CssRS is a two-component system that plays a pivotal role in mediating the secretion stress response in Bacillus subtilis. This system upregulates the synthesis of membrane-bound HtrA family proteases that cope with misfolded proteins that accumulate within the cell envelope as a result of overexpression or heat shock. Recent studies have shown the induction of CssRS-regulated genes in response to cell envelope stress. We investigated the induction of the CssRS-regulated htrA promoter in the presence of different cell wall- and membrane-active substances and observed induction of the CssRS-controlled genes by glycopeptides (vancomycin and teicoplanin), polymyxins B and E, certain β-lactams, and detergents. Teicoplanin was shown to elicit remarkably stronger induction than vancomycin and polymyxin B. Teicoplanin and polymyxin B induced the spxO gene expression in a CssRS-dependent fashion, resulting in increased activity of Spx, a master regulator of disulfide stress in Bacillus subtilis. The CssRS signaling pathway and Spx activity were demonstrated to be involved in Bacillus subtilis resistance to teicoplanin and polymyxin B.

• MeSH
• antibakteriální látky * farmakologie   MeSH
• Bacillus subtilis * genetika   účinky léků   metabolismus   MeSH
• bakteriální proteiny * genetika   metabolismus   MeSH
• polymyxin B * farmakologie   MeSH
• promotorové oblasti (genetika) MeSH
• regulace genové exprese u bakterií * účinky léků   MeSH
• signální transdukce MeSH
• teikoplanin * farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH

Biofilm formation is an effective survival strategy of plant-associated microorganisms in hostile environments, so the application of biofilm-forming and exopolysaccharide (EPS)-producing beneficial microbes to plants has received more attention in recent years. This study examined the ability of biofilm and EPS production of Bacillus subtilis and Bacillus thuringiensis strains under different NaCl concentrations (0, 50, 100, 200, and 400 mmol/L), pH values (5.5, 6.5, 7.5, and 8.5), and phosphate levels (0, 25, 50, and 100 mmol/L at 0 and 400 mmol/L NaCl). B. subtilis BS2 and B. thuringiensis BS6/BS7 strains significantly increased biofilm formation in a similar pattern to EPS production under salt stress. B. subtilis BS2/BS3 enhanced biofilm production at slightly acidic pH with a lower EPS production but the other strains formed considerably more amount of biofilm and EPS at alkaline pH. Interestingly, higher levels of phosphate substantially decreased biofilm and EPS production at 0 mmol/L NaCl but increased biofilm formation at 400 mmol/L salt concentration. Overall, contrary to phosphate, salt and pH differently influenced biofilm and EPS production by Bacillus strains. EPS production contributed to biofilm formation to some extent under all the conditions tested. Some Bacillus strains produced more abundant biofilm under salt and pH stress, indicating their potential to form in vivo biofilms in rhizosphere and on plants, particularly under unfavorable conditions.

• MeSH
• Bacillus subtilis fyziologie   metabolismus   účinky léků   MeSH
• Bacillus thuringiensis fyziologie   účinky léků   MeSH
• bakteriální polysacharidy * metabolismus   biosyntéza   MeSH
• biofilmy * účinky léků   růst a vývoj   MeSH
• chlorid sodný * farmakologie   metabolismus   MeSH
• fosfáty * metabolismus   farmakologie   MeSH
• koncentrace vodíkových iontů MeSH
• Publikační typ
• časopisecké články MeSH

Lipophosphonoxins (LPPOs) are small modular synthetic antibacterial compounds that target the cytoplasmic membrane. First-generation LPPOs (LPPO I) exhibit an antimicrobial activity against Gram-positive bacteria; however they do not exhibit any activity against Gram-negatives. Second-generation LPPOs (LPPO II) also exhibit broadened activity against Gram-negatives. We investigated the reasons behind this different susceptibility of bacteria to the two generations of LPPOs using model membranes and the living model bacteria Bacillus subtilis and Escherichia coli. We show that both generations of LPPOs form oligomeric conductive pores and permeabilize the bacterial membrane of sensitive cells. LPPO activity is not affected by the value of the target membrane potential, and thus they are also active against persister cells. The insensitivity of Gram-negative bacteria to LPPO I is probably caused by the barrier function of the outer membrane with LPS. LPPO I is almost incapable of overcoming the outer membrane in living cells, and the presence of LPS in liposomes substantially reduces their activity. Further, the antimicrobial activity of LPPO is also influenced by the phospholipid composition of the target membrane. A higher proportion of phospholipids with neutral charge such as phosphatidylethanolamine or phosphatidylcholine reduces the LPPO permeabilizing potential.

• MeSH
• antibakteriální látky chemická syntéza   farmakologie   MeSH
• Bacillus subtilis chemie   cytologie   účinky léků   MeSH
• Escherichia coli chemie   cytologie   účinky léků   MeSH
• fosfatidylcholiny analýza   metabolismus   MeSH
• fosfatidylethanolaminy analýza   metabolismus   MeSH
• kationické antimikrobiální peptidy chemická syntéza   farmakologie   MeSH
• lipidové dvojvrstvy MeSH
• membránové potenciály účinky léků   MeSH
• mikrobiální testy citlivosti MeSH
• permeabilita buněčné membrány MeSH
• vnější bakteriální membrána chemie   účinky léků   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Daptomycin is a calcium-dependent lipodepsipeptide antibiotic clinically used to treat serious infections caused by Gram-positive pathogens. Its precise mode of action is somewhat controversial; the biggest issue is daptomycin pore formation, which we directly investigated here. We first performed a screening experiment using propidium iodide (PI) entry to Bacillus subtilis cells and chose the optimum and therapeutically relevant conditions (10 µg/ml daptomycin and 1.25 mM CaCl2) for the subsequent analyses. Using conductance measurements on planar lipid bilayers, we show that daptomycin forms nonuniform oligomeric pores with conductance ranging from 120 pS to 14 nS. The smallest conductance unit is probably a dimer; however, tetramers and pentamers occur in the membrane most frequently. Moreover, daptomycin pore-forming activity is exponentially dependent on the applied membrane voltage. We further analyzed the membrane-permeabilizing activity in B. subtilis cells using fluorescence methods [PI and DiSC3(5)]. Daptomycin most rapidly permeabilizes cells with high initial membrane potential and dissipates it within a few minutes. Low initial membrane potential hinders daptomycin pore formation.

• MeSH
• antibakteriální látky farmakologie   MeSH
• Bacillus subtilis účinky léků   metabolismus   MeSH
• biologický transport fyziologie   MeSH
• cytotoxické proteiny tvořící póry farmakologie   MeSH
• daptomycin farmakologie   MeSH
• membránové potenciály účinky léků   MeSH
• mikrobiální testy citlivosti MeSH
• permeabilita buněčné membrány účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Spx is a Bacillus subtilis transcription factor that interacts with the alpha subunits of RNA polymerase. It can activate the thiol stress response regulon and interfere with the activation of many developmental processes. Here, we show that Spx is a central player orchestrating the heat shock response by up-regulating relevant stress response genes as revealed by comparative transcriptomic experiments. Moreover, these experiments revealed the potential of Spx to inhibit transcription of translation-related genes. By in vivo and in vitro experiments, we confirmed that Spx can inhibit transcription from rRNA. This inhibition depended mostly on UP elements and the alpha subunits of RNA polymerase. However, the concurrent up-regulation activity of stress genes by Spx, but not the inhibition of translation related genes, was essential for mediating stress response and antibiotic tolerance under the applied stress conditions. The observed inhibitory activity might be compensated in vivo by additional stress response processes interfering with translation. Nevertheless, the impact of Spx on limiting translation becomes apparent under conditions with high cellular Spx levels. Interestingly, we observed a subpopulation of stationary phase cells that contains raised Spx levels, which may contribute to growth inhibition and a persister-like behaviour of this subpopulation during outgrowth.

• MeSH
• Bacillus subtilis účinky léků   enzymologie   účinky záření   MeSH
• fyziologický stres * MeSH
• genetická transkripce MeSH
• oxidační stres * MeSH
• proteosyntéza MeSH
• reakce na tepelný šok * MeSH
• regulace genové exprese u bakterií * MeSH
• stanovení celkové genové exprese MeSH
• transkripční faktory metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Avian eggs contend with omnipresent microorganisms entering the egg interior, where they affect embryo viability and hatchling phenotype. The incubation behaviour and deposition of egg white antimicrobial proteins (AMPs) vary highly across the avian altricial-precocial spectrum. Experimental evidence of how these alterations in avian reproductive strategies affect the antimicrobial properties of the precocial and altricial egg interior is lacking, however. Here, we tested the egg white antimicrobial activity in eggs of two representative model species, from each end of the avian altricial-precocial spectrum, against potentially pathogenic and beneficial probiotic microorganisms. Eggs were experimentally treated to mimic un-incubated eggs in the nest, partial incubation during the egg-laying period, the onset of full incubation and the increased deposition of two main egg white AMPs, lysozyme and ovotransferrin. We moreover assessed to what extent egg antimicrobial components, egg white pH and AMP concentrations varied as a result of different incubation patterns. Fully incubated precocial and altricial eggs decreased their antimicrobial activity against a potentially pathogenic microorganism, whereas partial incubation significantly enhanced the persistence of a beneficial probiotic microorganism in precocial eggs. These effects were most probably conditioned by temperature-dependent alterations in egg white pH and AMP concentrations. While lysozyme concentration and pH decreased in fully incubated precocial but not altricial eggs, egg white ovotransferrin increased along with the intensity of incubation in both precocial and altricial eggs. This study is the first to experimentally demonstrate that different incubation patterns may have selective antimicrobial potential mediated by species-specific effects on antimicrobial components in the egg white.

• MeSH
• antiinfekční látky farmakologie   MeSH
• Bacillus subtilis účinky léků   MeSH
• Columbidae fyziologie   MeSH
• Coturnix fyziologie   MeSH
• Micrococcus luteus účinky léků   MeSH
• muramidasa farmakologie   MeSH
• ovotransferin farmakologie   MeSH
• ovum enzymologie   fyziologie   MeSH
• ptačí proteiny farmakologie   MeSH
• rozmnožování * MeSH
• vaječný bílek chemie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Muscotoxins are cyanobacterial cyclic lipopeptides with potential applications in biomedicine and biotechnology. In this study, Desmonostoc muscorum CCALA125 strain extracts were enriched by polymeric resin treatment, and subjected to HPCCC affording three cyclic lipopeptides (1⁻3), which were further repurified by semi-preparative HPLC, affording 1, 2, and 3, with a purity of 86%, 92%, and 90%, respectively. The chemical identities of 2⁻3 were determined as muscotoxins A and B, respectively, by comparison with previously reported ESI-HRMS/MS data, whereas 1 was determined as a novel muscotoxin variant (muscotoxin C) using NMR and ESI-HRMS/MS data. Owing to the high yield (50 mg), compound 2 was broadly screened for its antimicrobial potential exhibiting a strong antifungal activity against Alternaria alternata, Monographella cucumerina, and Aspergillus fumigatus, with minimum inhibitory concentration (MIC) values of 0.58, 2.34, and 2.34 µg/mL; respectively, and weak antibacterial activity against Bacillus subtilis with a MIC value of 37.5 µg/mL. Compounds 1 and 3 were tested only against the plant pathogenic fungus Sclerotinia sclerotiorum due to their low yield, displaying a moderate antifungal activity. The developed chromatographic method proved to be an efficient tool for obtaining muscotoxins with potent antifungal properties.

• MeSH
• antiinfekční látky chemie   izolace a purifikace   farmakologie   MeSH
• Ascomycota účinky léků   MeSH
• Bacillus subtilis účinky léků   MeSH
• bakteriální toxiny chemie   izolace a purifikace   farmakologie   MeSH
• cyklické peptidy chemie   farmakologie   MeSH
• lipopeptidy chemie   farmakologie   MeSH
• mikrobiální testy citlivosti MeSH
• molekulární struktura MeSH
• sinice metabolismus   MeSH
• syntetické pryskyřice chemie   MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Publikační typ
• časopisecké články MeSH

Diamond nanoparticles (DNPs) of various types have been recently reported to possess antibacterial properties. Studies have shown a decrease of the colony forming ability on agar plates of the bacteria that had been previously co-incubated with DNPs in the suspension. Before plating, bacteria with DNPs were adequately diluted in order to obtain a suitable number of colony forming units. However, residual DNPs were still present on an agar plate, concentrated on the surface during the plating process; this introduces a potential artifact which might affect colony growth. The effect of DNPs remaining on the surface, alongside growing bacteria, has not been previously investigated. In this work, we present the experiments designed to investigate the effect of DNPs on bacterial survival and on the growth of the bacterial colony on a solid media. We employed Escherichia coli and Bacillus subtilis as models of Gram-negative and Gram-positive bacteria, respectively, and Proteus mirabilis as a model of bacterium exhibiting swarming motility on the surfaces. We analyzed the number, area, and weight of bacterial colonies grown on the agar surface covered with DNPs. We did not observe any bactericidal effect of such applied DNPs. However, in all bacterial species used in this work, we observed the appreciable reduction of colony area, which suggests that DNPs obstruct either bacterial growth or motility. The most obvious effect on colony growth was observed in the case of motile P. mirabilis. We show that DNPs act as the mechanical barrier blocking the lateral colony growth.

• MeSH
• antibakteriální látky chemie   farmakologie   MeSH
• Bacillus subtilis účinky léků   růst a vývoj   MeSH
• Bacteria cytologie   účinky léků   růst a vývoj   MeSH
• diamant chemie   farmakologie   MeSH
• Escherichia coli účinky léků   růst a vývoj   MeSH
• mikrobiální testy citlivosti MeSH
• nanočástice chemie   MeSH
• povrchové vlastnosti MeSH
• Proteus mirabilis účinky léků   růst a vývoj   MeSH
• velikost částic MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Publikační typ
• časopisecké články MeSH

The antimicrobial effect of OKCEL® H-D, a topical, absorbable hemostatic textile prepared from oxidized cellulose, was tested. Testing by dilution and diffusion methods was conducted on a spectrum of 27 select microorganisms, including also antibiotic-resistant strains. OKCEL® H-D showed inhibitory effects on nearly all tested bacteria. In testing using the dilution suspension method, the majority of bacteria showed decrease in cell density by 7-8 orders of magnitude after just 6 h of exposure. For clinical isolates of antibiotic-resistant strains, a reduction occurred after 24 h of exposure. In testing the antimicrobial effects of OKCEL® H-D by the dilution method was least effective on spore-forming Bacillus subtilis, for which no antimicrobial effect was detected after 48 h, and on Mycobacterium smegmatis, for which the number of cells decreased by four orders of magnitude only after 24 h. By the diffusion method, inhibition zones were recorded for nearly all test microorganisms except for Staphylococcus aureus, M. smegmatis, and Listeria monocytogenes. No growth beneath the tested OKCEL® H-D material was recorded, however, even for the latter-named bacteria strains, which attests to its good inhibitory effect.

• MeSH
• antibakteriální látky chemie   farmakologie   MeSH
• Bacillus subtilis účinky léků   růst a vývoj   MeSH
• bakteriální léková rezistence MeSH
• celulosa oxidovaná chemie   farmakologie   MeSH
• Listeria monocytogenes účinky léků   růst a vývoj   MeSH
• mikrobiální testy citlivosti MeSH
• Staphylococcus aureus účinky léků   růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH

Surfactin, an anionic lipopeptide produced by Bacillus subtilis, is an antimicrobial that targets the cytoplasmic membrane. Nowadays it appears increasingly apparent that the mechanism of resistance against these types of antibiotics consists of target site modification. This prompted us to investigate whether the surfactin non-producing strain B. subtilis 168 changes its membrane composition in response to a sublethal surfactin concentration. Here we show that the exposure of B. subtilis to surfactin at concentrations of 350 and 650 μg/ml (designated as SF350 and SF650, respectively) leads to a concentration-dependent growth arrest followed by regrowth with an altered growth rate. Analysis of the membrane lipid composition revealed modifications both in the polar head group and the fatty acid region. The presence of either surfactin concentration resulted in a reduction in the content of the major membrane phospholipid phosphatidylglycerol (PG) and increase in phosphatidylethanolamine (PE), which was accompanied by elevated levels of phosphatidic acid (PA) in SF350 cultures. The fatty acid analysis of SF350 cells showed a marked increase in non-branched high-melting fatty acids, which lowered the fluidity of the membrane interior measured as the steady-state fluorescence anisotropy of DPH. The liposome leakage of carboxyfluorescein-loaded vesicles resembling the phospholipid composition of surfactin-adapted cells showed that the susceptibility to surfactin-induced leakage is strongly reduced when the PG/PE ratio decreases and/or PA is included in the target bilayer. We concluded that the modifications of the phospholipid content of B. subtilis cells might provide a self-tolerance of the membrane active surfactin.

• MeSH
• Bacillus subtilis chemie   účinky léků   růst a vývoj   MeSH
• cyklické peptidy farmakologie   MeSH
• fluidita membrány účinky léků   MeSH
• fosfolipidy analýza   MeSH
• lipopeptidy farmakologie   MeSH
• mastné kyseliny analýza   MeSH
• membránové lipidy analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH