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1.
Sci Rep ; 6: 31749, 2016 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-27526944

RESUMO

Salivaricin B is a 25 amino acid polycyclic peptide belonging to the type AII lantibiotics and first shown to be produced by Streptococcus salivarius. In this study we describe the bactericidal mode of action of salivaricin B against susceptible Gram-positive bacteria. The killing action of salivaricin B required micro-molar concentrations of lantibiotic whereas the prototype lantibiotic nisin A was shown to be potent at nano-molar levels. Unlike nisin A, salivaricin B did not induce pore formation or dissipate the membrane potential in susceptible cells. This was established by measuring the fluorescence of the tryptophan residue at position 17 when salivaricin B interacted with bacterial membrane vesicles. The absence of a fluorescence blue shift indicates a failure of salivaricin B to penetrate the membranes. On the other hand, salivaricin B interfered with cell wall biosynthesis, as shown by the accumulation of the final soluble cell wall precursor UDP-MurNAc-pentapeptide which is the backbone of the bacterial peptidoglycan. Transmission electron microscopy of salivaricin B-treated cells showed a reduction in cell wall thickness together with signs of aberrant septum formation in the absence of visible changes to cytoplasmic membrane integrity.


Assuntos
Antibacterianos/farmacologia , Bacteriocinas/farmacologia , Bactérias Gram-Positivas/efeitos dos fármacos , Sequência de Aminoácidos , Antibacterianos/química , Proteínas de Bactérias/química , Proteínas de Bactérias/farmacologia , Bacteriocinas/química , Parede Celular/efeitos dos fármacos , Parede Celular/ultraestrutura , Bactérias Gram-Positivas/ultraestrutura , Testes de Sensibilidade Microbiana , Micrococcus luteus/efeitos dos fármacos , Micrococcus luteus/ultraestrutura , Microscopia Eletrônica de Transmissão , Streptococcus pyogenes/efeitos dos fármacos , Streptococcus pyogenes/ultraestrutura
2.
Biomacromolecules ; 15(9): 3440-8, 2014 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-25100636

RESUMO

Cellulose beads with ∼3 mm of diameter and high circularity were obtained by dripping cellulose solutions (5, 6, and 7 wt %) dissolved in NaOH7%/urea12%, into HCl 2 M coagulation bath. Carboxylic groups were generated on beads surface through NaClO/NaClO2/TEMPO oxidation method, achieving total charge density of ∼0.77 mmol/g. Pristine (CB) and oxidized (OCB) beads were characterized by means of optical images analyses, scanning electron microscopy (SEM) and compression tests. Both types of beads, CB and OCB, were used as adsorbent for poly(4-vinyl-N-pentylpyridinium) bromide, QPVP-C5, a bactericidal agent. The adsorption of QPVP-C5 on CB and OCB was evaluated by means of FTIR-ATR, UV-vis, CHN elemental analyses, and X-ray photoelectron spectroscopy (XPS). The adsorbed amount of QPVP-C5 was remarkably higher on OCB than on CB due to ionic interactions. Desorption was less than 5%. The interaction between neat OCB or OCB coated and two different amounts of QPVP-C5 and Gram-positive bacteria Micrococcus luteus was assessed by changes in turbidimetry, SEM, and elemental analyses. Bacteria adsorbed on the surface of neat OCB and weakly QPVP-C5 coated OCB due to hydrogen bonding or ion-dipole interaction. Notorious bactericidal action was observed for OCB samples coated with large amount of QPVP-C5.


Assuntos
Celulose/química , Micrococcus luteus/química , Microesferas , Adsorção , Celulose/ultraestrutura , Micrococcus luteus/ultraestrutura , Oxirredução , Percloratos/química , Espectroscopia Fotoeletrônica , Compostos de Sódio/química , Espectroscopia de Infravermelho com Transformada de Fourier
3.
Bioresour Technol ; 126: 233-7, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23073113

RESUMO

Micrococcus luteus DE2008 has the ability to absorb lead and copper. The effect of these metals on biomass and viability of this microorganism were investigated and removal of the metals from culture media was determined. Lead had no effect on the biomass expressed as mg Carbon/cm(3) of M. Iuteus DE2008, but in the case of copper, the minimum metal concentration that affected the biomass was 0.1 mM Cu(II). According to these results this microorganism shows a greater tolerance for lead. The minimum metal concentration that affected viability (expressed as the percentage of live cells) was 0.5 mM for both metals. M. luteus DE2008 exhibited a specific removal capacity of 408 mg/g for copper and 1965 mg/g for lead. This microorganism has a greater ability to absorb Pb(II) than Cu(II). M. luteus DE2008 could be seen as a microorganism capable of restoring environments polluted by lead and copper.


Assuntos
Adaptação Fisiológica , Cobre/isolamento & purificação , Micrococcus luteus/metabolismo , Zinco/isolamento & purificação , Adsorção , Biodegradação Ambiental , Biomassa , Biopolímeros/química , Cobre/toxicidade , Espaço Extracelular/química , Viabilidade Microbiana , Micrococcus luteus/citologia , Micrococcus luteus/crescimento & desenvolvimento , Micrococcus luteus/ultraestrutura , Zinco/toxicidade
4.
Colloids Surf B Biointerfaces ; 67(1): 32-40, 2008 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-18815013

RESUMO

Bacterial biofilms were imaged by atomic force microscopy (AFM), and their elasticity and adhesion to the AFM tip were determined from a series of tip extension and retraction cycles. Though the five bacterial strains studied included both Gram-negative and -positive bacteria and both environmental and laboratory strains, all formed simple biofilms on glass surfaces. Cellular spring constants, determined from the extension portion of the force cycle, varied between 0.16+/-0.01 and 0.41+/-0.01 N/m, where larger spring constants were measured for Gram-positive cells than for Gram-negative cells. The nonlinear regime in the extension curve depended upon the biomolecules on the cell surface: the extension curves for the smooth Gram-negative bacterial strains with the longest lipopolysaccharides on their surface had a larger nonlinear region than the rough bacterial strain with shorter lipopolysaccharides on the surface. Adhesive forces between the retracting silicon nitride tip and the cells varied between cell types in terms of the force components, the distance components, and the number of adhesion events. The Gram-negative cells' adhesion to the tip showed the longest distance components, sometimes more than 1 microm, whereas the shortest distance adhesion events were measured between the two Gram-positive cell types and the tip. Fixation of free-swimming planktonic cells by NHS and EDC perturbed both the elasticity and the adhesive properties of the cells. Here we consider the biochemical meaning of the measured physical properties of simple biofilms and implications to the colonization of surfaces in the first stages of biofilm formation.


Assuntos
Aderência Bacteriana/fisiologia , Biofilmes , Elasticidade/fisiologia , Microscopia de Força Atômica , Bacillus subtilis/fisiologia , Bacillus subtilis/ultraestrutura , Escherichia coli/fisiologia , Escherichia coli/ultraestrutura , Micrococcus luteus/fisiologia , Micrococcus luteus/ultraestrutura , Pseudomonas putida/fisiologia , Pseudomonas putida/ultraestrutura
5.
J Biomed Mater Res B Appl Biomater ; 80(1): 211-9, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16850477

RESUMO

This study investigated the bacterial inactivation/sterilization effects of a new atmospheric plasma source, which is a brush-shaped argon glow discharge created under 1 atm pressure. Such an atmospheric plasma brush requires extremely low power of less than 20 W to operate; and therefore is essentially a low-temperature discharge as confirmed by gas-phase temperature measurements. Two bacteria, Escherichia coli (E. coli) and Micrococcus luteus (M. luteus), seeded in various media were subjected to plasma treatment and their survivability was examined. It was found that such argon atmospheric plasma brush is very effective in destruction of the bacteria cells. With nutrient broth and standard methods agar as supporting media, a cell reduction in a level of 6 orders of magnitude was observed for E. coli within 3-4 min plasma treatment. A similar level of cell reduction was also observed for M. luteus in the two media with 2 or 3 min plasma treatment. The plasma treatment effects on the bacteria cell structures were also examined using scanning electron microscopy and the cell structure damages due to the plasma exposure were observed on both bacteria. The possible sterilization mechanism of the argon plasmas is also discussed in this article.


Assuntos
Argônio/química , Contaminação de Equipamentos/prevenção & controle , Escherichia coli/crescimento & desenvolvimento , Micrococcus luteus/crescimento & desenvolvimento , Esterilização , Escherichia coli/ultraestrutura , Infecções por Escherichia coli/prevenção & controle , Temperatura Alta , Viabilidade Microbiana , Micrococcus luteus/ultraestrutura , Microscopia Eletrônica de Varredura , Esterilização/instrumentação , Esterilização/métodos , Fatores de Tempo
6.
Can J Microbiol ; 51(2): 141-8, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16091772

RESUMO

Proteins with molecular masses of 36 and 34 kDa (Bti36 and Bti34) were isolated from entomocidal crystals formed by Bacillus thuringiensis ssp. israelensis cells. The samples of Bti36 contained the admixture of a protein with a molecular mass of 33 kDa (Bti33), apparently a product of proteolysis of Bti36. These 3 proteins are significantly different in N-terminal sequences from known delta-endotoxins of B. thuringiensis and show antibacterial activity toward Micrococcus luteus. The combination of Bti36 and Bti33 also suppresses the growth of some other microorganisms including Streptomyces chrysomallus. The effects of the mixture of Bti36 and Bti33 on the M. luteus cell surface and on the surface of S. chrysomallus cells and exospores are similar, but they are different from the effect of endotoxin Cry11A on micrococcal cells.


Assuntos
Antibacterianos/farmacologia , Bacillus thuringiensis/metabolismo , Proteínas de Bactérias/isolamento & purificação , Toxinas Bacterianas/química , Endotoxinas/química , Micrococcus luteus/efeitos dos fármacos , Streptomyces/efeitos dos fármacos , Aedes/efeitos dos fármacos , Animais , Antibacterianos/química , Bacillus thuringiensis/fisiologia , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/química , Proteínas de Bactérias/farmacologia , Proteínas Hemolisinas , Testes de Sensibilidade Microbiana , Micrococcus luteus/ultraestrutura , Microscopia Eletrônica de Varredura , Esporos Bacterianos/fisiologia , Esporos Bacterianos/ultraestrutura , Streptomyces/ultraestrutura
7.
Mikrobiologiia ; 73(4): 516-29, 2004.
Artigo em Russo | MEDLINE | ID: mdl-15521179

RESUMO

Using electron microscopy (ultrathin sections and freeze-fractures), we investigated the ultrastructure of the resting cells formed in the cultures of Micrococcus luteus, Arthrobacter globiformis, and Pseudomonas aurantiaca under conditions of prolonged incubation (up to 9 months). These resting cells included cyst-like forms that were characterized by complex cell structure and the following ultrastructural properties: (i) a thickened or multiprofiled cell wall (CW), typically made up of a layer of the preexisting CW and one to three de novo synthesized murein layers; (ii) a thick, structurally differentiated capsule; (iii) presence of large intramembrane particles (d = 180-270 A), occurring both on the PF and EF sides of the membrane fractures of M. luteus and A. globiformis; (iv) a peculiar structure of the cytoplasm, which was either fine-grained or lumpy (coarse-grained) in different parts of the cell population; and (v) a condensed nucleoid. Intense formation of cyst-like cells occurred in aged (2- to 9-month-old) bacterial cultures grown on diluted complex media or on nitrogen-, carbon-, and phosphorus-limited synthetic media, as well as in suspensions of cells incubated in media with sodium silicate. The general morphological properties, ultrastructural organization, and physiological features of cyst-like cells formed during the developmental cycle suggest that constitutive dormancy is characteristic of non-spore-forming bacteria.


Assuntos
Arthrobacter/ultraestrutura , Micrococcus luteus/ultraestrutura , Pseudomonas/ultraestrutura , Arthrobacter/crescimento & desenvolvimento , Carbono , Parede Celular/ultraestrutura , Microscopia Crioeletrônica , Meios de Cultura , Micrococcus luteus/crescimento & desenvolvimento , Nitrogênio , Peptidoglicano/ultraestrutura , Silicatos
8.
Mikrobiologiia ; 73(3): 406-15, 2004.
Artigo em Russo | MEDLINE | ID: mdl-15315236

RESUMO

The electron microscopic examination of the thin sections of cells of the yeasts Saccharomyces cerevisiae and Pichia pastoris and the gram-positive bacteria Micrococcus luteus and Bacillus subtilis showed that cell treatment with the chaotropic salts guanidine hydrochloride (6 M) and guanidine thiocyanate (4 M) at 37 degrees C for 3-5 h or at 100 degrees C for 5-6 min induced degradative processes, which affected almost all cellular structures. The cell wall, however, retained its ultrastructure, integrity, and rigidity, due to which the morphology of cells treated with the chaotropic salts did not change. High-molecular-weight DNA was localized in a new cell compartment, ectoplasm (a peripheral hydrophilic zone). The chaotropic salts destroyed the outer and inner membranes and partially degraded the outer and inner protein coats of Bacillus subtilis spores, leaving their cortex (the murein layer) unchanged. The spore core became accessible to stains and showed the presence of regions with high and low electron densities. The conditions of cell treatment with the chaotropic salts were chosen to provide for efficient in situ PCR analysis of the 16S and 18S rRNA genes with the use of oligonucleotide primers.


Assuntos
Bacillus subtilis/ultraestrutura , Desinfetantes/farmacologia , Guanidina/farmacologia , Guanidinas/farmacologia , Micrococcus luteus/ultraestrutura , Pichia/ultraestrutura , Saccharomyces cerevisiae/ultraestrutura , Tiocianatos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/fisiologia , Temperatura Alta , Micrococcus luteus/efeitos dos fármacos , Microscopia Eletrônica , Pichia/efeitos dos fármacos , Reação em Cadeia da Polimerase , Saccharomyces cerevisiae/efeitos dos fármacos , Esporos Bacterianos/ultraestrutura , Fatores de Tempo
9.
Microb Ecol ; 48(1): 120-7, 2004 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15164240

RESUMO

A growing body of evidence now supports the isolation of microorganisms from ancient materials. However, questions about the stringency of extraction methods and the genetic relatedness of isolated organisms to their closest living relatives continue to challenge the authenticity of these ancient life forms. Previous studies have successfully isolated a number of spore-forming bacteria from organic and inorganic deposits of considerable age whose survival is explained by their ability to enter suspended animation for extended periods of time. However, despite a number of putative reports, the isolation of non-spore-forming bacteria and an explanation for their survival have remained enigmatic. Here we describe the isolation of non-spore-forming cocci from a 120-million-year-old block of amber, which by genetic, morphological, and biochemical analyses are identified as belonging to the bacterial species Micrococcus luteus. Although comparison of 16S rRNA sequences from the ancient isolates with their modern counterparts is unable to confirm the precise age of these bacteria, we demonstrate, using complementary molecular and cell biological techniques, evidence supporting the view that these (and related modern members of the genus) have numerous adaptations for survival in extreme, nutrient-poor environments, traits that will assist in this bacteria's persistence and dispersal in the environment. The bacteria's ability to utilize succinic acid and process terpine-related compounds, both major components of natural amber, support its survival in this oligotrophic environment.


Assuntos
Fósseis , Micrococcus luteus/genética , Micrococcus luteus/metabolismo , Filogenia , Âmbar , Sequência de Bases , Análise por Conglomerados , Meios de Cultura , Evolução Molecular , Ácidos Graxos/metabolismo , Fluorescência , Israel , Éteres Metílicos/metabolismo , Micrococcus luteus/isolamento & purificação , Micrococcus luteus/ultraestrutura , Microscopia Eletrônica , Dados de Sequência Molecular , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
10.
Biochim Biophys Acta ; 1624(1-3): 125-30, 2003 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-14642822

RESUMO

Defensins are a major group of antimicrobial peptides and are found widely in vertebrates, invertebrates and plants. Invertebrate defensins have been identified from insects, scorpions, mussels and ticks. In this study, chemically synthesized tick defensin was used to further investigate the activity spectrum and mode of action of natural tick defensin. Synthetic tick defensin showed antibacterial activity against many Gram-positive bacteria but not Gram-negative bacteria and low hemolytic activity, characteristic of invertebrate defensins. Furthermore, bactericidal activity against pathogenic Gram-positive bacteria including Bacillus cereus, Enterococcus faecalis and methicillin-resistant Staphylococcus aureus was observed. However, more than 30 min was necessary for tick defensin to completely kill bacteria. The interaction of tick defensin with the bacterial cytoplasmic membrane and its ability to disrupt the membrane potential was analyzed. Tick defensin was able to disrupt the membrane potential over a period of 30-60 min consistent with its relatively slow killing. Transmission electron microscopy of Micrococcus luteus treated with tick defensin showed lysis of the cytoplasmic membrane and leakage of cellular cytoplasmic contents. These findings suggest that the primary mechanism of action of tick defensin is bacterial cytoplasmic membrane lysis. In addition, incomplete cell division with multiple cross-wall formation was occasionally seen in tick defensin-treated bacteria showing pleiotropic secondary effects of tick defensin.


Assuntos
Antibacterianos/farmacologia , Defensinas/farmacologia , Bactérias Gram-Positivas/efeitos dos fármacos , Carrapatos/imunologia , Sequência de Aminoácidos , Animais , Hemólise/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Micrococcus luteus/efeitos dos fármacos , Micrococcus luteus/ultraestrutura , Microscopia Eletrônica , Dados de Sequência Molecular
11.
Can J Microbiol ; 49(1): 37-44, 2003 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-12674346

RESUMO

Mosquitocidal endotoxins Cry4B, Cry11A, and CytA from Bacillus thuringiensis ssp. israelensis as well as the products of their limited proteolysis display antibacterial activity relative to Micrococcus luteus. The endotoxin Cry11A also induces the lysis of the micrococcus protoplasts. Potassium and sodium ions and N-acetylgalactosamine increased the antibacterial effect of Cry11A, whereas glucose and N-acetylglucosamine inhibited it. The endotoxin Cry11A displays the antibacterial effect on some other microorganisms.


Assuntos
Bacillus thuringiensis/química , Proteínas de Bactérias/farmacologia , Toxinas Bacterianas , Endotoxinas/farmacologia , Micrococcus luteus/efeitos dos fármacos , Micrococcus luteus/ultraestrutura , Bacillus thuringiensis/classificação , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/genética , Endotoxinas/genética , Glucose/farmacologia , Proteínas Hemolisinas , Micrococcus luteus/crescimento & desenvolvimento , Microscopia Eletrônica , Potássio/farmacologia , Protoplastos , Sódio/farmacologia
12.
J Med Chem ; 45(3): 663-9, 2002 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-11806717

RESUMO

The antibacterial activities of cationic steroid antibiotics and cationic peptide antibiotics have been compared. Depolarization of bacterial membranes, activation of bacterial stress-related gene promoters, and changes in bacterial morphologies caused by these antibiotics suggest that cationic steroid and peptide antibiotics share mechanistic aspects. Modified cationic steroid antibiotics display improved selectivity for prokaryotic cells over eukaryotic cells presumably due to increased charge recognition.


Assuntos
Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Esteroides/farmacologia , Proteínas de Xenopus , Sequência de Aminoácidos , Antibacterianos/síntese química , Antibacterianos/química , Peptídeos Catiônicos Antimicrobianos/química , Cátions , Membrana Celular/efeitos dos fármacos , Contagem de Colônia Microbiana , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Genes Bacterianos , Medições Luminescentes , Testes de Sensibilidade Microbiana , Micrococcus luteus/efeitos dos fármacos , Micrococcus luteus/ultraestrutura , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/crescimento & desenvolvimento , Espectrometria de Fluorescência , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Staphylococcus aureus/crescimento & desenvolvimento , Esteroides/síntese química , Esteroides/química , Streptococcus pyogenes/efeitos dos fármacos , Streptococcus pyogenes/crescimento & desenvolvimento
13.
Mikrobiologiia ; 70(6): 776-87, 2001.
Artigo em Russo | MEDLINE | ID: mdl-11785134

RESUMO

Under the influence of alkyl hydroxybenzene (C6-AHB) added to cell suspensions at a concentration of (1-5) x 10(-3) M, the cells of Saccharomyces cerevisiae, Micrococcus luteus, and Thioalkalivibrio versutus underwent dramatic changes in the ultrastructural organization of cell membranes, cytoplasm, and inclusions. In yeast suspension, the first changes were observed after 15 min in the structure of slit-like invaginations in the cytoplasmic membrane (CM): they were shortened and thickened. In the subsequent 30 to 60 min, CM ruptures were formed in the regions devoid of intramembrane protein particles and in the slit-like invaginations. After 24 h, complete disintegration of the intracellular membrane structures and conglomeration of the ribosomal part of the cytoplasm occurred. Similar changes were observed on the exposure of gram-positive and gram-negative bacteria to AHB. However, the cell wall in all the microorganisms studied was not destroyed, and in Micrococcus luteus it was even thickened. These mummified forms were preserved as morphologically intact but nonviable cells for more than three years of observations. By their ultrastructural characteristics, these mummified forms of microorganisms were similar to the fossilized microorganisms discovered by us in fibrous kerite. The concept of micromummies was formulated. AHB are supposed to play an important role in the process of fossilization of microorganisms in nature.


Assuntos
Ectothiorhodospira/ultraestrutura , Micrococcus luteus/ultraestrutura , Fenóis/farmacologia , Saccharomyces cerevisiae/ultraestrutura , Adaptação Fisiológica , Ectothiorhodospira/química , Técnica de Fratura por Congelamento , Secções Congeladas , Membranas Intracelulares/ultraestrutura , Micrococcus luteus/química , Fosfolipídeos/análise , Saccharomyces cerevisiae/química
14.
Folia Microbiol (Praha) ; 45(3): 259-62, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11271812

RESUMO

Two oil-degrading bacteria identified as Pseudomonas aeruginosa and Micrococcus luteus were isolated from crude-oil-polluted soils in Nigeria. The organisms were grown on n-hexadecane and sodium succinate and then examined for the presence of hydrocarbon inclusions. Inclusion bodies were found in n-hexadecane-grown cells and were absent in succinate-grown cells. Formation of hydrocarbon inclusion bodies appears to be a general phenomenon among hydrocarbon utilizers.


Assuntos
Micrococcus luteus/ultraestrutura , Petróleo/metabolismo , Pseudomonas aeruginosa/metabolismo , Pseudomonas aeruginosa/ultraestrutura , Microbiologia do Solo , Poluentes do Solo , Alcanos/metabolismo , Meios de Cultura , Corpos de Inclusão/ultraestrutura , Micrococcus luteus/isolamento & purificação , Micrococcus luteus/metabolismo , Pseudomonas aeruginosa/isolamento & purificação , Succinatos , Clima Tropical
15.
APMIS ; 107(7): 645-54, 1999 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10440060

RESUMO

Mixed bacterial communities are formed by unrelated bacteria on solid media. Mixed bacterial communities on solid media are similar to "classical" colonies and are formed after the growth of a large number of unrelated bacteria simultaneously plated onto a limited area of agar. The morphology of the mixed bacterial communities was similar for different combinations of bacteria and did not change when the bacteria were plated on different media. Different bacterial strains form zones of individual and mixed growth in the structure of mixed bacterial communities. The results of electron microscopic examination indicate that mixed bacterial communities are isolated from their external environment by a surface film. The basic part of this film is formed by an elementary membrane. The membrane of the surface film of mixed bacterial communities is a stable structure occupying a large surface area. The results of this investigation seem to indicate the existence of a special type of co-operation between different species of bacteria. This type of co-operation may be very important in the regulation of interactions between different bacteria and between bacteria and the environment.


Assuntos
Escherichia coli/ultraestrutura , Bactérias Gram-Positivas/ultraestrutura , Pseudomonas aeruginosa/ultraestrutura , Bacillus cereus/crescimento & desenvolvimento , Bacillus cereus/fisiologia , Bacillus cereus/ultraestrutura , Brevibacterium/crescimento & desenvolvimento , Brevibacterium/fisiologia , Brevibacterium/ultraestrutura , Enterococcus faecalis/crescimento & desenvolvimento , Enterococcus faecalis/fisiologia , Enterococcus faecalis/ultraestrutura , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/fisiologia , Bactérias Gram-Positivas/crescimento & desenvolvimento , Bactérias Gram-Positivas/fisiologia , Micrococcus luteus/crescimento & desenvolvimento , Micrococcus luteus/fisiologia , Micrococcus luteus/ultraestrutura , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pseudomonas aeruginosa/fisiologia , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/fisiologia , Staphylococcus aureus/ultraestrutura
16.
J Appl Microbiol ; 87(6): 856-66, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-10664909

RESUMO

Staphylococcin T (StT), an antibacterial agent produced by a Staphylococcus cohnii T strain, was purified to homogeneity by ammonium sulphate precipitation, gel filtration, cation exchange and fast performance liquid chromatography (FPLC). The final yield was about 20%, and over a 1000-fold increase in the specific activity was obtained. Mass determination (2166 Da), amino acid sequencing (Ile-Ala-Xaa-Lys-Phe-Leu-Xaa-Xaa-Pro-Gly-Xaa-Ala-Lys-block) and DNA sequencing demonstrated that StT is identical to gallidermin, a lanthionine-containing antimicrobial peptide. StT has a broad spectrum of bactericidal activity against Gram-positive and some Gram-negative bacteria. StT appears to damage cell membrane, and as a result causes an efflux of ions and an immediate block in macromolecular synthesis. Moreover, electron microscopic observations reveal morphological changes, with a loss of ribosomes and condensation of the nucleoid DNA. These changes are followed by a dissolution of the cell contents resulting in a bacterial ghost composed of seemingly intact cell walls with remnants of the cytoplasmic membrane and internal structure. Since StT exhibits antimicrobial activity especially against the Staphylococcus species, this compound may be of use in the treatment of staphylococcal infections.


Assuntos
Antibacterianos/isolamento & purificação , Peptídeos , Staphylococcus/química , Sequência de Aminoácidos , Antibacterianos/química , Antibacterianos/farmacologia , Bacteriocinas , Sequência de Bases , Cromatografia , Cromatografia Líquida de Alta Pressão , Calefação , Concentração de Íons de Hidrogênio , Focalização Isoelétrica , Espectrometria de Massas , Micrococcus luteus/efeitos dos fármacos , Micrococcus luteus/crescimento & desenvolvimento , Micrococcus luteus/ultraestrutura , Dados de Sequência Molecular
17.
Mikrobiologiia ; 65(6): 782-9, 1996.
Artigo em Russo | MEDLINE | ID: mdl-9102554

RESUMO

Under certain cultivation conditions, the bacteria Bacillus cereus and Micrococcus luteus form cystlike refractive cells (up to 60% of the total number) that retain viability over a long time, are metabolically inactive and thermotolerant and possess specific ultrastructure. These properties allow them to be attributed to a new type of resting forms of microorganisms.


Assuntos
Bacillus cereus/fisiologia , Fatores Biológicos/fisiologia , Micrococcus luteus/fisiologia , Aerobiose , Bacillus cereus/efeitos dos fármacos , Bacillus cereus/ultraestrutura , Meios de Cultura , Homeostase , Temperatura Alta , Micrococcus luteus/efeitos dos fármacos , Micrococcus luteus/ultraestrutura , Nitrogênio/farmacologia , Esporos Bacterianos
18.
FEBS Lett ; 384(2): 107-11, 1996 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-8612803

RESUMO

Recently, we have developed a photocrosslinking approach which uses anthracene as a photoactivatable group and which allows us to determine the lateral distribution of lipids in membranes quantitatively. In synchronous cultures of the gram-positive bacterium Micrococcus luteus, this approach shows that the spatial distribution of phosphatidylglycerol and dimannosyldiacylglycerol, the two major lipids in the bacterial membrane, varies greatly during the cell cycle. Minimum heterogeneity was observed during cell growth while maximum heterogeneity was detected during cell division.


Assuntos
Glicolipídeos/análise , Lipídeos de Membrana/análise , Micrococcus luteus/química , Fosfolipídeos/análise , Ciclo Celular , Cromatografia em Camada Fina , Micrococcus luteus/crescimento & desenvolvimento , Micrococcus luteus/ultraestrutura , Fosfatidilgliceróis/análise
19.
Antimicrob Agents Chemother ; 39(3): 714-9, 1995 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-7793878

RESUMO

Mersacidin is an antibiotic peptide produced by Bacillus sp. strain HIL Y-85,54728 that belongs to the group of lantibiotics. Its activity in vivo against methicillin-resistant Staphylococcus aureus strains compares with that of the glycopeptide antibiotic vancomycin (S. Chatterjee, D. K. Chatterjee, R. H. Jani, J. Blumbach, B. N. Ganguli, N. Klesel, M. Limbert, and G. Seibert, J. Antibiot. 45:839-845, 1992). Incubation of Staphylococcus simulans 22 with mersacidin resulted in the cessation of growth and slow lysis. Biosyntheses of DNA, RNA, and protein were not affected, whereas incorporation of glucose and D-alanine was inhibited and a regular reduction in the level of cell wall thickness was observed. Thus, unlike type A lantibiotics, mersacidin does not form pores in the cytoplasmic membrane but rather inhibits cell wall biosynthesis. Comparison with tunicamycin-treated cells indicated that peptidoglycan rather than teichoic acid metabolism is primarily affected. Mersacidin caused the excretion of a putative cell wall precursor into the culture supernatant. The formation of polymeric peptidoglycan was effectively inhibited in an in vitro assay, probably on the level of transglycosylation. In contrast to vancomycin, the activity of mersacidin was not antagonized by the tripeptide diacetyl-L-Lys-D-Ala-D-Ala, indicating that on the molecular level its mode of action differs from those of glycopeptide antibiotics. These data together with electron microscopy suggest that mersacidin acts on a novel target, which opens new perspectives for the treatment of methicillin-resistant S. aureus.


Assuntos
Antibacterianos/farmacologia , Bactérias/metabolismo , Peptídeos , Peptidoglicano/biossíntese , Sequência de Aminoácidos , Bactérias/efeitos dos fármacos , Bactérias/ultraestrutura , Bacteriocinas , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , Meios de Cultura , Escherichia coli/efeitos dos fármacos , Escherichia coli/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Micrococcus luteus/efeitos dos fármacos , Micrococcus luteus/metabolismo , Micrococcus luteus/ultraestrutura , Microscopia Eletrônica , Dados de Sequência Molecular , Fosfatos/metabolismo , Staphylococcus/efeitos dos fármacos , Staphylococcus/metabolismo , Staphylococcus/ultraestrutura , Vancomicina/farmacologia
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