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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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Hodnocení půdní organické hmoty ve vzorcích půd s odlišným managementem porostu
KOBLIC, Štěpán
The quality and quantity of soil organic matter and total organic carbon content are essential factors that significantly influence soil properties. This work focuses on evaluating soil organic matter in soil samples with different vegetation management. Concepts that are important for understanding the given topic are described in the literature review. The practical part deals with the application of mycoparasitic and entomopathogenic fungi and lactic acid bacteria to seeds and leaves (variants O1-O9) and the regular collection of soil samples on experimental plots in Zvíkov near České Budějovice. The collected samples were analyzed in the laboratory and statistically evaluated in terms of the phase of soil sampling (before sowing, during vegetation and at harvest) and management variants. The results showed that the treatment of common pea and white lupine with entomopathogenic fungi and lactic acid bacteria in ecologically managed farms affected the carbon management index, the carbon lability index, the carbon enrichment ratio, the rate of oxidation of labile organic matter and consequently, the organic matter reserves in the soil.
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Processing of sauerkraut juice to enhance its stability and consumer acceptance
Kohoutová, Lenka ; Mikulíková, Renata (referee) ; Hoová, Julie (advisor)
This diploma thesis focuses on the development possibilities of fruit and vegetable juices containing sauerkraut juice, the characterization of their nutritional and sensory qualities and their stability, as well as the potential for enriching selected juices with probiotic culture of Lactobacillus plantarum. The best combinations of various juice mixtures were selected based on sensory analysis and were stored for 30 days at 8 °C. Changes in selected parameters were monitored during the storage. Antioxidant activity, total flavonoids and polyphenols content and content of total water-soluble and reducing saccharides were determined by spectrophotometric methods. HPLC was used for lactic and L-ascorbic acid determination, flow cytometry was used for probiotic cell content determination, culture test was used to observe viability of cells, pH was monitored. Contents of antioxidant activity and of total polyphenols content did not drastically change during the storage. Major changes were observed in total and reducing sugar content and total flavonoids content. It was observed that probiotic viability was preserved for 14 days, decrease occurred afterwards. In order to achieve as high content of probiotics as possible, it would be advisable to store probiotically enriched juices for maximum of 14–19 days at temperature of 8 °C. The highest viability was observed in JHM sample (containing apple, pear, carrot and sauerkraut juice in the same ratio). Even through viability of probiotic cells was determined as low, these presented functional beverages remain nutritionally, visually and taste-wise interesting products, which can help popularize the consumption of non-traditional local foods.
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Technologie výroby kyselých a spontánně kvašených piv
Růžička, Vojtěch
This work aims to summarize the technological processes used in the production of sour and spontaneously fermented beers. The theoretical part of the work is focused on the technology of souring and application of bacteria and yeast species that lower the pH of beer and that were found in both, traditional historical sour beer styles and modern production of these specific beers. Subsequently, the work focuses on technological processes of brewing traditional spontaneously fermented beers and their categorisation into the specific beer styles, together with overall characteristics of the styles. At the end of the work, an experiment of brewing a fruited sour with cherries is described. This sour beer was aged in an oak barrel that was previously used for the red wine production.
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Studium inhibice mikroorganismů ve vinařské technologii
Vavřiník, Aleš
The diploma thesis deals with the study of the inhibition of microorganisms that are associated with wine technology. The emphasis is mainly on acetic and lactic acid bacteria. It deals with the research method of data dealing with the characteristics, taxonomy and metabolism of both mentioned groups of bacteria. It also describes in detail the most important representatives of vinegar and lactic acid bacteria. In the experimental part, the inhibitory properties of silver particles, which were produced by the so-called green synthesis, were investigated. Antibacterial properties were examined on two representatives of acetic acid bacteria (Gluconobacter oxydans CCM 3618 and Acetobacter aceti CCM 3620T) and two members of lactic acid bacteria (Lactobacillus brevis CCM 1815 and Pediococcus damnosus CCM 2465). Experiments have shown the inhibitory ability of silver particles against all tested bacteria, while greater sensitivity was observed in acetic acid bacteria.
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Evaluation of probiotic dairy products on the market
ŠTROBLOVÁ, Petra
Fermented dairy products with probiotics belong to functional foods, besides their nutritional value they also have beneficial effects on our health, which are mainly based on the content of lactic acid bacteria and probiotic microorganisms. The aim of the thesis was i) to evaluate information concerning fermented dairy products and probiotics among the general public through a questionnaire survey ii) to assess the offer of fermented dairy products with probiotics in five retail chains (Globus, Terno, Tesco, Billa and Trefa). Out of a total of 972 respondents, the majority (96%) reported that they consume fermented dairy products. The most popular fermented dairy product is yoghurt (87%). The majority of respondents (61%) prefer plain products. The choice of fermented dairy products when purchasing is mostly influenced by the taste of the product (607 responses), its price (461 responses) and previous experience (423 responses). Most respondents correctly knew that regular consumption of fermented dairy products improves our digestion (730 responses) and supports the immune system (562 responses). The retail chains offered a total of 147 products (70% of which were plain). The products came from 18 producers (of which only three were foreign). From the information on the products, it was found that the following probiotic micro-organisms were added by the producers to their products: Lactobacillus acidophilus, L. casei, L. rhamnosus, L. paracasei, Bifidobacterium spp. and Streptococcus thermophilus. However, the most commonly used genus is Bifidobacterium.
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Factors affecting stability and consumer acceptance of sauerkraut water
Vašků, Barbora ; Mikulíková, Renata (referee) ; Márová, Ivana (advisor)
This diploma thesis is focused on the optimization of pasteurization of the cabbage juice in order to extend its shelf life. The theoretical part is focused on the description of the sauerkraut production technology and characterization of the main components of fermented cabbage and its juice, it also deals with pasteurization options and presence of probiotic strains. In the experimental part, the composition of the brine was analyzed from a chemical point of view (bioactive substances, sugars, carbohydrates), from a microbiological point of view (presence of probiotics, pathogenic organisms) and the effect of selected pasteurization processes on these components. Pasteurization at 90 °C for 0.5 minutes was determined as the most suitable treatment, during which potential pathogens are being eliminated, while most of the original bioactive components are preserved. After suggesting the effective pasteurization treatment, suitable species of genus Lactobacillus was selected to enrich the cabbage juice product because of decreasing of probiotics viability during pasteurization treatment. The strain Lactobacillus plantarum was determined as the most suitable probiotic species for cabbage juice enrichment, due its ability to survive in 2 weeks storage at 8 °C in cabbage juice. Chemical composition after 2 weeks of incubation with mentioned organism has changed. Quantity of lactic and acetic acid increased, while no changes in content of vitamin C were observed. Finally, sensory analysis was performed to evaluate suggested mixed fruit-vegetable drink. According to results of sensory analysis, the drink composed of cabbage juice and apple-beetroot juice in the ratio of 2:1 was found as the most acceptable.
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Probiotics, their influence on health and probiotic food
Hondlíková, Tereza ; Dostálová, Jana (advisor) ; Plocková, Milada (referee)
Probiotics are living microorganisms which show positive effects on human health if consumed in a sufficient quantity. Probiotics have been under a lot of research recently, however their effectiveness in terms of treatment or prevention of diseases has not been supported by a sufficient number of studies and research yet. The thesis summarizes the existing knowledge about probiotics, characterizes individual types of probiotic organisms, describes possible sources of probiotics and their impact on human health. Theoretical part of the thesis deals with the definition of the concept of probiotics, also describes prebiotics and synbiotics which are closely related to this topic. characteristics of individual groups of probiotics as well as their impact on human health and possible use in the treatment of diseases as a form of biological treatment are also included. Furthermore the sources of probiotics both in the form of foods containing probiotics and in the form of probiotic dietary supplements are described. At the end of the theoretical part, recommendations for receiving and selecting a suitable source of probiotics are summarized. The aim of the practical part was to find out if the general public is aware of probiotics. Questions about preferences in the selection and consumption of...
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Vliv biologického a chemického ošetření na výskyt biogenních aminů u vojtěškových siláží
Remerová, Pavla
In the experiment, the influence of two different biological silage additives (Lactococcus lactis (NCIMB 30117), Lactobacillus plantarum (DSM 16568), Enterococcus faecium (DSM 22 502 / NCIMB 11181), the enzyme xylanase EC 3.2.1.8.) And chemical (43% formic acid 30% ammonium formate and 10% propionic acid and 2% benzoic acid) at a concentration of biogenic amines, nutrient content, evaluation of the quality of the fermentation process and microbiological parameters for alfalfa silage (Medicago sativa). Silage fermentation time was 90 days. Biological silage additive significantly increased incidence of putrescine (51%; P <0.05), lactic acid (11%; P <0.05), protein (11%; P <0.05). Conversely, there was a significant reduction cadaverine (29%; P <0.05), histamine (57%; P <0.05), spermidine (15%; P <0.05), spermine (55%; P <0.05), acid acid (40%; P <0.05), ethanol (55%; P <0.05) ammonia (25%; P <0.05), and ash (9%; P <0.05). In the group treated by chemical silage additive is statistically significantly increased histamine content (63%; P <0.05) and tyramine (34%; P <0.05). Decreases in the concentration of putrescine (18%; P <0.05), cadaverine (55%; P <0.05), spermidine (47%, P <0.05), spermine (45%; P <0.05), lactic acid ( 16%; P <0.05), acetic acid (46%; P <0.05) ammonia (59%, P <0.05), ash (13%, P <0.05) and fat (24%, P < 0.05). From a microbiological point of view have been affected by the lactic acid bacteria, molds, yeasts, enterobacteria and total number of microorganisms. The results show that to maintain hygiene and healthy silage is preferable to use biological and chemical silage additives. For alfalfa silage inoculant chemical has higher efficiency in maintaining health security silage compared with biological inoculant
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