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Biomedical subjects

V Jirků

Publications and source records attributed to V Jirků.

17 recordsLinked to original sources
PubMed2006

Mild hydrolysis of nitriles by Fusarium solani strain O1.

High levels of an aromatic nitrilase (about 37 microkat/L culture) were induced in Fusarium solani O1 after transfer of the mycelium from a rich medium into a medium with 20 mmol/L picolinonitrile. The mycelium was entrapped in lense-shaped particles consisting of a polyvinyl alcohol/polyethylene glycol copolymer (LentiKats). The cell-free extract was immobilized by hydrophobic binding onto a Butyl Sepharose column. The enzyme was useful for the mild hydrolysis of nicotinonitrile, isonicotinonitrile and benzonitrile.

Aminohydrolases↗
PubMed2005

Colonization of surfaces by phenolic compounds utilizing microorganisms.

The aim of the present study is to determine optimal adhesive interaction of phenolic compounds utilizing Candida maltosa and Rhodococcus erythropolis when adhering to kaolin, silicone, synthetic foil (Steriking R40) and fluorinated silicones, comparing cell and support surface hydrophobicity. In parallel, the interfering effect of detergents was investigated. Data obtained show that the less hydrophobic supports display high initial cell adhesion when contacted with the cell type with a lower surface hydrophobicity (yeast cell) but most stable yeast biofilms are those formed on highly hydrophobic fluorinated silicones. On the other hand, support hydrophobicity has no effect on bacterial cell detachment; however, bacterial biofilms are denser when growing on more hydrophobic supports. Both detergents interfere (independently on the cell type) with the early and late phases of biofilm development.

Bacterial Adhesion↗
PubMed2003

Host-vector system for phenol-degrading Rhodococcus erythropolis based on Corynebacterium plasmids.

The strain Rhodococcus erythropolis CCM2595, which was shown to degrade phenol, was chosen for genetic studies. To facilitate strain improvement using the methods of gene manipulation, the technique of genetic transfer was introduced and cloning vectors were constructed. Using the plasmid pFAJ2574, an electrotransformation procedure yielding up to 7x10(4) transformants/microg DNA was optimized. Escherichia coli- R. erythropolis shuttle vectors were constructed using the replicons pSR1 and pGA1 from Corynebacterium glutamicum. The small vector pSRK21 (5.8 kb) provides six unique cloning sites and selection of recombinant clones using alpha-complementation of beta-galactosidase in E. coli. This vector, exhibiting high segregational stability under non-selective conditions in R. erythropolis CCM2595, was applied to cloning and efficient expression of the gene coding for green fluorescent protein (gfpuv).

Base Sequence↗
PubMed2003

Comparison of yeast (Candida maltosa) and bacterial (Rhodococcus erythropolis) phenol hydroxylase activity and its properties in the phenolic compounds biodegradation.

Aromatic contaminants of the environment, to which belongs phenol and its derivatives, are toxic and in most of the cases hard to degrade. Removal of these pollutants by biological, gentle and effective way, depends on specific environmental conditions in the locality and on the biodegradation potential of the used microbial population. Closer characterization of the biodegradation and enzyme mechanisms is therefore an essential assumption of the successful implementation of microbes. This paper is focused on comparison of the biodegradation activity between the soil yeast Candida maltosa and bacteria Rhodococcus erythropolis towards various aromatics connected with determination of the first enzyme of the phenol biodegradation pathway: phenol hydroxylase (PH). The effect of substrate type, substrate concentration, growth phase of the microorganisms and presence of humic acids in the cultivation medium, on phenol biodegradation and PH activity are discussed.

Air Pollutants↗
PubMed1997

Changes in the starvation response through covalent cell attachment.

Covalent attachment of Candida utilis cells, possibly simulating natural microbial immobilizations, stimulated stable and significant enhancement of extracellular production of alkaline protease, specifically induced by four different starvation conditions. The enzyme analysis confirmed the identity of the proteases released under all conditions of starvation and no parallel production of other proteolytic enzyme. The enhancement phenomenon as a uniform and stable effect of the whole cell immobilization is discussed in relation to the effect of multipoint, cell-solid surface contact, potentially bringing positive modulations of complex, cellular functions.

Candida↗
PubMed1995

Covalent immobilization as a stimulus of cell wall composition changes.

Covalent immobilization of yeast cells by an activated diamine spacer is accompanied by increased levels of cell wall proteins, lipids, amino sugars, amino acids and acid phosphatase leakage, and by altered composition of mannoproteins. The observed changes in cell wall composition are attributed to the effect of cell-solid surface contact.

Cell Membrane↗
PubMed1983

Immobilized cells.

Three basic types of immobilization (i.e. without carrier, entrapment and immobilization on the carrier surface) of microbial cells, nonmicrobial cell populations and subcellular organelles are reviewed. These are further developed into a number of combined and less frequently used techniques of immobilization and application of cell biocatalysts for industrial biotransformation in pharmacy, food industry and agriculture, including novel approached and some unpublished authors' results.

Autolysis↗
PubMed1980

The extracellular system of beta-1,3-glucanases of Alternaria tenuissima and Aspergillus vesicolor.

During cultivation in a minimal medium with glucose Alternaria tenuissima and Aspergillus vesicolor produce constitutively alpha- and beta-glucanases. Fractions of beta-1,3-glucanases exhibiting affinity for laminarin were separated by means of gel filtration chromatography. Two neutral beta-1,3-glucanases with affinity for yeast glucan were isolated by affinity chromatography and further characterized.

Alternaria↗
PubMed1978

Changes in the lipid content during cell division of Saccharomyces cerevisiae.

Changes in the concentration of lipids were followed in synchronously dividing cells of Saccharomyces cerevisiae. Cell division was found to induce a pronounced increase in the concentration of sterols and changes in the concentrations of other types of lipids. The changes associated with the division process are only transient.

Cell Division↗