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Probiotic lactic acid bacteria in food products
Sásková, Denisa ; Rittich, Bohuslav (referee) ; Španová, Alena (advisor)
In food industry molecular genetic methods based on DNA analysis are used for identification of probiotic microorganisms. An example of these methods is the polymerase chain reaction, in which specific fragments of DNA are amplified using short oligonucleotide primers. The teoretical part of this bachelor thesis follows probiotic bacteria, their features, beneficial health effects and use in food and clinical applications. The experimental part of the thesis focuses on an analysis of two probiotic dietary supplements. DNA was isolated from these products by method of phenol extraction. The use of PCR confirmed the presence of DNA of probiotic bacteria of genera Lactobacillus and Bifidobacterium.
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Study of aerobic cultivation conditions with select strain of Lactobacillus
Šupinová, Petra ; Burdychová, Radka (referee) ; Babák, Libor (advisor)
The aim of this study was focused on the study of conditions of growth of strains Lbc. paracasei subsp. paracasei CCDM 211, Lbc. paracasei CCDM 212, Lbc. paracasei subsp. paracasei CCDM 213 and Lbc. salivarius CCDM 216 in media with different amount of carbon-source (glucose, lactose and whey). Next part of the experiment was dealed with study of conditions of bacteria growth at stress conditions (lower pH). The purity od bacterial culture was verified with help of streaking. Purity DNA isolated from bacteria was tested using agarose gel electrophoresis, DNA concentration was estimated spectrophotometricaly. The presence of bacteria of genus Lactobacillus was proved using polymerase chain reaction (PCR) with genus specific primers.
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Identification of lactic acid bacteria in food products using amplification methods
Jurečková, Nela ; Trachtová, Štěpánka (referee) ; Španová, Alena (advisor)
The aim of the study was isolation of genomic DNA from 7 milk products (yogurts/ yogurt milk) in quality for use it in PCR. Magnetic microparticles (P(HEMA-co¬-GMA)) were used for the DNA isolation. DNA was reversibly adsorbed to the microspheres in the presence of 8% poly(ethylene glycol) PEG 6000 and 5 M sodium chloride. The adsorbed DNA was released from the microspheres in a low ionic strength TE buffer and use as DNA matrix in genus specific PCR Lactobacillus. The presence of DNA of genus Lactobacillus was detected in all analysed products.
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Identification of selected species of lactic acid bacteria in dairy products
Vystavělová, Růžena ; Trachtová, Štěpánka (referee) ; Rittich, Bohuslav (advisor)
Lactic acid bacteria are natural part of the human gastrointestinal tract. They are often used in food supplements and for the production of fermented dairy products. This thesis focuses on the identification of selected species of lactic acid bacteria and bifidobacteria in cheese and dairy products. Bacterial DNA was isolated by magnetic particles P(HEMA-co-GMA) from crude cell lysates from 9 products. Isolated DNA was amplified in genus-specific and species-specific polymerase chain reactions (PCR). The obtained amplicons were detected by agarose gel electrophoresis. The results of PCR were compared with those provided by the manufacturers and there has been declared a match.
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Study of yogurt composition in process of its preparation
Fajtl, Zbyněk ; Vítová, Eva (referee) ; Veselá, Mária (advisor)
This thesis deals with the study of yogurt preparation and changes during its storage. The theoretical part contains information about parameters affecting both the preparation and properties of the final product. The experimental part describes methods and procedures used for determination of critical parameters such as lactic acid, lactose, glucose and galactose concentrations (HPLC-RI), amounts of streptococci and lactobacilli. The data was graphically evaluated and commented on. The work also included sensory analysis in which the prepared yogurt was compared with commercially available products. The results of this work can serve both consumers and smaller yogurt producers.
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Technologie výroby a hodnocení jakostních parametrů bílých sýrů v solném nálevu
Mištová, Dominika
This thesis deals with the production technology and quality parameters evaluation of white brined cheeses. The characteristics, origins, technological procedures of production, and differences between them are described. The work aimed to carry out sensory evaluation and determination of physicochemical parameters. These criteria were identified for selected representatives of white brined cheeses available on the Czech market and for own samples produced under semi-operating conditions. A sub-objective was to compare both individual samples with each other and commercially available samples with the data given on the manufacturer's packaging. When comparing the results of the analysis with the data indicated on the package, the protein and fat content in both cases of commercially available samples was higher than declared by the manufacturer. On the other hand, the course of souring in the produced cheeses was insufficient. The titration results of the produced cheese samples differed by almost half from the cheeses purchased on the domestic market.
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Hodnocení mikrobiologických rizik jedlého hmyzu
Hedvičáková, Adéla
Eating edible insects is an activity that has recently become increasingly important. In order to use edible insects safely, it is necessary to carry out, among other things, an assessment of the risks associated with consumption. This work focused on the microbiological risk assessment of edible insects. The theoretical part of the thesis provides information on the nutritional properties of edible insects and the risks associated with insect consumption. It also mentions legislation related to the inclusion of insects in food. The thesis describes the impact of insects and their consumption on the environment and presents factors that need to be further addressed in the future. The thesis provides a list of important pathogenic microorganisms. In the practical part it is possible to find a statistical evaluation of the measured values of the pathogens present in the insects and in the feed. Total counts of microorganisms, Escherichia coli, Enterobacteriaceae, moulds, Staphylococcus aureus and lactic acid bacteria were determined. The results were compared with those of studies on similar topics.
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Active preparatives based on koji fermentation and medical mushrooms extracts
Živná, Kristýna ; Dzurická, Lucia (referee) ; Hoová, Julie (advisor)
This bachelor's thesis deals with the optimization of the growth of the rare species fungus of the hedgehog mushroom on cereal substrates for the purpose of the subsequent to cultivation of lactic acid bacteria. The theoretical part is focused on the description of the rare fungus species and the use of the cereals as substrate and the characterization of their active substances. It also deals with lactic fermentation and its use. In the experimental part, the preparation of the cereal substrate for the cultivation of the hedgehog mushroom was optimized. The method of inoculation of the cereals substrate with liquid mycelium in combination with plate mycelium was chosen as the most applicable. In this combination, the substrate does not dry out and grows evenly from both sides of the substrate. The composition of the cereal substrate with grown mycelium was characterized (antioxidant activity, carbohydrates, proteins). Finally, the substrate was inoculated with lactic bacteria. The lactic bacteria added nutritional value to the product. Fermentation products (antioxidant activity, carbohydrates, proteins) were characterized, and bacterial viability was analysed.
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Production and application of antimicrobial substances produced by lactic acid bacteria
Utíkalová, Kristýna ; Dzurická, Lucia (referee) ; Márová, Ivana (advisor)
The bachelor’s thesis deals with the production of antimicrobial substances by selected lactic acid bacteria of the genera Lactobacillus, Pediococcus and Bifidobacterium, in which the production of bacteriocins was assumed based on the conducted research. Bacteriocins are peptide-based antimicrobial substances with the potential to be widely used primarily as biopreservatives in the food industry. The theoretical part of the bachelor’s thesis focuses on antimicrobial substances produced by probiotic bacteria with a further concentration on bacteriocins produced by selected bacterial species and their current research and application in the industry. In the experimental part, the antimicrobial activity of prepared isolates from probiotic bacteria was tested on selected gram-negative and gram-positive bacteria. Specifically, this was done by the agar diffusion method, the broth dilution method and the cell viability test using resazurin. The amount of lactic acid and acetic acid in the individual isolates was determined using high performance reverse-phase liquid chromatography, which made it possible to further discuss their influence on the antimicrobial activity of the isolates. Strong antimicrobial activity against indicator bacteria was found in all isolates. For some isolates, it was higher than the antimicrobial activity of lactic acid itself together with its concentration which is found in the isolate according to the measurements. That is a significant stimulus for further research of these probiotic isolates, especially the L. acidophilus and L. plantarum isolates. For example, it was found that the tested isolate from L. acidophilus showed an inhibitory activity against S. epidermidis of 90,76 % and 81,62 % against E. coli at a concentration of 20,47 mg/ml. The isolate from L. acidophilus was subsequently applied to plant packaging with the potential of usage in the food industry, and the inhibitory activity of this isolate against contaminating microorganisms was observed.
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Production and characterization of antimicrobial substances from lactic acid bacteria
Franeková, Eliška ; Smetana, Jan (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on the production of antimicrobial compounds using lactic acid bacteria, their characterization and testing of their antimicrobial activity. The theoretical part of this work deals with the characteristics of lactic acid bacteria and the bacteriocins they produce, the possibilities of bacteriocin production and the factors that influence it. In the experimental part of this work, lactic acid bacteria Lactococcus lactis subsp. lactis, Lactobacillus helveticus and Bifidobacterium bifidum were cultivated, their growth curves and total protein content in supernatants after cultivation were measured. Cell-free culture supernatants were prepared by lyophilization and their antimicrobial activity against gram-positive and gram-negative bacteria was determined. The antimicrobial activity of commercial antimicrobial peptide nisin and a commercial preservative obtained using lactic acid bacteria was also measured. The sample obtained from Bifidobacterium bifidum was selected as the most effective of the isolates. Its antimicrobial activity was further tested on polymeric sausage packaging materials. Antimicrobial substances produced by lactic acid bacteria can be used in the food industry as preservatives or as a part of antimicrobial packaging, and in the pharmaceutical industry in materials for antimicrobial wound dressings.
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