Storage mite Acarus siro is one of the most distributed stored product mites in the world. It infests various products (grains, dried fruits, meat products, animal feed etc.) and causes allergic reactions in humans. For these reasons, it is important to find an effective strategy to suppress or even better to eliminate the mite from the storing facilities. Historically, there have been reported cases of the mite being resistant to several pesticides. In this thesis, four populations of Acarus siro were exposed to pesticides in different concentrations - first in the form of solutions and next as a diet additive. The populations showed divergent sensitivity to four selected pesticides (pirimiphos-methyl, chlorpyriphos-methyl, deltamethrin and deltamethrin in combination with piperonyl butoxide). The biggest differences were recorded in response to solutions of pirimiphos-methyl. This pesticide was then added to standard rearing diet in five concentrations. The mite populations were exposed to this died for 3 weeks. Control and pesticide-treated diet microbiome analyses revealed that 0.0125 µg×g-1 concentration causes hormoligosis in 6L and 6Tu strains. The same concentration was responsible for microbiome change in 6Z strain. Exposure to 1,25 µg×g-1 concentration caused microbial shifts in 6Z and...

The topic of this thesis has been built on previous work of our group, especially Rieger et al. 2008 and Čepl et al. 2010. We examined and described the regularity of morphogenesis of S. marcescens, morphotype F colonies (from "the fountain", because of a shape it resembles). Typical colony consists of elevated red navel, low non-pigmented ring and again elevated red rim. Structured profile of the colony together with changes in pigmentation of structures during development without need of artificial dying, provides considerable advantage in observation of the morphogenesis. Aims of this thesis were (i) to find other factors that affect the morphogenesis, (ii) to characterize interactions of S. marcescens colonies with other bacterial strains (S. rubidaea and E .coli) and finally (iii) to study the phenomenon of induced resistance to the antibiotics described in (Heal and Parsons, 2002; Lu 2004; Bernier et al. 2011) in our model organisms. (i) Mutual interactions of colonies on the plate indicates that morphogenesis is affected by autocrine signals, which diffuse into the medium and the atmosphere and affect the development of surrounding colonies. We have detected changes of pH of the medium during the development of colonies in their vicinity. At ...

This thesis deals with microbial contamination of herbal teas. The theoretical part is focused on medicinal plants, their growing, harvesting and herbal tea production. This part also includes legislative requirements for herbal teas and characterize microorganisms that could be in herbal infusions found. It also describes the processes that can reduce microbial contamination. Experimental part summarizes the results from laboratory work, which was focused on microbial contamination of herbal teas. It shows the effect of boiling water on the number of microorganisms in herb teas and herbal infusions. Due to the time were examined the changes in the number of microorganisms in herbal infusions.

This dissertation deals with the influence of active substances from plants on lactic acid bacteria. It describes milk in terms of nutrition, sour milk products which can be made by means of using lactic acid bacteria, division and overview of lactic acid bacteria, substances contained in plants and the effects of four selected plants. The aim of this work was to determine the possibility of antimicrobial effects of caraway, cinnamon, sage and thyme on bacteria. The efficiency was performed on genus of Lactobacillus. The determination of change in inhibition was performed by disk diffusion method and determination of turbidity.

This thesis consists of six research chapters, out of which, five have already been published in research journals, 1 is in the process of submission and the last chapter presents original unpublished confidential data in the process of manuscript preparation. The research presented in this thesis concerns the complex mechanisms of bees and wasps immune system focused on microbiota as component of immunity. As shown in the introduction, highly social and managed species of bees like honey bees and bumble bees, play key roles in natural and agricultural ecosystems worldwide. Recent losses of bees have been attributed to pesticide exposure, poor nutrition, increased parasite loads and habitat degradation. Over the past several years, governments, beekeepers, and the general public worldwide have become concerned by increased losses of honey bee colonies, calling for more research on how to keep colonies healthy. Our main aim was to explore the complex mechanisms of bees and related species gut bacterial populations, their links to insect immunity and investigate the opportunities for an intervention. Part of our aim was to characterise the bumble bee and wasp gut microbiota using 16S RNA sequencing in a search for potentially novel bacterial species. We have tried to explain how microbiome interacts with the host and showed that major members of these communities appear to benefit the host. The simple gut communities of social bees present ideal model systems to investigate the underlying evolutionary and genetic processes of such interactions. Information based on our results may help in the design of proper probiotic supplementation strategies with respect to physiological conditions in the honey bee gut.

The diploma thesis investigates antimicrobial effects of plant extracts (ethereal oil) on microorganisms extracted from milk and milk products. The theoretical part focuses on joghurt and its production, main pathogenic microorganisms and their secondary metabolites affecting health. It presents antimicrobial effects of selected plants and procedures minimising or completely inhibiting the growth of microorganisms. Thyme and anise serve as the evidence for antimicrobial agents; the inhibitory effects of these ethereal plants were observed on the growth of selected microorganism groups (lactic acid bacteria, coliform bacteria, Enterococcus bacteria and yeast) by using disc diffusion test method. The RTS - 1C machine was used to simulate model conditions. Thyme ethereal extract with concentration of 1 and 10 % was used for disc diffusion test method. Anise ethereal extract with concentration of 0,7 % was used for observation of microorganisms' growth in model conditions.

This dissertation deals with evaluation and testing of food packiging materials antimicrobial aktivity that contain plant extracts and help in the fight against Eschericia coli and other coliform bacteria. This dissertation is divided into several parts. The first half of the work contains a literature review publishing about packaging materials containing plant extracts. It is also focused on literature review on the coliform bacteria, especially Escherichia coli genus, describes these microorganisms and their metabolic products, the effects of metabolic products which may negatively affect human health. Another part deals with measures to prevent undesirable microorganisms. The second half of the work has been engaged in actual testing of packaging materials containing plant extracts on relevant model organisms or directly on food. Data, acquired by testing are processed, compared with the figures in the available literatures and are listed at the end of work.

This thesis on a Method for extending the shelf-life of dairy products in its theoretical part with milk and milk products, in special chapters separately with fresh cheese - their general process of production and possible defects. Furthermore, the theoretical part deals with the reasons for spoilage of dairy products, due to the external environment on microorganisms. These include in particular the temperature, pH and water activity. The other chapters are focused on different basic methods for extending shelf-life, which are often used in dairying. These include antimicrobial agents, lactic acid bacteria. Lactic acid bacteria is devoted to a separate subhead with protective lactic acid bacteria. The last part of the theoretical thesis is focused on hygiene, which to make cheese inseparable. The practical part of this study looked at the effects of protective cultures added to fresh cheeses. In dairy pilot plant were produced four kinds of cheese - three different types of protective cultures, one with classic cream culture. Samples were always salted and unsalted. All samples were then evaluated by chemical and microbiological analysis to determine the effect on shelf life.

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