomicetos/patogenicidade , Núcleo Celular/genética , Transferência Genética Horizontal/genética , Genes Fúngicos Tipo Acasalamento/genética , Hifas/genética , Hifas/crescimento & desenvolvimento , Proteínas Quinases Ativadas por Mitógeno/genética , NADPH Oxidases/genética , Proteínas de Saccharomyces cerevisiae/genética , Esporos Fúngicos/crescimento & desenvolvimentoRESUMO
Group-I introns are widespread--though irregularly distributed--in eukaryotic organisms, and they have been extensively used for discrimination and phylogenetic analyses. Within the Verticillium genus, which comprises important phytopathogenic fungi, a group-I intron was previously identified in the SSU-rRNA (18S) gene of only V. longisporum. In this work, we aimed at elucidating the SSU-located intron distribution in V. dahliae and other Verticillium species, and the assessment of heterogeneity regarding intron content among rDNA repeats of fungal strains. Using conserved PCR primers for the amplification of the SSU gene, a structurally similar novel intron (sub-group IC1) was detected in only a few V. dahliae isolates. However, when intron-specific primers were used for the screening of a diverse collection of Verticillium isolates that originally failed to produce intron-containing SSU amplicons, most were found to contain one or both intron types, at variable rDNA repeat numbers. This marked heterogeneity was confirmed with qRT-PCR by testing rDNA copy numbers (varying from 39 to 70 copies per haploid genome) and intron copy ratios in selected isolates. Our results demonstrate that (a) IC1 group-I introns are not specific to V. longisporum within the Verticillium genus, (b) V. dahliae isolates of vegetative compatibility groups (VCGs) 4A and 6, which bear the novel intron at most of their rDNA repeats, are closely related, and (c) there is considerable intra-genomic heterogeneity for the presence or absence of introns among the ribosomal repeats. These findings underline that distributions of introns in the highly heterogeneous repetitive rDNA complex should always be verified with sensitive methods to avoid misleading conclusions for the phylogeny of fungi and other organisms.
Assuntos
Íntrons , RNA Ribossômico 18S/genética , Verticillium/genética , Sequência de Bases , Ordem dos Genes , Dados de Sequência Molecular , Conformação de Ácido Nucleico , RNA Ribossômico 18S/química , RNA Ribossômico 28S/química , RNA Ribossômico 28S/genéticaRESUMO
The genus Sidera (Hymenochaetales, Basidiomycota) comprises white-rot, mono- or dimitic fungi with poroid or hydnoid hymenophore. It has a worldwide distribution albeit with fewer species present in the Southern Hemisphere. Although recent studies revealed the existence of several new Sidera species, there are still taxonomic inconsistencies and obscure phylogenetic relationships amongst certain taxa of the genus. In this work, a large number of Sidera collections were used to obtain an updated phylogeny, based on ITS and 28S rDNA sequences by including new material from Mediterranean Europe. The monophyly of the genus was strongly supported and all species with poroid hymenophore formed a highly-supported lineage with two major subclades. In total, 23 putative species were recognised. Amongst those, five are considered to possibly represent entities new to science, but further work is required since they are represented by single specimens or environmental sequences. Examined collections originally named S.lenis from southern Europe were grouped within S.vulgaris. Similarly, several collections under various names were hereby identified as S.vulgaris, including those of the recently described species S.tibetica. Furthermore, a critical discussion (based on morphoanatomical findings) is made on the key features that could be used to distinguish S.lenis from S.vulgaris.
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Filamentous fungi can sense useful resources and hazards in their environment and direct growth of their hyphae accordingly. Chemotropism ensures access to nutrients, contact with other individuals (e.g., for mating), and interaction with hosts in the case of pathogens. Previous studies have revealed a complex chemotropic sensing landscape during host-pathogen interactions, but the underlying molecular machinery remains poorly characterized. Here we studied mechanisms controlling directed hyphal growth of the important plant-pathogenic fungus Verticillium dahliae towards different chemoattractants. We found that the homologs of the Rag GTPase Gtr1 and the GTPase-activating protein Tsc2, an activator and a repressor of the TOR kinase respectively, play important roles in hyphal chemotropism towards nutrients, plant-derived signals, and heterologous α-pheromone of Fusarium oxysporum. Furthermore, important roles of these regulators were identified in fungal development and pathogenicity. We also found that the mitogen-activated protein kinase (MAPK) Fus3 is required for chemotropism towards nutrients, while the G protein-coupled receptor (GPCR) Ste2 and the MAPK Slt2 control chemosensing of plant-derived signals and α-pheromone. Our study establishes V. dahliae as a suitable model system for the analysis of fungal chemotropism and discovers new components of chemotropic signaling during growth and host-pathogen interactions of V. dahliae.
Assuntos
Ascomicetos , Verticillium , Humanos , Virulência , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Ascomicetos/metabolismo , Feromônios/metabolismo , Proteínas Fúngicas/metabolismo , Doenças das PlantasRESUMO
The enzymatic arsenal of several soil microorganisms renders them particularly suitable for the degradation of lignocellulose, a process of distinct ecological significance with promising biotechnological implications. In this study, we investigated the spatiotemporal diversity and distribution of bacteria and fungi with 16S and Internally Trascribed Spacer (ITS) ribosomal RNA next-generation-sequencing (NGS), focusing on forest mainland Abies cephalonica and insular Quercus ilex habitats of Greece. We analyzed samples during winter and summer periods, from different soil depths, and we applied optimized and combined targeted meta-omics approaches aiming at the peroxidase-catalase family enzymes to gain insights into the lignocellulose degradation process at the soil microbial community level. The microbial communities recorded showed distinct patterns of response to season, soil depth and vegetation type. Overall, in both forests Proteobacteria, Actinobacteria, Acidobacteria were the most abundant bacteria phyla, while the other phyla and the super-kingdom of Archaea were detected in very low numbers. Members of the orders Agaricales, Russulales, Sebacinales, Gomphales, Geastrales, Hysterangiales, Thelephorales, and Trechisporales (Basidiomycota), and Pezizales, Sordariales, Eurotiales, Pleosporales, Helotiales, and Diaporthales (Ascomycota) were the most abundant for Fungi. By using optimized "universal" PCR primers that targeted the peroxidase-catalase enzyme family, we identified several known and novel sequences from various Basidiomycota, even from taxa appearing at low abundance. The majority of the sequences recovered were manganese peroxidases from several genera of Agaricales, Hysterangiales, Gomphales, Geastrales, Russulales, Hymenochaetales, and Trechisporales, while lignin -and versatile-peroxidases were limited to two to eight species, respectively. Comparisons of the obtained sequences with publicly available data allowed a detailed structural analysis of polymorphisms and functionally relevant amino-acid residues at phylogenetic level. The targeted metagenomics applied here revealed an important role in lignocellulose degradation of hitherto understudied orders of Basidiomycota, such as the Hysterangiales and Gomphales, while it also suggested the auxiliary activity of particular members of Proteobacteria, Actinobacteria, Acidobacteria, Verrucomicrobia, and Gemmatimonadetes. The application of NGS-based metagenomics approaches allows a better understanding of the complex process of lignocellulolysis at the microbial community level as well as the identification of candidate taxa and genes for targeted functional investigations and genetic modifications.
RESUMO
Zymomonas mobilis is an ethanologenic bacterium that has been studied for use in biofuel production. Of the sequenced Zymomonas strains, ATCC 29191 has been described as the phenotypic centrotype of Zymomonas mobilis subsp. mobilis, the taxon that harbors the highest ethanol-producing Z. mobilis strains. ATCC 29191 was isolated in Kinshasa, Congo, from palm wine fermentations. This strain is reported to be a robust levan producer, while in recent years it has been employed in studies addressing Z. mobilis respiration. Here we announce the finishing and annotation of the ATCC 29191 genome, which comprises one chromosome and three plasmids.
Assuntos
DNA Bacteriano/química , DNA Bacteriano/genética , Etanol/metabolismo , Genoma Bacteriano , Análise de Sequência de DNA , Zymomonas/genética , Zymomonas/metabolismo , Congo , Fermentação , Frutanos/metabolismo , Redes e Vias Metabólicas , Dados de Sequência Molecular , Oxirredução , Plasmídeos , Vinho/microbiologia , Zymomonas/isolamento & purificaçãoRESUMO
Zymomonas mobilis ATCC 10988 is the type strain of the Z. mobilis subsp. mobilis taxon, members of which are some of the most rigorous ethanol-producing bacteria. Isolated from Agave cactus fermentations in Mexico, ATCC 10988 is one of the first Z. mobilis strains to be described and studied. Its robustness in sucrose-substrate fermentations, physiological characteristics, large number of plasmids, and overall genomic plasticity render this strain important to the study of the species. Here we report the finishing and annotation of the ATCC 10988 chromosomal and plasmid genome.
Assuntos
DNA Bacteriano/química , DNA Bacteriano/genética , Genoma Bacteriano , Análise de Sequência de DNA , Zymomonas/genética , Agave/microbiologia , Etanol/metabolismo , Fermentação , Microbiologia de Alimentos , México , Dados de Sequência Molecular , Plasmídeos , Sacarose/metabolismo , Zymomonas/isolamento & purificação , Zymomonas/metabolismo , Zymomonas/fisiologiaRESUMO
Zymomonas mobilis is an alphaproteobacterium studied for bioethanol production. Different strains of this organism have been hitherto sequenced; they all belong to the Z. mobilis subsp. mobilis taxon. Here we report the finished and annotated genome sequence of strain ATCC 29192, a cider-spoiling agent isolated in the United Kingdom. ATCC 29192 is the lectotype of the second-best-characterized subspecies of Z. mobilis, Z. mobilis subsp. pomaceae. The nucleotide sequence of ATCC 29192 deviates from that of Z. mobilis subsp. mobilis representatives, which justifies its distinct taxonomic positioning and proves particularly useful for comparative and functional genomic analyses.
Assuntos
DNA Bacteriano/química , DNA Bacteriano/genética , Genoma Bacteriano , Análise de Sequência de DNA , Zymomonas/genética , Etanol/metabolismo , Microbiologia de Alimentos , Dados de Sequência Molecular , Reino Unido , Zymomonas/isolamento & purificação , Zymomonas/metabolismoRESUMO
The potential genotoxic effects of several pure secondary metabolites produced by fungi used as biological control agents (BCAs) were studied with the Ames Salmonella/microsome mutagenicity assay and the Vitotox test, with and without metabolic activation. A complete set of Salmonella tester strains was used to avoid false negative results. To detect possible mutagenic and/or cytotoxic effects of fungal secondary metabolites due to synergistic action, crude extracts and fungal cell extracts of the BCAs were also examined. Although the sensitivity of the methods varied depending on the metabolite used, clearly no genotoxicity was observed in all cases. The results of the two assays are discussed in the light of being used in a complementary fashion for a convincing risk-assessment evaluation of fungal BCAs and their secondary metabolites.
Assuntos
Fungos/metabolismo , Testes de Mutagenicidade/métodos , Mutagênicos/toxicidade , Micotoxinas/toxicidade , Controle Biológico de Vetores , Micotoxinas/metabolismo , Salmonella typhimurium/genéticaRESUMO
Maintenance of redox homeostasis is vital for aerobic organisms and particularly relevant to plant pathogens. A balance is required between their endogenous ROS production, which is important for their development and pathogenicity, and host-derived oxidative stress. Endogenous ROS in fungi are generated by membrane-bound NADPH oxidase (NOX) complexes and the mitochondrial respiratory chain, while transcription factor Yap1 is a major regulator of the antioxidant response. Here, we investigated the roles of NoxA and Yap1 in fundamental biological processes of the important plant pathogen Verticillium dahliae. Deletion of noxA impaired growth and morphogenesis, compromised formation of hyphopodia, diminished penetration ability and pathogenicity, increased sensitivity against antifungal agents, and dysregulated expression of antioxidant genes. On the other hand, deletion of yap1 resulted in defects in conidial and microsclerotia formation, increased sensitivity against oxidative stress, and down-regulated antioxidant genes. Localized accumulation of ROS was observed before conidial fusion and during the heterokaryon incompatibility reaction upon nonself fusion. The frequency of inviable fusions was not affected by the deletion of Yap1. Analysis of a double knockout mutant revealed an epistatic relationship between noxA and yap1. Our results collectively reveal instrumental roles of NoxA and ROS homeostasis in the biology of V. dahliae.
RESUMO
BACKGROUND: The entomopathogenic fungi of the genus Beauveria are cosmopolitan with a variety of different insect hosts. The two most important species, B. bassiana and B. brongniartii, have already been used as biological control agents of pests in agriculture and as models for the study of insect host - pathogen interactions. Mitochondrial (mt) genomes, due to their properties to evolve faster than the nuclear DNA, to contain introns and mobile elements and to exhibit extended polymorphisms, are ideal tools to examine genetic diversity within fungal populations and genetically identify a species or a particular isolate. Moreover, mt intergenic region can provide valuable phylogenetic information to study the biogeography of the fungus. RESULTS: The complete mt genomes of B. bassiana (32,263 bp) and B. brongniartii (33,920 bp) were fully analysed. Apart from a typical gene content and organization, the Beauveria mt genomes contained several introns and had longer intergenic regions when compared with their close relatives. The phylogenetic diversity of a population of 84 Beauveria strains -mainly B. bassiana (n = 76) - isolated from temperate, sub-tropical and tropical habitats was examined by analyzing the nucleotide sequences of two mt intergenic regions (atp6-rns and nad3-atp9) and the nuclear ITS1-5.8S-ITS2 domain. Mt sequences allowed better differentiation of strains than the ITS region. Based on mt and the concatenated dataset of all genes, the B. bassiana strains were placed into two main clades: (a) the B. bassiana s. l. and (b) the "pseudobassiana". The combination of molecular phylogeny with criteria of geographic and climatic origin showed for the first time in entomopathogenic fungi, that the B. bassiana s. l. can be subdivided into seven clusters with common climate characteristics. CONCLUSIONS: This study indicates that mt genomes and in particular intergenic regions provide molecular phylogeny tools that combined with criteria of geographic and climatic origin can subdivide the B. bassiana s.l. entomopathogenic fungi into seven clusters with common climate characteristics.
Assuntos
Beauveria/genética , DNA Intergênico/genética , DNA Mitocondrial/genética , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica/fisiologia , Biblioteca Gênica , Dados de Sequência Molecular , FilogeniaRESUMO
The expression of laccase and manganese peroxidase genes of a selected strain of Pleurotus ostreatus were studied in olive oil mill wastewater (OMW). The fungal strain decolourized 50% OMW in a linear way for 21 days and, at the same time, degraded the phenol compounds by 85%. Transcripts of laccase genes poxa1b, pox2, poxa3, and sspoxa3a, sspoxa3b coding for the small subunits of POXA3, were estimated by qRT-PCR, at different time intervals, together with beta-tubulin gene used as internal control, from fungal cultures grown in a chemically-defined complete medium (CM), a supplemented CM with the addition of Cu(+2) and Mn(+2) (CM-plus) and 50% OMW in distilled water. The most abundant transcripts in both OMW and CM-plus were those of the poxa3, whereas pox2 transcripts were induced only in OMW and those of poxa1b at a strict time-window (14 days) in both OMW and CM-plus. Interestingly enough, the transcripts of genes sspoxa3a and sspoxa3b were up-regulated between 14-21 days, at a time at which the large subunit of the enzyme coded by poxa3 was down-regulated. The manganese peroxidase gene mnp2 exhibited a strong and specific transcriptional induction in OMW after 12 and 14 days, followed by a drastic drop after 18 days and a complete cease of expression at day 21, whereas mnp3 transcripts were at maximum level in OMW at day 10 but where thereafter reduced.
Assuntos
Regulação Enzimológica da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Resíduos Industriais , Lacase/genética , Lignina/metabolismo , Peroxidases/genética , Óleos de Plantas/metabolismo , Pleurotus/enzimologia , Pleurotus/crescimento & desenvolvimento , Eliminação de Resíduos Líquidos , Meios de Cultura , Perfilação da Expressão Gênica , Azeite de Oliva , Pleurotus/genéticaRESUMO
Ganoderma P. Karst. is a cosmopolitan genus of white-rot fungi which comprises species with highly-prized pharmaceutical properties, valuable biotechnological applications and of significant phytopathological interest. However, the status of the taxonomy within the genus is still highly controversial and ambiguous despite the progress made through molecular approaches. A metadata analysis of 3908 nuclear ribosomal internal transcribed spacer (ITS) rDNA sequences obtained from GenBank/ENA/DDBJ and UNITE was performed by targeting sequences annotated as Ganoderma, but also sequences from environmental samples and from material examined for the first time. Ganoderma taxa segregated into five main lineages (Clades A to E). Clade A corresponds to the core of laccate species and includes G. shanxiense and three major well-supported clusters: Cluster A.1 ('G. lucidum sensu lato') consists of taxa from Eurasia and North America, Cluster A.2 of material with worldwide occurrence including G. resinaceum and Cluster A.3 is composed of species originating from all continents except Europe and comprises G. lingzhi. Clade B includes G. applanatum and allied species with a Holarctic distribution. Clade C comprises taxa from Asia and Africa only. Clade D consists of laccate taxa with tropical/subtropical occurrence, while clade E harbours the highest number of non-laccate species with a cosmopolitan distribution. The 92 Ganoderma-associated names, initially used for sequences labelling, correspond to at least 80 taxa. Amongst them, 21 constitute putatively new phylospecies after our application of criteria relevant to the robustness/support of the terminal clades, intra- and interspecific genetic divergence and available biogeographic data. Moreover, several other groups or individual sequences seem to represent distinct taxonomic entities and merit further investigation. A particularly large number of the public sequences was revealed to be insufficiently and/or incorrectly identified, for example, 87% and 78% of entries labelled as G. australe and G. lucidum, respectively. In general, ITS demonstrated high efficacy in resolving relationships amongst most of the Ganoderma taxa; however, it was not equally useful at elucidating species barriers across the entire genus and such cases are outlined. Furthermore, we draw conclusions on biogeography by evaluating species occurrence on a global scale in conjunction with phylogenetic structure/patterns. The sequence variability assessed in ITS spacers could be further exploited for diagnostic purposes.
RESUMO
Woronin bodies are membrane-bound organelles of filamentous ascomycetes that mediate hyphal compartmentalization by plugging septal pores upon hyphal damage. Their major component is the peroxisomal protein Hex1, which has also been implicated in additional cellular processes in fungi. Here, we analyzed the Hex1 homolog of Verticillium dahliae, an important asexual plant pathogen, and we report its pleiotropic involvement in fungal growth, physiology, stress response, and pathogenicity. Alternative splicing of the Vdhex1 gene can lead to the production of two Hex1 isoforms, which are structurally similar to their Neurospora crassa homolog. We show that VdHex1 is targeted to the septum, consistently with its demonstrated function in sealing hyphal compartments to prevent excessive cytoplasmic bleeding upon injury. Furthermore, our investigation provides direct evidence for significant contributions of Hex1 in growth and morphogenesis, as well as in asexual reproduction capacity. We discovered that Hex1 is required both for normal responses to osmotic stress and factors that affect the cell wall and plasma-membrane integrity, and for normal resistance to oxidative stress and reactive oxygen species (ROS) homeostasis. The Vdhex1 mutant exhibited diminished ability to colonize and cause disease on eggplant. Overall, we show that Hex1 has fundamentally important multifaceted roles in the biology of V. dahliae.
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Zymomonas mobilis is an ethanol-producing alphaproteobacterium currently considered a major candidate organism for bioethanol production. Here we report the finished and annotated genome sequence of Z. mobilis subsp. mobilis strain NCIMB 11163, a British ale-infecting isolate. This is the first Z. mobilis strain whose genome, chromosomal and plasmid, is presented in its entirety.
Assuntos
Etanol/metabolismo , Genoma Bacteriano/genética , Zymomonas/genética , Zymomonas/metabolismo , Cromossomos Bacterianos/genética , Dados de Sequência Molecular , Fases de Leitura Aberta/genética , Análise de Sequência de DNARESUMO
Methicillin-resistant Staphylococcus aureus (MRSA) strains are important human pathogens and a significant health hazard for hospitals and the food industry. They are resistant to ß-lactam antibiotics including methicillin and extremely difficult to treat. In this study, we show that the Staphylococcus aureus COL (MRSA) strain, with a known complete genome, can easily survive and grow under acidic and alkaline conditions (pH5 and pH9, respectively), both planktonically and as a biofilm. A microarray-based analysis of both planktonic and biofilm cells was performed under acidic and alkaline conditions showing that several genes are up- or down-regulated under different environmental conditions and growth modes. These genes were coding for transcription regulators, ion transporters, cell wall biosynthetic enzymes, autolytic enzymes, adhesion proteins and antibiotic resistance factors, most of which are associated with biofilm formation. These results will facilitate a better understanding of the physiological adjustments occurring in biofilm-associated S. aureus COL cells growing in acidic or alkaline environments, which will enable the development of new efficient treatment or disinfection strategies.
RESUMO
The complete mitochondrial DNA (mtDNA) sequence was determined for the phytopathogenic fungus Fusarium oxysporum. It is 34,477 bp long, maps circularly, and encodes for 14 protein-coding, 25 tRNA and 2 rRNA genes. The nucleotide and amino acid data sets from its 14 concatenated protein-coding mitochondrial (mt) genes were used along with gene order comparisons for an extensive phylogenetic study of the Subphylum Pezizomycotina. Our results are in agreement with current taxonomic treatments and additionally provide better statistical support for all relationships within Pezizomycotina when compared to analyses based on single or few gene data sets. The gene order of F. oxysporum was consistent with that established in the order Hypocreales (Class: Sordariomycetes) and enhanced previous suppositions on the ancestral state of Sordariomycetes. In comparison with mt genomes of the other orders it added further insights to the evolution of Pezizomycotina.
Assuntos
Fusarium/genética , Genoma Mitocondrial , Códon , DNA Intergênico/química , DNA Mitocondrial/química , Evolução Molecular , Fusarium/classificação , Ordem dos Genes , Genes Fúngicos , FilogeniaRESUMO
The emergence of methicillin-resistant Staphylococcus aureus (MRSA) in food has provoked a great concern about the presence of MRSA in associated foodstuff. Although MRSA is often detected in various retailed meat products, it seems that food handlers are more strongly associated with this type of food contamination. Thus, it can be easily postulated that any food could be contaminated with this pathogen in an industrial environment or in household and cause food poisoning. To this direction, the effect of rocket (Eruca sativa) extract on MRSA growth and proteome was examined in the present study. This goal was achieved with the comparative study of the MRSA strain COL proteome, cultivated in rocket extract versus the standard Luria-Bertani growth medium. The obtained results showed that MRSA was able to grow in rocket extract. In addition, proteome analysis using 2-DE method showed that MRSA strain COL is taking advantage of the sugar-, lipid-, and vitamin-rich substrate in the liquid rocket extract, although its growth was delayed in rocket extract compared to Luria-Bertani medium. This work could initiate further research about bacterial metabolism in plant-based media and defense mechanisms against plant-derived antibacterials.