共查询到20条相似文献,搜索用时 31 毫秒
1.
Navdeep Gholia Vandana Toky Sanjay Chhibber 《World journal of microbiology & biotechnology》2004,20(8):775-779
The effect of sub-inhibitory and inhibitory concentrations of antimicrobials including aminoglycosides, third generation cephalosporins and quinolones on the surface properties and adhesion of Klebsiella pneumoniae to uroepithelial cells (UECs) was examined. Antibiotics, ceftazidime and ofloxacin at 1/4, 1/8 × MIC and minimum inhibitory concentration (MIC) induced filament formation in bacteria, however cells treated with amikacin were similar in length to control organisms but showed a rough topology under the scanning electron microscope. An increase in bacterial hydrophobicity and decrease in uronic acid content were noted in the presence of ceftazidime and ofloxacin at MIC and sub-MIC level. However, amikacin at MIC level caused decreased hydrophobicity of the cells and the uronic content remained the same. This study clearly indicates that, although ceftazidime and ofloxacin brought about profound changes in cell surface characteristics, these changes did not result in any advantage to the bacterial cell in terms of adhesion. In contrast, with amikacin, which did not show any appreciable change in cell morphology or surface topology, exposure markedly increased the adherence of bacteria to UECs, indicating that the prophylactic use of this antibiotic not only induces resistance in bacteria but can also promote the colonization of UECs. 相似文献
2.
Nuno Cerca Silvia Martins Sanna Sillankorva Kimberly K. Jefferson Gerald B. Pier Rosario Oliveira Joana Azeredo 《Applied microbiology》2005,71(12):8677-8682
Low concentrations of antibiotics can inhibit microbial adherence to medical device surfaces. However, little is known about the changes that occur in the physiology of bacteria within biofilms formed in the presence of subinhibitory (sub-MIC) concentrations of antibiotics. In this study, the densities and matrix compositions ofbiofilms formed by two coagulase-negative Staphylococcus species in the absence and in the presence of sub-MIC concentrations of dicloxacillin were evaluated. Biofilms formed in the presence of sub-MIC concentrations of dicloxacillin contained less biomass, and there were notable changes in the composition of the biofilm matrix. Changes in the spatial structure were also verified by confocal scanning laser microscopy, indicating that biofilms grown in the presence of sub-MIC concentrations of dicloxicilln had a lower cell density. Physiological alterations in the bacteria within biofilms grown in the presence of subinhibitory concentrations of the antibiotic were also evaluated. The results showed that there were differences in bacterial surface characteristics when cultures were grown in the presence of sub-MIC concentrations of dicloxacillin, including decreased hydrophobicity and decreased expression of the exopolysaccharide poly-N-acetylglucosamine. The elemental composition of the cell surface was also analyzed, and whereas in Staphylococcus epidermidis there were decreases in the oxygen and nitrogen contents, in Staphylococcus haemolyticus there were increases in these two parameters. Additionally, increases in resistance to several antibiotics were observed for the cells within biofilms formed in the presence of dicloxacillin. 相似文献
3.
Cerca N Martins S Sillankorva S Jefferson KK Pier GB Oliveira R Azeredo J 《Applied and environmental microbiology》2005,71(12):8677-8682
Low concentrations of antibiotics can inhibit microbial adherence to medical device surfaces. However, little is known about the changes that occur in the physiology of bacteria within biofilms formed in the presence of subinhibitory (sub-MIC) concentrations of antibiotics. In this study, the densities and matrix compositions of biofilms formed by two coagulase-negative Staphylococcus species in the absence and in the presence of sub-MIC concentrations of dicloxacillin were evaluated. Biofilms formed in the presence of sub-MIC concentrations of dicloxacillin contained less biomass, and there were notable changes in the composition of the biofilm matrix. Changes in the spatial structure were also verified by confocal scanning laser microscopy, indicating that biofilms grown in the presence of sub-MIC concentrations of dicloxicilln had a lower cell density. Physiological alterations in the bacteria within biofilms grown in the presence of subinhibitory concentrations of the antibiotic were also evaluated. The results showed that there were differences in bacterial surface characteristics when cultures were grown in the presence of sub-MIC concentrations of dicloxacillin, including decreased hydrophobicity and decreased expression of the exopolysaccharide poly-N-acetylglucosamine. The elemental composition of the cell surface was also analyzed, and whereas in Staphylococcus epidermidis there were decreases in the oxygen and nitrogen contents, in Staphylococcus haemolyticus there were increases in these two parameters. Additionally, increases in resistance to several antibiotics were observed for the cells within biofilms formed in the presence of dicloxacillin. 相似文献
4.
Hualin Yang Yuanfeng Cai Meng Xia Xingyu Wang Limei Shi Pengfu Li Fanxiang Kong 《International Review of Hydrobiology》2011,96(2):141-148
Colony formation is highly import ant for the competitive advantage of the cyanobacterium Microcystis over other phytoplankton species. The laboratory‐grown colonial Microcystis strains isolated from Lake Taihu (China) maintained colonial forms under the low light condition (10 μE m–2 s–1). The cell surface hydrophobicities of the Microcystis colonies were measured by cyanobacterial adherence to xylene in comparison with unicellular Microcystis strains. The cells of the tested colonial strains were all hydrophobic, while the cells of the tested unicellular strains were all hydrophilic. Incubation under the higher light condition (75 μE m–2 s–1) leaded to the significant decrease in the cell hydrophobicities of the colonial Microcystis and the transition from colonial forms to unicellular forms. These findings indicated that the cell hydrophobicity of Microcystis may play a role in cell‐cell adherence and colony formation. Phosphate‐limitation, nitrate‐limitation and pH did not affect cell hydrophobicities of colonial Microcystis. Treatment with proteolytic enzymes had no effect on the cell hydrophobicity, indicating that cell surface proteins did not contribute to high cell hydrophobicity. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
Abstract The effect of 2, 4-dinitrophenol (DNP) on the extracelluar polysaccharides (EPS), cell surface charge, and the hydrophobicity of six marine bacterial cultures was studied, and its influence on attachment of these bacteria to glass and polystyrene was evaluated. DNP treatment did not influence cell surface charge and EPS production, but had a significant effect on hydrophobicity of both hydrophilic (p = 0.05) and hydrophobic (p = 0.01) cultures. Significant reduction in the attachment of all the six cultures to glass (p = 0.02) and polystyrene (p = 0.03) was observed after DNP treatment. Moreover, hydrophobicity but not the cell surface charge or EPS production influenced bacterial cell attachment to glass and polystyrene. From this study, it was evident that DNP treatment influenced bacterial cell surface hydrophobicity, which in turn, reduced bacterial adhesion to surfaces. 相似文献
6.
Effect of sub-MIC antibiotics on the cell surface and extracellular virulence determinants of Pseudomonas cepacia 总被引:1,自引:0,他引:1
D. McKenney L. Willcock P.A. Trueman D.G. Allison 《Journal of applied microbiology》1994,76(2):190-195
The effects of sub-MICs of ciprofloxacin and tobramycin on the cell surface characteristics and extracellular virulence factors of Pseudomonas cepacia were evaluated. Cells were grown in batch culture under iron-deficient and iron-replete conditions. At sub-MIC levels that did not affect bacterial growth cell surface hydrophobicity decreased under both iron-replete and iron-depleted conditions with ciprofloxacin, but increased with tobramycin under iron-sufficient conditions. Exopolysaccharide synthesis, lipase production and siderophore production were all significantly increased by the presence of ciprofloxacin under both growth conditions. Outer membrane protein and lipopolysaccharide profiles were not affected by exposure to the two antibiotics. 相似文献
7.
Surface hydrophobicity of hemagglutinatingVibrio cholerae, Vibrio parahaemolyticus, and NAG vibrios has been investigated. Most strains caused mannose-sensitive hemagglutination of monkey, guinea pig, chicken, and mannose-resistant hemagglutination of human erythrocytes with different degrees of hemagglutinating activity. Hemagglutinating strains adsorbed to a hydrophobic gel (Octyl Sepharose), whereas nonhemagglutinating strains failed to adsorb.Vibrio cholerae and other vibrios investigated seem to have pronounced surface hydrophobicity as estimated by Octyl Sepharose and they correspondingly autoaggregated into visible cell clumps in ammonium sulfate solution at low molarity (0.2–0.4 M). Nonhemagglutinating strains did not aggregate even at high (2 M) ammonium sulfate concentration. The presence of surface hemagglutinins of vibrios is growth-media-dependent. Strains, grown in four different liquid media, produced hemagglutinins and expressed pronounced surface hydrophobicity. Studies with electron microscopy revealed the presence of fimbriae on the vibrio cells. The number of fimbriae on the cells varied from strain to strain. Some strains possessed more than 300 fimbriae/cell whereas others had less than 10 fimbriae/cell. Vibrio hemagglutinins are easily detached from the cell surface by heating or sonication, and their cell surface hydrophobicity decreased simultaneously. 相似文献
8.
Zeng G Liu Z Zhong H Li J Yuan X Fu H Ding Y Wang J Zhou M 《Applied microbiology and biotechnology》2011,90(3):1155-1161
The effect of monorhamnolipid (monoRL) on the degradation of n-hexadecane by Candida tropicalis was investigated in this study. The concentration of hexadecane, cell growth, cell surface hydrophobicity (CSH), cell surface
zeta potential (CSZP), and FT-IR spectra of cellular envelope were tested to determine the mechanisms. MonoRL at the initial
concentrations of 11.4, 19, and 38 mg/l improved the degradation of hexadecane, and 19 mg/l was the best concentration. However,
114 mg/l monoRL suppressed the biodegradation probably because of the reduced bioavailability of hexadecane caused by the
micelles. The presence of monoRL changed the cell surface properties, which was demonstrated by the increased CSH, the increased
CSZP, and the changed FT-IR spectra of cellular envelope at 680 and 620 cm−1. The changes of cell surface properties may be a reason for the enhanced biodegradation of hexadecane by the yeast. The results
indicate the potential application of monoRL in the bioremediation of hydrocarbons. 相似文献
9.
Li-Qun Wang Xiang-Chen Meng Bai-Rong Zhang Yan Wang Yu-Lin Shang 《World journal of microbiology & biotechnology》2010,26(11):1999-2007
Adhesion ability of bifidobacteria to the intestinal mucosa is considered to be the prerequisite for colonization of bifidobacteria
and can protect against gastrointestinal pathogens infection. The aim of this study was to investigate bifidobacterial surface
traits related to adhesion ability in vitro and characterize the cell surface substances that may be involved in the adhesion
process of bifidobacteria. Twelve strains of Bifidobacterium spp. were studied for the correlation among their adhesion ability, autoaggregation ability and surface hydrophobicity. The
strain that exhibited good adhesion ability also showed high degree of hydrophobicity and strong autoaggregation ability.
Pepsin treatment had negative effect on the surface traits and adhesion ability of B. bifidum KLDS2.0603 (P < 0.01), it revealed that hydrophobicity, autoaggregation and adhesion process maybe mediated by proteinaceous components
on the surface of cell. Moreover, the adhesion and autoaggregation ability decreased after extraction of B. bifidum KLDS2.0603 with 5 mol l−1 LiCl, and an unreported 50-kDa surface protein which can bind to Caco-2 cell was observed by western blotting. Our results
indicated that surface hydrophobicity and autoaggregation ability can be used together for preliminary screening the strains
with high adhesion ability, and the present of the surface proteinaceous components would contribute to understand the interactions
between bifidobacteria and human intestinal mucosa. 相似文献
10.
A phenanthrene-utilizing bacterium was anaerobically isolated and identified as Rhodopseudomonas palustris. It tolerated up to 100 mg phenanthrene l−1 and degraded 50% of 50 mg phenanthrene l−1 over 10 days. The presence of phenanthrene caused a prolonged lag phase (2–3 days) in cell growth and affected the photopigments
biosynthesis, while DMSO (the solvent for phenanthrene) had no impact on cell growth. The cell surface hydrophobicity of the
isolate was also increased. 相似文献
11.
Rossana de Aguiar Cordeiro Rosana Serpa Patrícia Bruna Leite Mendes Antonio José de Jesus Evangelista Ana Raquel Colares Andrade Jônatas da Silva Franco 《Biofouling》2017,33(8):640-650
This study evaluated the effect of the protease inhibitor ritonavir (RIT) on Trichosporon asahii and Trichosporon inkin. Susceptibility to RIT was assessed by the broth microdilution assay and the effect of RIT on protease activity was evaluated using azoalbumin as substrate. RIT was tested for its anti-biofilm properties and RIT-treated biofilms were assessed regarding protease activity, ultrastructure and matrix composition. In addition, antifungal susceptibility, surface hydrophobicity and biofilm formation were evaluated after pre-incubation of planktonic cells with RIT for 15 days. RIT (200 μg ml?1) inhibited Trichosporon growth. RIT (100 μg ml?1) also reduced protease activity of planktonic and biofilm cells, decreased cell adhesion and biofilm formation, and altered the structure of the biofilm and the protein composition of the biofilm matrix. Pre-incubation with RIT (100 μg ml?1) increased the susceptibility to amphotericin B, and reduced surface hydrophobicity and cell adhesion. These results highlight the importance of proteases as promising therapeutic targets and reinforce the antifungal potential of protease inhibitors. 相似文献
12.
Well-defined laboratory strains as well as 72 clinical strains ofStaphylococcus aureus isolated from bovine mastitis were investigated for surface hydrophobicity by the salt aggregation test (SAT).Staphylococcus aureus strain Cowan 1, rich in protein A and fibronectin-binding surface proteins, was found to show high surface hydrophobicity, whereas strain Wood 46, deficient in these surface proteins, showed low surface hydrophobicity. SAT showed a significant difference in surface hydrophobicity (P<0.001) between protein A-positive and A-negative strains measured by 2-test analysis. Comparison of SAT values with results obtained from hydrophobic interaction chromatography (HIC) showed a good correlation (P<0.025). A high-level protein-A-producing mutant (SA 113prA-3) showed increased surface hydrophobicity as compared with the parent strain (SA 113), whereas ten protein-A-negative mutants showed low surface hydrophobicity in SAT. Of the 72 clinical isolates tested by SAT, 47 (65%) showed autoaggregating properties, i.e., the strains aggregated even in isotonic buffers. Tween 80 (1% vol/vol) and ethylene glycol (50% vol/vol) prevented autoaggregation of some hydrophobic strains aggregating in phosphate-buffered saline. However, 2M of a chaotropic agent (NaSCN) was more efficient in preventing autoaggregation of the strains tested. Heating of cell suspensions to 80°C or 100°C as well as trypsin andStreptomyces griseus protease treatment generally caused a decrease in the cell surface hydrophobicity. This indicates that protein A, fibronectin-binding proteins, and probably other as yet unidentified proteins contribute to the high surface hydrophobicity of most strains isolated from bovine mastitis. 相似文献
13.
Ł. Chrzanowski E. Kaczorek A. Olszanowski 《World journal of microbiology & biotechnology》2005,21(6-7):1273-1277
Summary The growth of Candida maltosa on hydrocarbons (dodecane and hexadecane) was influenced by adding various natural and synthetic surfactants. Microbial adhesion
to the hydrocarbon was used to measure the surface cell hydrophobicity of the yeast, which in the presence of a synthetic
surfactant correlated with the degree of hydrocarbon biodegradation. Non-ionic surfactants caused the highest degree of hydrocarbon
biodegradation corresponding the lowest hydrophobicity. A different correlation was observed with natural surfactants, of
which saponin was the most effective for hydrocarbon biodegradation, though the concentration of this surfactant had no influence
on surface cell hydrophobicity. 相似文献
14.
Hostacká A 《Microbios》2001,106(Z2):97-104
The effects of subinhibitory concentrations (sub-MIC) of ampicillin/sulbactam (AMP/sulbactam), on the surface hydrophobicity and the lipase activity of ten Acinetobacter strains, were examined. The alterations in the activities studied were strain and drug concentration dependent. Most of the strains treated showed a decrease in surface hydrophobicity to a different extent. The hydrophobic character of three strains exposed to 1/4 or 1/8 of the MIC of the antibiotic was changed to a hydrophilic state. The majority of Acinetobacter strains after treatment with antibiotic possessed increased lipolytic activity. AMP/sulbactam even at sub-MIC may interfere with possible virulence factors of Acinetobacter strains in vitro. 相似文献
15.
WilliamF. Fett StanleyF. Osman MichaelF. Dunn NickolasJ. Panopoulos 《Journal of Phytopathology》1992,135(2):135-152
The cell surface hydrophobicity and charge as well as surface polysaccharides of eight independent prototrophic hrp::-Tn5 mutants (Lindgren et al., J. Bacteriol. 168 , 512–522, 1986) were compared to the wild-type parent strain NPS3121 of Pseudomonas syringae pv. phaseolicola. No significant differences were found in cell surface charge, but mutant strain NPS4005 exhibited significantly lower cell surface hydrophobicity than the wild-type and the other mutant strains. The mutant strains all retained the ability to produce the exopolysaccharides (EPS) levan, a neutral fructan, and alginate, an acidic polymer. Relative amounts of EPS produced in vitro was dependent on culture conditions. Lipopolysaccharide (LPS) chemotypes were similar for all nine strains. Chemical as well as 13C-NMR analyses of the O-antigens from four wild-type strains of P. s. pv. phaseolicola representing two physiological races as well as the O-antigens of two strains of P. s. pv. syringae which belong to the same serogroup as P. s. pv. phaseolicola indicated that all of the O-antigens were very similar if not identical. LPS of three strains of P. s. pv. phaseolicola produced in vitro or in planta were also compared and no significant differences were detected. The altered phenotype of the Tn5 mutants of P. s. pv. phaseolicola does not appear to be due to changes in the ability to produce exopolysaccharides or to an altered composition of cell surface polysaccharides (LPS and EPS). However, a change in an unidentified cell surface component(s) leading to lowered cell surface hydrophobicity of mutant strain NPS4005 may be important. 相似文献
16.
Xinyue Ye Jian Wang Pengfei Xu Xiaoqian Yang Qixue Shi Genyan Liu Zhaoshi Bai Changlin Zhou Lingman Ma 《Microbial biotechnology》2023,16(9):1755-1773
Polymyxin resistance is conferred by MCR-1 (mobile colistin resistance 1)-induced lipopolysaccharide (LPS) modification of G− bacteria. However, the peptide MSI-1 exerts potent antimicrobial activity against mcr-1-carrying bacteria. To further investigate the potential role of MCR-1 in improving bacterial virulence and facilitating immune evasion, and the immunomodulatory effect of peptide MSI-1, we first explored outer membrane vesicle (OMV) alterations of mcr-1-carrying bacteria in the presence and absence of sub-MIC MSI-1, and host immune activation during bacterial infection and OMV stimulation. Our results demonstrated that LPS remodelling induced by MCR-1 negatively affected OMV formation and protein cargo by E. coli. In addition, MCR-1 diminished LPS-stimulated pyroptosis but facilitated mitochondrial dysfunction, further aggravating apoptosis in macrophages induced by OMVs of E. coli. Similarly, TLR4-mediated NF-κB activation was markedly alleviated once LPS was modified by MCR-1. However, peptide MSI-1 at the sub-MIC level inhibited the expression of MCR-1, further partly rescuing OMV alteration and attenuation of immune responses in the presence of MCR-1 during both infection and OMV stimulation, which can be exploited for anti-infective therapy. 相似文献
17.
Production of extracellular polymeric substances from Rhodopseudomonas acidophila in the presence of toxic substances 总被引:2,自引:0,他引:2
A hydrogen-producing photosynthetic bacteria strain, Rhodopseudomonas acidophila, was used to investigate the production of extracellular polymeric substances (EPS) in the presence of toxic substances and the effect of toxicants on bacterial surface characteristics. Addition of the toxic substances including Cu(II), Cr(VI), Cd(II) and 2,4-dichlorophenol (2,4-DCP) stimulated the production of EPS but reduced the cell dry weight. At concentrations of 30 mg l−1 Cu(II), 40 mg l−1 Cr(VI), 5 mg l−1 Cd(II) and 100 mg l−1 2,4-DCP, the EPS content increased by 5.5, 2.5, 4.0 and 1.4 times, respectively, than the control. These toxic substances also greatly influenced the proteins/carbohydrates ratio of EPS. The ratios in the presence of toxic substances were always higher than that of control. Furthermore, under toxic conditions, the increase in the protein content far exceeded than that of others in EPS, suggesting that extracellular proteins could protect cells against toxic substances. The toxic substances significantly changed the surface characteristics and flocculation ability of R. acidophila, such as surface energy, relative hydrophobicity and free energy of adhesion. 相似文献
18.
19.
M A Pereira M M Alves J Azeredo M Mota R Oliveira 《Journal of industrial microbiology & biotechnology》2000,24(3):181-186
The ability for biomass colonization of four porous mineral microcarriers (sepiolite, clay, pozzolana and foam glass-Poraver),
was studied and related to their surface properties. The surface hydrophobicity of the mineral carriers was a more important
factor influencing colonization by the anaerobic consortium than was surface charge. It was possible to correlate linearly
the degree of hydrophobicity with the biomass retention capacity. Although the thermodynamic theory did not explain adhesion,
an increase in cell attachment was directly related to the decrease of the positive values of the free energy of adhesion.
Surface roughness, porosity and the amount of surface Mg2+, were also determinant factors in bacterial immobilization. However a great biomass accumulation can originate a decrease
in biological activity due to mass transfer limitations. Journal of Industrial Microbiology & Biotechnology (2000) 24, 181–186.
Received 09 August 1999/ Accepted in revised form 01 December 1999 相似文献
20.
A. Pijanowska E. Kaczorek Ł. Chrzanowski A. Olszanowski 《World journal of microbiology & biotechnology》2007,23(5):677-682
Biodegradation and hydrophobicity of Pseudomonas spp. and Bacillus spp. strains were tested at different concentrations of the biosurfactant Quillaya saponin. A model mixture of hydrocarbon
(dodecane and hexadecane) was used for estimating the influence of surfactants on biodegradation. The bacterial adhesion to
hydrocarbon method for determination of bacterial cell surface hydrophobicity was exploited. Among the tested bacterial strains
the higher hydrophobicity was noticed for Pseudomonas aeruginosa TK. The hydrophobicity of this strain was 84%. The highest hydrocarbon biodegradation was observed for P. aeruginosa TK (49%) and Bacillus subtilis (35%) strains after 7 days of experiments. Generally the addition of Quillaya saponin increased hydrocarbon biodegradation
remarkably. The optimal concentration proved to be 80 mg l−1. The degree of hydrocarbon biodegradation was 75% for P. aeruginosa TK after the addition of saponin. However the most significant increase in biodegradation after addition of Quillaya saponin
was in the case of P. aeruginosa 25 and Pseudomonas putida (the increase of biodegradation from 21 to 52% and from 31 to 66%, respectively). It is worth mentioning that decrease of
hydrophobicity is correlated with the best biodegradation by P. aeruginosa strain. For the remaining strains, no significant hydrophobicity changes in relation to the system without surfactant were
noticed. 相似文献