Polychlorinated biphenyls (PCBs) are chlorinated organic compounds, which belong to persistent organic pollutants and exhibit various modes of toxic action, including mutagenicity, carcinogenicity, and endocrine disruption. PCBs were manufactured during the 20th century in many countries and extensively used due to their advantageous physicochemical properties. PCBs mostly served as insulating liquids in electrical equipment; however, they were also utilized in many open applications. Despite the worldwide ban on PCB manufacture imposed at the end of the 20th century, the contamination of the environment persists to this day as a result of their recalcitrance. Moreover, PCBs are still being inadvertently produced during many industrial activities. Because of their stability, the breakdown of PCBs in nature is extremely slow. This dissertation thesis focuses on the study of PCB biodegradation by ligninolytic fungi. This group of microorganisms belongs to the most promising, especially in regard to the degradation of organic pollutants. The biodegradation mechanism of PCBs was studied in vitro, including the identification of degradation intermediates. Laccase, an enzyme expressed by the oyster mushroom (strain Pleurotus ostreatus 3004), was able to degrade hydroxylated PCBs. In addition, chlorinated...

This work deals with influence of heat processing on longevity of two selected products of the packing company Seliko trading a.s. For the research there were selected products Sterilised sauerkraut in sweet-sour pickle and Fatback spread. Evaluation has been done in laboratory premises of the packing company. There has been monitored mikrobiological stability after heat processing and sensory properties of the mentioned products always with an interval of one month. During the monitored seven months there appeared changes in taste and consistence of the products that are not defective in these products. The microbiological test taken after seven months was negative, just like at the beginning of the experiment. The result of the given findings is that the heat sterilisation was efficient and that during the storage there did not rise number of micro-organisms in the products.

The plant cell wall consists of several layers: cellulose, hemicellulose, lignin and pectin. These biopolymers are degraded by many microorganisms. Extracellular enzymes are used for biodegradation by microorganisms. This thesis was focused on studying the impact of cultivation conditions on the production of extracellular enzymes at carboxymethyl cellulase and pectin when a mixed thermophilic culture containing Bacillus and Thermus microorganisms is used. The cultivation was carried out in flasks on a shaking machine with a shaking speed of 99 min-1 at a temperature of 60°C. The monitoring covered cellulolytic and polygalacturonase activities, protein concentration by the Biuret method, concentration of reducing substances by the Somogyi and Nelson methods, and the temperature optimum.

Raman spectroscopy is a powerful tool for identification both inorganic and organic compounds including microbial biomolecules. Together with the fact, that it is considered to be the important nondestructive instrument for use on Mars within future robotic missions, it is necessary to assess its capabilities in scenarios relevant for both Martian and terrestrial conditions. In this work, the potential of Raman spectrometry was tested - including both bench-top laboratory systems as well as portable counterparts - to detect traces of life within evaporitic matrices through biomolecular identification. Due to their chemical and physical nature resulting in optical properties, pigments are important organic compounds in Raman spectroscopic analysis using visible excitation. Hence in this work we have focused on the Raman spectroscopic identification of pigments as biomarkers with relevance for investigation of life in both extreme terrestrial and potentially extraterrestrial environments. Results of methodical work are presented in Appendices I to III, dealing particularly with β-carotene as a model carotenoid pigment. The concentration limits of this biomarker in three different evaporitic matrices (halite, gypsum and epsomite) have been determined for artificially prepared powdered mixtures alone...

The aim of this diploma thesis „Evaluation of Selected Quality Parameters in Heat-treated Meat Products“ in the theoretical part were characterized heat treated meat products, produciton materials, production technology and description of the products packaging in detail. Furthermore were characterized microorganisms of meat and meat products which cause their destruction and factors influencing their growth were taken into account. Another part of the work was experimental and it was about the quality monitoring of two types of heat-treated meat products, divided into two batches. One of the practical part was microbiological analysis and these microorganisms were monitored: total bacteria count, the number of coliform bacteria, the total number of psychrotrophic microorganisms, the number of anaerobic endospore forming bactreia, yeasts and fungi and the amount of enterococcus bakteria. Simultaneously with microbial analysis, pH determination was performed. At the last stage of diploma thesis is statistical evaluation of the results which is monitoring the numbers of microorganisms and the pH depending on the storage period.

The dissertation is occupy with microbial settlement of black pepper, which is one of the world's most widely used spices. Characterizes each kind of pepper, discribe microorganisms occurring in spices and spice treatments. It also state legislative limits of microorganism occurrence. The practical part of this work deals with experimental determination of selected groups of microorganisms in black pepper. Analyzed samples of black pepper were purchased in business chains, sold under a known brand and private label and also in shops dealing only with spices and herbs. The results of the work shows that microbial contamination of spices is constantly decreasing and in most cases doesn’t exceed the allowed limits. The most contaminated sample belonged to private label samples, and the least contaminated sample belonged to wholesale spice distributors.

7 Abstract Close physical interspecific associations called symbioses are central for understanding both evolution and interactions of all branches of living creatures, as well as shaping the Earth's physical features - in other words, they are essential for understanding the nature of whole biosphere. Symbiotic research takes place in some variation in all fields of biology, and since the nature of the phenomenon apparently has a fundamental importance as an exceptional underlying & unifying scheme, there is growing need for appropriate theoretical analysis. Here I discuss the theoretical frame, definition and history of the concept of symbiotic interactions and its significance and use in theoretical biology. Keywords: symbiosis, life, microorganisms, evolution, metaphors and models

Microbiological quality of food is important both because of hygiene and health and has a significant influence on the shelf life of foods. The aim of this thesis was to evaluate samples of meat products for contamination by microorganisms. There was soft meat product, the product heat-processed and heat-treated. Evaluated how they affect the product and then cutting up into the vacuum packaging the total number of microorganisms, the influence of ambient temperature on the development of bacteria and the production have been using the new technology will benefit the health quality of the product. As revealed from the results, a product bar showed fewer organisms than product, which was sliced and then packaged in a vacuum. The fault was apparently slicing equipment that was not completely disinfected, and there was a transfer of bacteria. Therefore, it is necessary to improve sanitation and to see to their strict compliance. Resulting in the effect of temperature on the growth of microorganisms. The rising temperature is increased, the number of microorganisms. Use of air-conditioned chambers in the production of meat products is shown in terms of reducing the total number of microorganisms as a positive.

The thesis summarizes findings about the microbiology of goat and sheep milk and of farm produced cheese. It describes the production of selected groups of cheeses. It deals with particular microorganisms which are important with respect to technology and which are contained in primary and secondary cultures. It characterizes the undesirable microorganisms which cause contamination and it presents the possible measures to fight with them. Last but not least, there are described the legislative requirements for the farm processing of milk and cheese. The chosen groups of microorganisms were experimentally determined by cultivation methods in samples of raw goat and sheep milk and cheese. It was found out that in some months the values of CPM in milk exceeded the limit given by the Orders of the European Parliament and Counsel 853/2004. The discovered presence of enterococci, coliform bacteria, thermo-resistant aerobic and anaerobic bacteria and other undesirable microorganisms in raw milk and cheese points to the insufficient adherence of hygienic principals and technical procedure.

In this thesis I deal with the influence of storage temperature on reducing the number of microorganisms in meat products. In this work is analyzed cooling and freezing storage of meat and meat products. The next section provides an overview of the major contributors to food-borne illness (Salmonella, Escherichia coli, Campylobacter, Listeria monocytogenes, Bacillus cereus, etc.). At the end of research is the mention of the HACCP system. The research was focused on the refrigerated storage of whole (rod) sausages and vacuum packed sliced meat products, which were further divided into cooked and uncooked meat products. The thesis was evaluated the effect of changes in temperature and storage technology to the number of microorganisms in cooked and uncooked meat products.