National Repository of Grey Literature 4 records found  Search took 0.00 seconds. 
Sequencing of DNA variable fragment coding aspartyl-tRNA synthetase suitable for taxonomic classification and phylogenetic analysis of bacterial genera closely related to genus Lactobacillales \n
Killer, Jiří ; Mrázek, Jakub
There was designed and tested a reliable marker for aspartyl-tRNA synthetase suitable for taxonomic classification and phylogenetic analysis of bacterial genera closely related to genus Lactobacillales. Method enables reliable a sensitive estimation in dairy starters and is independent on the phage cultivation. It is quick, reliable a sensitive estimation of dairy bacteria. It is possible to use it for basic research as well as for the effective analysis in dairy production plants. \n
New cryoprotectives in preservation of potentially probiotic bacteria of Bifidobacterium genus using freeze-drying procedure
Vrabcová, Petra ; Killer, Jiří (advisor) ; Jakub, Jakub (referee)
The probiotic bacteria of the genus Bifidobacterium are especially used in the dairy and pharmaceutical industry. They are present in the form of viable cells in pro(syn)biotic fermented milk, dried and freeze-dried products for its positive effects on the health. Lyophilization represents one of the widely used methods for long-term preservation of bifidobacteria. The lyophilization process is challenging, but very needed, and for this reason it is still necessary to explore new cryo(lyo)protective substances, which protect the microbial cultures more effectively before the negative effects of cryopreservation and lyophilization. The aim of the thesis was to test the various mixtures of substances containing specific oligosaccharides, which have prebiotic properties, from the point of view of their potential cryo(lyo)protective effect of lyophilization process. For the purposes of the study, twelve bifidobacterial strains of human and animal origin were selected. As a potential cryo(lyo)protectives were used solutions on the basis of 5x concentrated TPY medium with addition of FOS, 10% fructooligosaccharides (FOS) and the solution on the basis of porcine gastric mucin. Number of viable cells was determined in lyophilisates enriched by the concrete solutions in the time intervals (30 days, 3 months and 6 months) after lyophilization and compared with the control lyophilized samples (fresh cultures without the additive solutions). The potential cryo(lyo)protective effectiveness of 5x concentrated TPY medium solution has been demonstrated only in B. boum, B. breve, B. longum subsp. infantis a Bombiscardovia coagulans, where decreased the number of viable cells about four orders of magnitude. The potential cryo(lyo)protective effectiveness in 10% FOS solution was found only in B. thermacidophilum subsp. porcinum and Bombiscardovia coagulans, where was found half the number of viable cells. The highest potential cryo(lyo)protective effectiveness was observed for a solution on the basis of porcine gastric mucin. The highest number of viable cells was demonstrated in B. animalis subsp. lactis, B. boum, B. longum subsp. infantis, B. longum subsp. longum, B. pseudolongum subsp. globosum and B. thermacidophilum subsp. porcinum lyophilisates using this potential cryo(lyo)protective solution.
Microbial contamination of fruit teas
Kuřáková, Hana ; Popelářová, Eva (advisor) ; Killer, Jiří (referee)
Teas are consumed daily by millions of people on the World, therefor it is important to care for their microbial harmlessness. The aim of this work was to conduct a reaserch in regards to general information about fruit teas, their manufacturing and possibilities of contamination by undesirable microorganisms. In this research were also described important bacteria and fungii and we focused on mycotoxins and the elimination of microorganisms from a food. Representation of microorganisms in teabags was evaluated in practical part of this research. We focused on total quantity of microorganisms, coliform bacteria, that can be pathogenic in higher representation and micromycetes. Genus structure of micromycetes was important in particular, because they can produce metabolites, mycotoxins, that can be a cause for many diseases. Analyses were conducted by two methods. Variant classified as A was consisting of transformation of the teabag contents into the physiological solution. Variant classified as B was consisting of watering of the teabag contents. During evaluation, both of these variants were compared. From the results of this work it was found out, that quantities of microorganisms were relativem small. It was discovered, that during the sample preparation by watering the sample with boiling water (variant B) the quantity of microorganisms will lower, in some cases they were not present at all. The presence of wider genera of micromycetes was also discovered. Three genera were dominant Aspergillus, Penicillum and Cladosporium. These free found of genera can be dangerous, because of mycotoxins, however micromytes in variant B were only represented by genera Cladosporium and Penicillum and in small measure.
CHARAKTERIZACE NOVÝCH DRUHŮ LAKTOBACILŮ A JINÝCH BAKTERIÍ MLÉČNÉHO KVAŠENÍ Z TRÁVICÍHO TRAKTU SAVCŮ A HMYZU
Killer, Jiří ; Kopečný, Jan ; Mrázek, Jakub ; Koppová, Ingrid ; Rada, V. ; Kott, T.
Do skupiny probiotik, která jsou zjednodušeně definována jako „potravní doplňky obsahující přesně definované ţivé mikroorganismy mající prokazatelně pozitivní vliv na zdraví hostitele a zlepšující navíc vyuţívání ţivin“, náleţí především kmeny bifidobakterií, laktobacilů a jiných bakterií mléčného kvašení (druhy r. Lactococcus, Enterococcus, Streptococcus), ale také nepatogenní druhy bacilů (např. Bacillus coagulans), dále nepatogenní Escherichia coli, Propionibacterium freudenreichii a eukaryota v podobě některých druhů kvasinek (Saccharomyces boulardi). Zdá se, ţe výzkum probiotik je v současné době zaměřen na jiţ známé druhy především laktobacilů a bifidobakterií. Vzrůstá tedy význam testování probiotických vlastností jiných druhů bifidobakterií a bakterií mléčného kvašení (dále BMK), stejně tak izolace dosud nepopsaných druhů potenciálně vyuţitelných nejen v humánní medicíně, ale také v chovech hospodářských zvířat a v chovech hospodářsky významného hmyzu (včel a čmeláků).

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