Green methods have become vital for sustainable development of the scientific and commercial sphere; however, they can bring new challenges, including the need for detailed characterization and elucidation of efficacy of their products. In this study, green method of silver nanoparticles (AgNPs) production was employed using an extract from grapevine canes. The aim of the study was to contribute to the knowledge about biosynthesized AgNPs by focusing on elucidation of their antifungal efficiency based on their size and/or hypothesized synergy with bioactive substances from Vitis vinifera cane extract. The antifungal activity of AgNPs capped and stabilized with bioactive compounds was tested against the opportunistic pathogenic yeast Candida albicans. Two dispersions of nanoparticles with different morphology (characterized by SEM-in-STEM, DLS, UV-Vis, XRD, and AAS) were prepared by modification of reaction conditions suitable for economical production and their long-term stability monitored for six months was confirmed. The aims of the study included the comparison of the antifungal effect against suspension cells and biofilm of small monodisperse AgNPs with narrow size distribution and large polydisperse AgNPs. The hypothesis of synergistic interaction of biologically active molecules from V. vinifera extracts and AgNPs against both cell forms were tested. The interactions of all AgNPs dispersions with the cell surface and changes in cell morphology were imaged using SEM. All variants of AgNPs dispersions were found to be active against suspension and biofilm cells of C. albicans; nevertheless, surprisingly, larger polydisperse AgNPs were found to be more effective. Synergistic action of nanoparticles with biologically active extract compounds was proven for biofilm cells (MBIC80 20 mg/L of polydisperse AgNPs in extract), while isolated nanoparticles suspended in water were more active against suspension cells (MIC 20 mg/L of polydisperse AgNPs dispersed in water). Our results bring new insight into the economical production of AgNPs with defined characteristics, which were proven to target a specific mode of growth of significant pathogen C. albicans.
- MeSH
- antibakteriální látky farmakologie MeSH
- antifungální látky metabolismus farmakologie MeSH
- biofilmy MeSH
- Candida albicans metabolismus MeSH
- kovové nanočástice * MeSH
- mikrobiální testy citlivosti MeSH
- rostlinné extrakty metabolismus farmakologie MeSH
- stříbro * metabolismus farmakologie MeSH
- voda metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Rhamnolipids are extensively studied biosurfactants due to their potential in many industrial applications, eco-friendly production and properties. However, their availability for broader application is severely limited by their production costs, therefore the optimization of efficacy of their cultivation gains significance as well as the information regarding the physio-chemical properties of rhamnolipids resulting from various cultivation strategies. In this work, the bioprocess design focused on optimization of the rhamnolipid yield of Pseudomonas aeruginosa DBM 3774 utilizing the response surface methodology (RSM). Six carbon sources were investigated for their effect on the rhamnolipid production. The RSM prediction improved the total rhamnolipid yield from 2.2 to 13.5 g/L and the rhamnolipid productivity from 11.6 to 45.3 mg/L/h. A significant effect of the carbon source type, concentration and the C/N ratio on the composition of the rhamnolipid congeners has been demonstrated for cultivation of P. aeruginosa DBM 3774 in batch cultivation. Especially, changes in presence of saturated fatty acid in the rhamnolipid congeners, ranging from 18.8% of unsaturated fatty acids (carbon source glycerol; 40 g/L) to 0% (sodium citrate 20 g/L) were observed. This demonstrates possibilities of model based systems as basis in cultivation of industrially important compounds like biosurfactants rhamnolipids and the importance of detailed study of interconnection between cultivation conditions and rhamnolipid mixture composition and properties.
- Publikační typ
- časopisecké články MeSH
Resistance to adverse conditions is widespread in the microbial world. Microorganisms resistant to ionizing radiation form a technologically interesting but little-explored group. This work focuses on the mechanisms of resistance to radiation in representatives of the Actinobac-teria phylum, both in terms of detoxification mechanisms and in terms of repairing DNA damage.
The emergence of antibiotic resistance in opportunistic pathogens represents a huge problem, the solution for which may be a treatment with a combination of multiple antimicrobial agents. Sodium salt of cobalt bis-dicarbollide (COSAN.Na) is one of the very stable, low-toxic, amphiphilic boron-rich sandwich complex heteroboranes. This compound has a wide range of potential applications in the biological sciences due to its antitumor, anti-HIV-1, antimicrobial and antibiofilm activity. Our study confirmed the ability of COSAN.Na (in the concentration range 0.2-2.48 μg/mL) to enhance tetracycline, erythromycin, and vancomycin action towards Staphylococcus epidermidis planktonic growth with an additive or synergistic effect (e.g., the combination of 1.24 μg/mL COSAN.Na and 6.5 μg/mL TET). The effective inhibitory concentration of antibiotics was reduced up to tenfold most efficiently in the case of tetracycline (from 65 to 6.5 μg/mL). In addition, strong effect of COSAN.Na on disruption of the cell envelopes was determined using propidium iodide uptake measurement and further confirmed by transmission electron microscopy. The combination of amphiphilic COSAN.Na with antibiotics can therefore be considered a promising way to overcome antibiotic resistance in Gram-positive cocci.
- Publikační typ
- časopisecké články MeSH
Metody zelené syntézy nanočástic zaznamenávají v současnosti významný rozvoj, především díky velké efektivitě, ekonomickým a eko‐ logickým aspektům včetně šetrnosti těchto metod k životnímu prostředí. Tyto metody využívají pro přípravu nanočástic látky s organic‐ kým původem, které zajišťují redukující a stabilizující funkce pro přípravu disperze nanočástic spektra kovů. Zvláště výhodné je využití rostlinných odpadů pro zisk extraktů obsahujících celou řadu látek s redukční a biologickou aktivitou. V závislosti na druhu rostliny, ze kterého se získal extrakt lze rychle připravit stabilní nanočástice s různou velikostí, tvarem a z různých prvků. Takto získané nanočástice mají významný potenciál jak z hlediska srovnání jejich výroby s metodami fyzikálně‐chemickými, tak z hlediska srovnání jejich antimikro‐ biálních aktivit s tradičními desinfekčními činidly. Potenciál těchto metod spočívá v možnosti zapojení do principů cirkulární ekonomiky za snižování nákladů produkce, efektivnějšího využití odpadů a celkově příznivým ekonomickým i ekologickým aspektům.
The methods of green synthesis of nanoparticles are currently undergoing important development, mainly due to high efficiency, eco‐ nomic, ecological and environmentally friendly approach. Green methods use for the preparation of nanoparticles organic compounds, which provide reducing and stabilizing functions for the dispersion of metal nanoparticles. The use of plant waste materials is especially advantageous, as they contain a wide range of substances with reducing and biological activity. Different plant species and parts provide extracts for quick and reliable methods for preparation of stable dispersions with various sizes and shapes of nanoparticles. These na‐ noparticles have significant potential both their comparison with with physico‐chemical methods of production and in their antimicrobial activities. The potential of green biosynthesis methods lies in their contribution to the principles of circular economy for reducing produ‐ ction costs, efficient use of waste materials and overall favorable economic and ecological aspects.
Pseudomonas aeruginosa is a gram-negative bacterium capable of forming persistent biofilms that are extremely difficult to eradicate. The species is most infamously known due to complications in cystic fibrosis patients. The high mortality of cystic fibrosis is caused by P. aeruginosa biofilms occurring in pathologically overly mucous lungs, which are the major cause facilitating the organ failure. Due to Pseudomonas biofilm-associated infections, remarkably high doses of antibiotics must be administered, eventually contributing to the development of antibiotic resistance. Nowadays, multidrug resistant P. aeruginosa is one of the most terrible threats in medicine, and the search for novel antimicrobial drugs is of the utmost importance. We have studied the effect of low molecular weight chitosan (LMWCH) on various stages of P. aeruginosa ATCC 10145 biofilm formation and eradication, as well as on production of other virulence factors. LMWCH is a well-known naturally occurring agent with a vast antimicrobial spectrum, which has already found application in various fields of medicine and industry. LMWCH at a concentration of 40 mg/L was able to completely prevent biofilm formation. At a concentration of 60 mg/L, this agent was capable to eradicate already formed biofilm in most studied times of addition (2-12 h of cultivation). LMWCH (50 mg/L) was also able to suppress pyocyanin production when added 2 and 4 h after cultivation. The treatment resulted in reduced formation of cell clusters. LMWCH was proved to be an effective antibiofilm agent worth further clinical research with the potential to become a novel drug for the treatment of P. aeruginosa infections.
Pterostilbene (PTE) is a naturally occurring compound originally isolated from Pterocarpus spp. It has been widely used in traditional Indian medicine and later discovered to have various beneficial pharmacological effects such as antioxidant properties, hypoglycaemic or antitumor, and antimicrobial activity. This work is focused on demonstrating PTE synergistic effect with erythromycin and tetracycline to reduce their needed effective concentration for suppression of Staphylococcus epidermidis planktonic cells growth and biofilm formation. The secondary aim is to find these combinations effect on the production of its virulence factors. PTE was found to be effective in inhibition of its planktonic cells with MIC80 values 25-37.5 mg l-1. Simultaneously, it decreased the metabolic activity of biofilm cells and was especially effective on a clinical isolate (MBIC80 = 35 mg l-1) in contrast to the conventional antibiotics. In combination, PTE helped the antibiotics to overcome the tolerance of S. epidermidis biofilm cells (5 mg l-1 of each antibiotic with 49 mg l-1 PTE caused more than 85% inhibition of metabolic activity). It permeabilized cytoplasmic membrane of S. epidermidis cells and altered their surface hydrophobicity. Therefore, PTE has a great potential to enhance antibiotics action in the treatment of infections caused by this pathogen.
Vitis vinifera canes are waste material of grapevine pruning and thus represent cheap source of high-value polyphenols. In view of the fact that resistance of many pathogenic microorganisms to antibiotics is a growing problem, the antimicrobial activity of plant polyphenols is studied as one of the possible approaches. We have investigated the total phenolic content, composition, antioxidant activity, and antifungal activity against Candida biofilm of an extract from winter canes and a commercially available extract from blue grapes. Light microscopy and confocal microscopy imaging as well as crystal violet staining were used to quantify and visualize the biofilm. We found a decrease in cell adhesion to the surface depending on the concentration of resveratrol in the cane extract. The biofilm formation was observed as metabolic activity of Candida albicans, Candida parapsilosis and Candida krusei biofilm cells and the minimum biofilm inhibitory concentrations were determined. The highest inhibition of metabolic activity was observed in Candida albicans biofilm after treatment with the cane extract (30 mg/L) and blue grape extract (50 mg/L). The composition of cane extract was analyzed and found to be comparatively different from blue grape extract. In addition, the content of total phenolic groups in cane extract was three-times higher (12.75 gGA/L). The results showed that cane extract was more effective in preventing biofilm formation than blue grape extract and winter canes have proven to be a potential source of polyphenols for antimicrobial and antibiofilm treatment.
- Publikační typ
- časopisecké články MeSH
Background: Hopanoids modify plasma membrane properties in bacteria and are often compared to sterols that modulate membrane fluidity in eukaryotes. In some microorganisms, they can also allow adaptations to extreme environments. Methods: Hopanoids were identified by liquid chromatography-mass spectrometry in fourteen strains of thermophilic bacteria belonging to five genera, i.e., Alicyclobacillus, Brevibacillus, Geobacillus, Meiothermus, and Thermus. The bacteria were cultivated at temperatures from 42 to 70 °C. Results: Regardless of the source of origin, the strains have the same tendency to adapt the hopanoid content depending on the cultivation temperature. In the case of aminopentol, its content increases; aminotetrol does not show a significant change; and in the case of aminotriol the content decreases by almost a third. The content of bacteriohopanetetrol and bacteriohopanetetrol glycoside decreases with increasing temperature, while in the case of adenosylhopane the opposite trend was found. Conclusions: Changes in hopanoid content can be explained by increased biosynthesis, where adenosylhopane is the first intermediate in the biosynthesis of the hopanoid side chain.
- Publikační typ
- časopisecké články MeSH
This study evaluated the effect of low-molecular weight chitosan on Staphylococcus epidermidis, a common colonizer of joint implants and other prosthetic devices. We have also attempted to elucidate its mechanism of action. Chitosan was found to be effective against both the planktonic and biofilm cells (MIC80 35-40 mg/L; MBIC80 40-150 mg/L), in contrast to the antibiotics erythromycin and tetracycline with no antibiofilm activity (MBIC80 not found). In combination, chitosan had an additive effect with antibiotics on suspension growth of S. epidermidis (FICi 0.7-1.0), and the combinatory action caused a complete inhibition of biofilm metabolic activity in some cases. In addition, chitosan caused rapid cellular damage and enhanced antihaemolytic activity of tetracycline in combination towards S. epidermidis biofilm cells. Chitosan efficiently inhibited S. epidermidis growth acting via cell membrane damage, yet the extent of antimicrobial and antibiofilm activities was quite strain-specific. It was proved to be a very efficient antimicrobial agent worth further examination as a potent candidate in pharmaceutical research. Apart from antimicrobial activity, it also acted as antivirulence enhancing agent which is a very promising strategy for alternative infectious diseases treatment.
