Mezilidské vztahy v rodinách dívek s mentální anorexií

Katedra psychologieFilozofická fakult

Silver Nanoparticle Production Mediated by Vitis vinifera Cane Extract: Characterization and Antibacterial Activity Evaluation

The ever-growing range of possible applications of nanoparticles requires their mass production. However, there are problems resulting from the prevalent methods of nanoparticle production; physico-chemical routes of nanoparticle synthesis are not very environmentally friendly nor cost-effective. Due to this, the scientific community started exploring new methods of nanoparticle assembly with the aid of biological agents. In this study, ethanolic Vitis vinifera cane extract combined with silver nitrate was used to produce silver nanoparticles. These were subsequently characterized using UV-visible (UV-Vis) spectrometry, transmission electron microscopy, and dynamic light-scattering analysis. The antimicrobial activity of produced nanoparticles was tested against the planktonic cells of five strains of Gram-negative bacterium Pseudomonas aeruginosa (PAO1, ATCC 10145, ATCC 15442, DBM 3081, and DBM 3777). After that, bactericidal activity was assessed using solid medium cultivation. In the end, nanoparticles’ inhibitory effect on adhering cells was analyzed by measuring changes in metabolic activity (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay-MTT). Our results confirmed that ethanolic Vitis vinifera cane extract is capable of mediating silver nanoparticle production; synthesis was conducted using 10% of extract and 1 mM of silver nitrate. The silver nanoparticles’ Z-average was 68.2 d nm, and their zeta potential was –30.4 mV. These silver nanoparticles effectively inhibited planktonic cells of all P. aeruginosa strains in concentrations less than 5% v/v and inhibited biofilm formation in concentrations less than 6% v/v. Moreover, minimum bactericidal concentration was observed to be in the range of 10–16% v/v. According to the results in this study, the use of wine agriculture waste is an ecological and economical method for the production of silver nanoparticles exhibiting significant antimicrobial properties

Influence of Humic Acids on the Growth of the Microorganisms Utilizing Toxic Compounds (Comparison between Yeast and Bacteria)

Humic acids, a heterogenic group of natural organic macromolecules with a complex polymeric structure, form a significant part of the soil and water environment. They have a high surface activity, thus they are able to interact with other components in the environment (mineral and microbial cell surfaces, organic and inorganic compounds). This work is focused on humic acid effects on the growth of microorganisms utilizing phenolic compounds as the sole carbon and energy source. For this purpose a bacterial population Rhodococcus erythropolis and a yeast strain Candida maltosa were used. Both microorganisms had been adapted to the degradation of phenol and phenolic compounds for many years. However, a toxic effect of these compounds still occurs. The addition of humic acids into the cultivation medium extended toleration of the bacteria to higher concentrations of phenolic compounds and increased the growth of this microbial population as well. In the case of the yeast, humic acids inhibited the growth. Humic acids easily form an additive layer on the surface of the investigated microorganisms. The generated humic acid layer can probably serve as a transport barrier and thus influence the growth of microbial populations