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Use of some encapsulation techniques to controlled release of active substances in food and cosmetics products.
Skoumalová, Petra ; Rittich, Bohuslav (referee) ; Kráčmar, Stanislav (referee) ; Márová, Ivana (advisor)
The presented doctoral thesis is focused on preparation, characterization and application of organic micro- and nanoparticles as transport systems for active components and some their complex natural sources. Active component were packed into liposomes and polysaccharide particles. As active components were used caffeine, some drugs – clotrimazole and ibuprofen, further antioxidants and vitamins. Antimicrobial herbs and spices extract, antimicrobial peptides lysozyme, nisin and other antimicrobial ingredients were encapsulated too. Encapsulation of selected hydrolytic enzymes was tested, too. Particles were also used for encapsulation of probiotic strains Bifidobacterium breve and Lactobacillus acidophilus and prebiotic components. These prebiotics were co-encapsulated into capsules with probiotic cells. Natural extracts were encapsulated e.g. extracts of guarana, ginseng, goji, green barley, propolis, black, green and white tea, coffee, fruit and vegetable extracts. The efficiency of encapsulation was determined by HPLC/PDA and by spectrophotometry. Long-term stability of particles and amount of released component in model/real foods, in model cosmetic conditions and in a model physiological environment were monitored too. Size of prepared liposomes and polysaccharide particles was determined by dynamic light scattering and by light microscopy and electron microscopy, respectively. Stability of the particles was measured using a zeta potential. Also, analytical centrifugation was used to measurement of sedimentation velocity and stability of the prepared particles. The antimicrobial activity were tested using two Gram-positive (Bacillus subtilis, Micrococcus luteus), two Gram-negative (Escherichia coli, Serratia marcescens) bacteria and one fungal strains (Candida glabrata). For determining the antimicrobial properties of active component and prepared particles two the most widely used methods were used - agar diffusion method and broth dilution method. The viability of probiotic strains were performed using flow cytometry and fluorescence microscopy. Encapsulation of active component was successful in all types of particles. Liposome showed a very good long-term stability mainly in water conditions with neutral pH and polysaccharide particles were stable in acidic conditions. Prepared particles showed a very good stability in model stomach environment, while in model intestines environments particles were disintegrated and active component were released. Prepared particles with encapsulated caffeine as well as other tested antioxidants and vitamins could be used to modern types of energy drinks, food supplements and also for some cosmetics applications. Encapsulated antimicrobial components could be used for food application as well as for cosmetics and pharmaceutical application like antimicrobial wound formulation. Encapsulated enzymes can be used for controlled release of proteases in wound healing, as delivery systems in digestive tract and as a part of pharmaceutical preparative and food supplements for enzyme therapy. The study revealed that encapsulation of probiotics and also co-encapsulation of probiotics with prebiotics exhibited longer stability of particles and survival bacterial cells. So, prepared particles are suitable for use to food product with beneficial effects on the human body.
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Controlled prodution of pullulan by yeast-like organism Aureobasidium pulluans
Skoumalová, Petra ; Obruča, Stanislav (referee) ; Márová, Ivana (advisor)
Bachelor's thesis is focused on study of influence of exogenous stress factors on biomass and pullulan production by microorganism Aureobasidium pullulans. As a part of this work an overview of stress factors, pullulan producers, its structure, function and technological use was introduced. In the experimental part growth characteristics of Aureobasidium pullulans and pullulan production during growth in optimum conditions and under stress were analyzed. The reduced availability of oxygen resulted in a decrease of biomass production accompanied by increased pullulan production. Chemical stress induced by NaCl significantly affected mainly biomass production. The highest production of pullulan was found at 15 g / l of NaCl. Ethanol stress exhibited growth inhibition and at higher concentration also lack of pullulan production. Peroxid stress exhibited no effect on pullulan production. Short-time exposure to low heavy metal concentration (Se(IV), Cr(III)) influenced pullulan production more positively than long-term effect.
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Preparation and characterization of nanofiber wound dressings
Jiroušková, Pavla ; Uhlířová, Renata (referee) ; Skoumalová, Petra (advisor)
The presented bachelor thesis deals with the preparation and characterization of nanofiber wound dressings. The materials used for the preparation of nanofibers were poly(3-hydroxybutyrate) and gelatin. Active substances, such as ampicillin and ibuprofen, were incorporated into the wound dressings. In the theoretical part of the work skin, wound healing, and nanofibers and their properties were described. This part also deals with the use of nanofibers as wound dressings. Additionally, it depicts materials suitable for the preparation of nanofiber wound dressings. Furthermore, this section contains a review focused on various methods of preparation of nanofibers, drugs that can be incorporated into the fibers and the subsequent determination of the safety of the prepared dressings. In the experimental part, nanofiber wound dressings containing ampicillin and ibuprofen were produced. The maximum possible amount of active substance feasible to be incorporated into the nanofibers has been determined. Subsequently, combined wound dressings were prepared to study the release rate of active substances into the model environments. The release in the time intervals was determined spectrophotometrically. Finally, antimicrobial activity assays were performed to test the effect of dressings containing ampicillin on selected strains of microbiirganism: S. Epidermidis, E. Coli and M. Luteus
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Antimicrobial materials based on nanostructures with enzymes
Jurová, Bronislava ; Vysoká, Marie (referee) ; Skoumalová, Petra (advisor)
This bachelor thesis is focused on the preparation and characterization of antimicrobial gels and coatings containing antimicrobial components and enzymes. The theoretical part deals with a brief description of antimicrobial substances, their structure and mainly enzymes with antimicrobial effect. The methods used in the testing are also listed here. The practical part deals with testing the antimicrobial effects of extracts from cinnamon and cloves, clove essential oil, lysozyme and bromelain against Micrococcus luteus, Serratia marcescens and Candida glabrata. Various types of extracts were prepared from the selected spices, namely aqueous and ethanol extracts in different percentages. The individual extracts were characterized and, according to the total proportion of phenolic substances, the best ones were selected for encapsulation in liposome particles and gels. Extracts and enzymes were also added to the hydrogel and non-fibrous covers. A solution of sodium alginate and chitosan was used to prepare non-fibrous covers. A broth dilution method was used to test the antimicrobial effects on the given microorganisms. Furthermore, nanofibers based on PHB were prepared using the forcespinning method. These nanofibers were enriched with clove essential oil and their antioxidant activity was monitored.
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Involvement of polyhydroxyalkanoates into stress response of bacteria
Kučera, Dan ; Skoumalová, Petra (referee) ; Obruča, Stanislav (advisor)
The aim of this work was to study the involvement of polyhydroxyalkanoates (PHA) into stress response of bacteria. The theoretical part of the thesis deals with the possibility of establishing the viability of microorganisms using modern techniques, in particular flow cytometry. Furthermore, the research focused on selected stress factors and PHA involvement in stress response was described. In the experimental part of the work the stress response with regard to the ability to accumulate PHA was assessed. Bacteria Cupravidus necator was used for the experiment. Its ability to accumulate PHA at a later stage of growth increased resistance to ethanol, high temperature and freezing. Conversely, the PHA-producing strain showed lower resistance to the action of inorganic acids and bases. This may be caused by different morphology of PHA-producing cells. One of partial objectives was also to study the possibilities of staining of living cells accumulating PHA using Nile red. The research proved that the dye penetrates into living cells at elevated temperature of 40-45°C. This temperature is not lethal to the cells and the intensity of staining is sufficient to distinguish PHA-producing cells using flow cytometry; that can be applied in the selection of industrial PHA producers.
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Study of bioactive compounds of fennel
Mierna, Jana ; Skoumalová, Petra (referee) ; Veselá, Mária (advisor)
The master´s thesis is focused on the study of biologically active compounds of fennel. The theoretical part describes basic characteristics of fennel and its chemical composition, further specifies plant´s biological active substances and antioxidants, also describes extraction techniques for obtaining these bioactive compounds, methods of their determination and verification of antimicrobial effect. In the experimental part were spectrophotometrically determined contents of polyphenols and flavonoids in the prepared extracts of fennel tea, whole and crush spice. On the basis of extraction curves, antioxidant activity and potential antimicrobial activity against the selected microorganisms Bacillus subtilis, Bacillus cereus, Serratia marcescens a Micrococcus luteus was determined in the samples with the highest values of the given bioactive substances. Among the all monitored extracts, the inhibitory effect was showed only by an aqueous extract of the fennel tea against the bacterial strain of Micrococcus luteus.
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Encapsulation of probiotics and prebiotics for use in nutritional products for children
Šnajdarová, Karolína ; Němcová, Andrea (referee) ; Skoumalová, Petra (advisor)
The Diploma thesis deals with designing of probiotic dietary supplement for children with strains Lactobacillus acidophilus and Bifidobacterium breve and with prebiotics. Used prebiotics were Inulin, Chia fiber, Bamboo fiber, Chlorella + Spirulina and Yakon syrup. The theoretical part is focused on probiotics, prebiotics and their biological influence. In experimental part the possibilities of encapsulation into alginate particle and lyophilisation of probiotic cells were observed to find their good form to final nutritional product for children. Several types of probiotic with addition of prebiotics were tested in model conditions of gastrointestinal tract. It was found that addition of prebiotic highly increases viability of probiotic cells and their resistance to model conditions of gastrointestinal tract. In this case, the best prebiotic was found in Yakon syrup. The prebiotics were also characterised in terms of nutritional composition, amount of total and reducing sugars, oligosaccharides, proteins, lipids, polyphenols and chlorophyll were obtained. Finally, Chia fiber, Chlorella + Spirulina and Yakon syrup were chosen as prebiotics with best characterisation/properties. In conclusion, a dietary supplement with lyophilized alginate particles containing probiotic cells and with the most appropriate prebiotics were designed. Forms of the product were powder and gummy-bear.
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Study on potential applications of glutamic acid polymer
Čangelová, Katarína ; Skoumalová, Petra (referee) ; Obruča, Stanislav (advisor)
The subject of the thesis is study of possible applications of isoform of glutamic acid polymer (-PGA). The theoretical part is focused on the properties of this biopolymer and potential applications in various areas. Producers and mechanisms of biosynthesis are also mentioned. In the experimental part, the polymer was firstly characterised by following methods: FT-IR spectroscopy, TGA, DSC and SEC-MALS. Its isoelectric point, antimicrobial activity and solubility in various solvents were also determined. The biopolymer was also precipitated by divalent cations and its interaction with oppositely charged CTAB surfactant was studied. The main experimental study was researching the effect of -PGA on viability of Saccharomyces cerevisiae and Lactobacillus rhamnosus under stress conditions by flow cytometry. The performed stresses included ethanol exposure, high temperature and freezing stress, in which its effects were compared to conventional cryoprotectants. The cells of the mentioned microorganisms were also stressed osmotically and exposed to model gastrointestinal juices - gastric, pancreatic and bile. The protective effects of -PGA on the cells were recorded in ethanol stress on Lactobacillus rhamnosus. Its excellent cryoprotection properties were confirmed and its protective effect of gastric juice exposure on Saccharomyces cerevisiae cells was also observed. At the end of the experimental part, -PGA/alginate beads suitable for encapsulation of probiotic bacteria and -PGA/chitosan nanoparticles for encapsulation of biologically active substances.
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Significance, occurrence and determinants of horizontally transmissible colistin resistance in Gram negative bacteria
Kislíková, Karolína ; Skoumalová, Petra (referee) ; Márová, Ivana (advisor)
Colistin, also known as polymyxin E, is antibiotics active against most of Gram-negative bacteria. In the pas decade, emergency of multidrug-resistant bacteria led to increase of colistin administration as a last resort antibiotic for human infections. The first plasmid-mediated colistin resistance gene mcr-1 was identified in 2015 in animals in China and after first detection, additional mcr genes: mcr-2, mcr-3, mcr-4, mcr-5, mcr-6, mcr-7 a mcr-8 were described throughout the world. The aim of this thesis was to clarify whether there is horizontal transmission colistin resistance encoded by the mcr genes in gram-negative bacteria isolated from the environment, animals and their breeding and food. The mcr-1 gene was detected in 2 strains Escherichia coli isolated from waste water. The mcr-4 gene was detected in 1 strain Shewanella putrefaciens isolate obtained from the lake. The environment is the most important source and way of spreading this type of resistance in the Czech Republic.
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Preparation and characterization of foods and food supplements containing selected vitamins
Krupičková, Lucie ; Hoová, Julie (referee) ; Skoumalová, Petra (advisor)
The thesis is focused on preparation of protected form of vitamins for aplication to food and diatery supplemets. The theoretical part characterizes vitamins and describes their role in human organism. Furthermore, this chapter summarizes different methods of determination vitamins soluble in water and encapsulation of substances into liposomes. The last sections are focused on functional foods and dietary supplements. In experimental part, an optimalization of determination method was made. Selected vitamins were encapsulated into liposomes. Size, stability, encapsulation efficiency, long-term stability and long-term encapsulation efficiency after two weeks was determined there. All prepared liposomes were found to be stable enough. Furthermore, the vitamin solutions, liposomes and lyophilized particles were analyzed during the process of model digestion. The active forms of vitamins were degraded during the model digestion of vitamin solutions. Vitamins were gradually released from the liposomes and lyophilized particles into the digestive juice. The analysis of content declared by producer was executed for functional foods and dietary supplements. Finally, applications of protected form of vitamins into the food and dietary supplemets were created.
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