RESUMO
In this study, two strains of Bdellovibrio were isolated from soil samples using the culture-dependent technique and two members of the family Enterobacteriaceae (Klebsiella sp. and Salmonella sp.) as prey. The Bdellovibrio strains were bacteriolytic, plaque-forming, and highly motile gram-negative bacteria. We identified and confirmed the Bdellovibrio strains using microscopy, PCR amplification, and sequencing of the 16S rRNA gene. They were observed to be different strains based on hit locus and prey range analyses. Here, the first report on Bdellovibrio strains isolated from soil in Mexico corroborates earlier report indicating that populations of Bdellovibrio found in soil are heterogeneous thereby the need to identify the various strains.
Assuntos
Bacteriólise/fisiologia , Bdellovibrio/isolamento & purificação , Agentes de Controle Biológico/metabolismo , Klebsiella/crescimento & desenvolvimento , Salmonella/crescimento & desenvolvimento , Sequência de Bases , Bdellovibrio/classificação , Bdellovibrio/genética , DNA Bacteriano/genética , México , Microscopia de Força Atômica , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Microbiologia do SoloRESUMO
Type IV secretion systems (T4SSs) are multiprotein complexes that transport effector proteins and protein-DNA complexes through bacterial membranes to the extracellular milieu or directly into the cytoplasm of other cells. Many bacteria of the family Xanthomonadaceae, which occupy diverse environmental niches, carry a T4SS with unknown function but with several characteristics that distinguishes it from other T4SSs. Here we show that the Xanthomonas citri T4SS provides these cells the capacity to kill other Gram-negative bacterial species in a contact-dependent manner. The secretion of one type IV bacterial effector protein is shown to require a conserved C-terminal domain and its bacteriolytic activity is neutralized by a cognate immunity protein whose 3D structure is similar to peptidoglycan hydrolase inhibitors. This is the first demonstration of the involvement of a T4SS in bacterial killing and points to this special class of T4SS as a mediator of both antagonistic and cooperative interbacterial interactions.
Assuntos
Antibiose/fisiologia , Proteínas de Bactérias/metabolismo , Bacteriólise/fisiologia , Modelos Moleculares , Sistemas de Secreção Tipo IV/metabolismo , Xanthomonas/fisiologia , Proteínas de Bactérias/imunologia , Clonagem Molecular , Cristalização , Escherichia coli , Immunoblotting , Imunoprecipitação , Microscopia de Fluorescência , Conformação Proteica , Espalhamento a Baixo Ângulo , Sistemas de Secreção Tipo IV/química , Difração de Raios X , Xanthomonas/metabolismoRESUMO
Some clinical isolates of Pseudomonas aeruginosa stored in our culture collection did not grow or grew poorly and showed lysis on the culture plates when removed from the collection and inoculated on MacConkey agar. One hypothesis was that bacteriophages had infected and killed those clinical isolates. To check the best storage conditions to maintain viable P. aeruginosa for a longer time, clinical isolates were stored at various temperatures and were grown monthly. We investigated the presence of phage in 10 clinical isolates of P. aeruginosa stored in our culture collection. Four strains of P. aeruginosa were infected by phages that were characterized by electron microscopy and isolated to assess their ability to infect. The best condition to maintain the viability of the strains during storage was in water at room temperature. Three Siphoviridae and two Myoviridae phages were visualized and characterized by morphology. We confirmed the presence of bacteriophages infecting clinical isolates, and their ability to infect and lyse alternative hosts. Strain PAO1, however, did not show lysis to any phage. Mucoid and multidrug resistant strains of P. aeruginosa showed lysis to 50% of the phages tested.
Assuntos
Bacteriólise/fisiologia , Bacteriófagos/isolamento & purificação , Pseudomonas aeruginosa/virologia , Técnicas Bacteriológicas , Bacteriófagos/ultraestrutura , Bancos de Espécimes Biológicos , Meios de Cultura , Farmacorresistência Bacteriana Múltipla , Humanos , Microscopia Eletrônica , Myoviridae/isolamento & purificação , Pseudomonas aeruginosa/classificação , Pseudomonas aeruginosa/isolamento & purificação , Siphoviridae/isolamento & purificação , Ensaio de Placa Viral , VirulênciaRESUMO
Some clinical isolates of Pseudomonas aeruginosa stored in our culture collection did not grow or grew poorly and showed lysis on the culture plates when removed from the collection and inoculated on MacConkey agar. One hypothesis was that bacteriophages had infected and killed those clinical isolates. To check the best storage conditions to maintain viable P. aeruginosa for a longer time, clinical isolates were stored at various temperatures and were grown monthly. We investigated the presence of phage in 10 clinical isolates of P. aeruginosa stored in our culture collection. Four strains of P. aeruginosa were infected by phages that were characterized by electron microscopy and isolated to assess their ability to infect. The best condition to maintain the viability of the strains during storage was in water at room temperature. Three Siphoviridae and two Myoviridae phages were visualized and characterized by morphology. We confirmed the presence of bacteriophages infecting clinical isolates, and their ability to infect and lyse alternative hosts. Strain PAO1, however, did not show lysis to any phage. Mucoid and multidrug resistant strains of P. aeruginosa showed lysis to 50% of the phages tested.
Assuntos
Humanos , Bacteriólise/fisiologia , Bacteriófagos/isolamento & purificação , Pseudomonas aeruginosa/virologia , Técnicas Bacteriológicas , Bancos de Espécimes Biológicos , Bacteriófagos/ultraestrutura , Meios de Cultura , Farmacorresistência Bacteriana Múltipla , Microscopia Eletrônica , Myoviridae/isolamento & purificação , Pseudomonas aeruginosa/classificação , Pseudomonas aeruginosa/isolamento & purificação , Siphoviridae/isolamento & purificação , Ensaio de Placa Viral , VirulênciaRESUMO
AIMS: Frequency of lysogeny in Lactobacillus delbrueckii strains (from commercial and natural starters) and preliminary characterization of temperate bacteriophages isolated from them. METHODS AND RESULTS: Induction of strains (a total of 16) was made using mitomycin C (MC) (0.5 mug ml(-1)). For 37% of the MC-treated supernatants, it was possible to detect phage particles or presence of killing activity, but only two active bacteriophages were isolated. The two temperate phages isolated were prolate-headed phages which belonged to group c of Lact. delbrueckii bacteriophages classification. Different DNA restriction patterns were obtained for each phage, while the structural protein profiles and packaging sites were identical. Distinctive one-step growth curves were exhibited by each phage. An influence of calcium ions was observed for their lysis in broth but not on the adsorption levels. CONCLUSIONS: Our study showed that lysogeny is also present in Lact. delbrueckii strains, including commercial strains. SIGNIFICANCE AND IMPACT OF THE STUDY: Commercial strains could be lysogenic and this fact has a great practical importance since they could contribute to the dissemination of active-phage particles in industrial environments.
Assuntos
Bacteriófagos/fisiologia , Lactobacillus delbrueckii/virologia , Lisogenia/fisiologia , Bacteriólise/fisiologia , Bacteriófagos/genética , Bacteriófagos/ultraestrutura , Cálcio/farmacologia , DNA Viral/genética , DNA Viral/isolamento & purificação , Lactobacillus delbrueckii/fisiologia , Microscopia Eletrônica , Mapeamento por Restrição , Proteínas Virais/genéticaRESUMO
Structural studies by in-cell nuclear magnetic resonance are a developing new field of research, and their objective is to obtain structural information of proteins and other biological macromolecules in the cytoplasm of Escherichia coli cells. The major limitation of in-cell experiments is cell lysis that occurs during the experiments. In this article, we describe how inhibition of autologous expression by rifampicin at a high concentration decreases cell lysis in E. coli. We suggest that rifampicin is acting in the programmed cell death gene system MazEF, which is triggered by stress conditions and ultimately leads to cell lysis.
Assuntos
Bacteriólise/fisiologia , Proteínas de Escherichia coli/antagonistas & inibidores , Escherichia coli/efeitos dos fármacos , Escherichia coli/metabolismo , Ressonância Magnética Nuclear Biomolecular/métodos , Bacteriólise/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Morte Celular/fisiologia , Citoplasma/metabolismo , Proteínas de Ligação a DNA/efeitos dos fármacos , Proteínas de Ligação a DNA/metabolismo , Escherichia coli/citologia , Proteínas de Escherichia coli/efeitos dos fármacos , Proteínas de Escherichia coli/metabolismo , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Genes Bacterianos/efeitos dos fármacos , Rifampina/farmacologia , Tiorredoxinas/análiseRESUMO
As a strategy to augment the potential of existing drugs against Mycobacterium avium we investigated a mycobacteriolytic preparation (stazyme) from the Staphylococcus strain Clavelis, which results in significant mycobacterial growth inhibition. A total of 10 specific protein bands were characterized in the stazyme preparation: three bands within a major 40-60 kDa fraction, five bands within the range of 30-90 kDa, and two bands of about 12 and 14 kDa respectively. Tested at concentrations of 50 and 200 microg ml(-1) of total protein, stazyme was highly bactericidal against M. smegmatis, and bacteriostatic against M. tuberculosis and M. avium. Stazyme was able to break the permeability barrier of M. avium isolates, significantly enhancing the activity of other antituberculous drugs (ethambutol, rifampicin, and amikacin), used at sub-MIC level. Stazyme essentially possessed a lytic activity as evidenced by its ability to lyse purified M. smegmatis cell walls. This lytic activity was also confirmed on intact M. smegmatis and M. avium bacilli by transmission electron microscopy. Precise identification of this mycobacteriolytic determinant(s) in stazyme may be helpful to define novel drug targets in mycobacteria.