Presented work was focused on biodegradability of bacterial natural and modified polyesters and their composites. The first part of the work was focused on study of influence of PHA granules structure on their biodegradability using selected enzymes and influence of physiological conditions on PHA stability. Overall, tested polymer either in crytalinne or amorphous phase seems to be rezistent to attack of seleced hydrolytic enzymes such as lipases or proteases and is stable in simulated physiological fluids as well. Because of thies results, it is possible to use tested PHA materials in biomedical applications requiring rather resistant biomaterials. Second part of the work was focused on microbial degradation of modified PHA materials considering their potential environmental impact. Both mixed thermophillic culture originaly used in wastewater treatment plant and bacterial strain Delftia acidovorans were employed for biodegradation tests. Composites containing chlorine PHB and PHB films modified using plasticizers were tested. Films containing chlorine PHB cause inhibition of biomass growth to both tested cultures. The highest rate of degradation (31%) was observed in presence of bacterial culture with film containing 10% chlorine PHB. The results show that used microbial population is important factor affecting biodegradability.

The master‘s thesis is focused on the study of biodegradation of polyhydroxyalkanoates, namely polymer polyhydroxybutyrate. The first part of the thesis is focused on the study of biodegradation of polyhydroxybutyrate in the form of crystalline granules of PHB and PHB films using selected species of microorganisms from bacteria, yeasts and fungi. As a representative of bacteria was chosen microorganism Delftia acidorovans, as yeast was selected Aureobasidium pullulans and Aspergillus fumigatus as fungi. PHB depolymerase activity was measured employing turbidemtiric method with suspension of PHB granules as substrate. The results showed that D. acidorovans can partially degrade PHB. On the contrary A. pullulans cannot effectively degrade PHB. The most significant degradation ability revealed A. fumigatus, which was able to degrade PHB completely. Extracellular enzymes excreted by these microorganisms when cultivated on PHB materials as sole carbon sources were analyzed by SDS-PAGE. The second part of the thesis deals with the biodegradation of PHB in the form of PHB film, PHB hardened foil and PHB Nanoul fabric using standard composting test. Semi-solid cultivation showed positive results. In the interval from 14 days to two months were all forms of the PHB completely biodegraded. With semi-solid cultivation was also studied biodegradation rate of the polyurethane elastomeric films which were modified by partial replacement of polyester polyol by PHB. The test samples were prepared using PHB from Sigma and the PHB samples prepared at the Faculty of chemistry VUT. Samples with different concentrations of the dispersed PHB (1 %, 5 % and 10 %) in the polyurethane were also object of the study. At the end of the cultivation (after 2 months) were measured mechanical properties in tension of the material, then efficiency of biodegradation by gravimetric analysis and modification of the material surface by microscopic analysis.

Aromatic pollutants pose a serious environmental problem. Petroleum and its derivates belong to the most abundant contaminants in the Czech Republic and their sanation is a priority objective for improving the life quality of the population. Bioremediation is a technology taking advantage of the natural capacity of soil and water microbial community to degrade environmental pollutants. Deeper understanding and detailed knowledge on specialized bacterial species, pathways and genes is required for selection, optimization and application of targeted bioremediation approach and for monitoring of its results. Recent analysis of a metagenomic library constructed from highly contaminated soil of the former military air-base Hradčany has identified a novel group of catabolic genes encoding extradiol dioxygenase similar to DbtC of Burkholderia sp. DBT1. The DbtC-like enzymes are among the three priority groups of extradiol dioxygenases with biodegradation relevance for the locality. The present study of soil bacterial isolates and metagenomic fosmid clones harboring the genes of interest gained evidence about the dbtC-like genes as a part of highly mobile gene cassette. Transposon insertion mutagenesis identified the genes joined with the expression of the extradiol dioxygenase activity. The dbtC-like genes were...

The key tool for tissue engineering is the scaffold that supports cells for new tissue growth. Materials used for creating scaffolds are based on polymeric materials, carbon nanofibers, ceramics, and metals and their alloys. In my thesis, I describe the synthesis and characterization of new biodegradable hydrogels containing biodegradable crosslinks and biodegradable nanofibrous materials intended for scaffolds for tissue engineering. I also describe the preparation of macroporous hydrogels intended for neural tissue healing. In the first portion of this thesis, I examine a hydrogel based on a pH- responsive crosslinker. This hydrogel is stable at basic and neutral pHs but is degradable at pH < 7.4. The degradation rate of this hydrogel can be tailored. This hydrogel can be utilized as an esophageal stent or as a targeted drug release system in the stomach. The second portion of this thesis focuses on a biodegradable hydrogel designed for neural tissue repair. This hydrogel is composed of copolymers of N-(2- hydroxypropyl)methacrylamide and a newly synthesized biodegradable crosslinker based on 6,6'-dithiodinicotinic acid. This hydrogel can be stored in a neutral environment without degradation. Its long-term storage capability is another great advantage for clinical applications. During storage,...

Charles University, Faculty of Pharmacy in Hradci Králové Department of: Pharmaceutical technology Consultants: Jana Kubačková, Ondřej Holas Student: Jáchym Vencl Title of Thesis: Optimization of polymeric nanoparticles separation and purification protocol Poly(lactic-co-glycolic) acid (PLGA) is one of the most successful polymeric molecule invented for biomedical use. PLGA's biggest advantage lies in its biodegradability and nontoxicityChyba! Záložka není definována.. It has been approved by EMA for human use. Because of increasing number of protein or nucleic acid based drugs the need for sophisticated drug delivery systems grows. PLGA nanoparticles (NPs) present exactly such drug delivery system capable of encapsulating large variety of compoundsChyba! Záložka není definována.. Within this study we have researched optimization of separation and purification of drug loaded NPs. They were prepared by nanoprecipitation of PLGAChyba! Záložka není definována.. Separation and purification of NPs was done using multiple cycles of centrifugation. We evaluated purification of particles prepared from five different PLGA polymers. Different centrifugation times were applied to find the most effective way. Water and two types of stabilizers each one in two concentrations have been used as purification...

Presented diploma thesis focuses on a new type of lightweight polyurethane foam (PUR), which has been manufactured with the intention of it being biodegradable within currently valid norms on biodegradation of plastic materials. The future use of said polyurethane foam is as carrier for odor repellent to avoid wildlife-vehicle collisions in agriculture landscape, where, after the end of its lifespan it could be left to biodegrade in soil the environment. The examined material, PUR BIO-10, was tested for biodegradability in laboratory microcosms according to standardized method ASTM D5988-03. Biodegradability was tested in two separate soil types - forest soil and agricultural soil, which have been selected with the future use of the material in mind. According to the method biodegradability was measured as mineralization of the material by capturing evolved carbon dioxide. During the first trial the mineralization of polyurethane foam was 10.65 ± 2.54 % in the forest soil and 20.48 ± 9.18 % in the agricultural soil. During the second trial the mineralization was 3.88 ± 3.42 % in the forest soil and 8.96 ± 1.79 % in the agricultural soil. In the second trial the difference between the soils was statistically significant. After the end of the biodegradation experiments the tested material was...

Candida tropicalis yeast is a microorganism that possesses high tolerance for phenol and strong phenol degrading activity. This yeast is capable of utilizing phenol as the sole source of carbon and energy without formation of any secondary waste product. Catechol-1,2- dioxygenase was isolated from cytosolic fraction of this yeast by the procedure consisting of chromatography on DEAE-Sepharose and gel permeation chromatography on Sephadex G- 100. The catechol-1,2-dioxygenase was purified to homogeneity. The enzyme activity was followed by HPLC (catechol consumption and/or cis,cis-muconic acid formation). The activity profiles at different temperatures showed temperature optimum of 30řC. Kinetic characterizations were studying in different values of pH. The values of Km and Vmax of 0,52 mM and 17,2 nM/min for consumption of catechol, respectively, and 0,34 mM and 12,6 nM/min for formation of cis,cis-muconic acid, respectively, were found at optimum pH of the reaction, pH 7,6.

In the recent years, many research articles focused on endocrine disrupting compounds in the environment. Some of these compounds are listed in a group named brominated flame retardants. However, only few articles investigated endocrine activity of several "new" brominated flame retardants. These chemicals such as 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) or bis(2-ethylhexyl) tetrabromophthalate (TBPH) are newly used due to ban of some previously most produced brominated flame retardant mixes. In this study, we used two recombinant yeast screens to measure estrogenic, androgenic, antiestrognic and antiandrogenic activities of some alternative brominated flame retardants. We also used ligninolytic fungi to investigate biodegradation of these compounds. Our results suggest, that 2,4,6-tribromophenol (TBP) may be a new environmental endocrine disruptor. This substance showed antiestrogenic and antiandrogenic activity in our tests. 1,2-bis(2,4,6- tribromophenoxy)ethane (BTBPE) had certain antagonistic activity too. In the biodegradation experiment, only three compounds showed significant degradation during the test period. No biodegradation have been observed for other compounds. In this study, we applied gas chromatography with mass spectrometry to analyze these "new" flame retardants. Method for gas...

Sulfonamides are antibiotics that are frequently used both in human and veterinary medicine. The combinations of abundant use of these antibiotics and their natural resistance to decay leads often to long term persistence in the environment. This accumulation, especially in living organisms, may lead to subsequent toxicosis. Also, presence of these antibiotic in nature poses problems with regard to the spread of genes for antibiotic resistance between potential pathogens. These facts led to an increase interest in studying the sulfonamide biodegradation and subsequent sulfonamide removal from the environment. In this work it was possible to isolate and characterize the microorganism Acinetobacter sp. strain 49. This microorganism was able to biodegrade under right conditions sulfamethoxazole with 80 % efficiency. Sulfamethoxazole is one of the most commonly found sulfonamide in the nature.

Presented diploma thesis focuses on a new type of lightweight polyurethane foam (PUR), which has been manufactured with the intention of it being biodegradable within currently valid norms on biodegradation of plastic materials. The future use of said polyurethane foam is as carrier for odor repellent to avoid wildlife-vehicle collisions in agriculture landscape, where, after the end of its lifespan it could be left to biodegrade in soil the environment. The examined material, PUR BIO-10, was tested for biodegradability in laboratory microcosms according to standardized method ASTM D5988-03. Biodegradability was tested in two separate soil types - forest soil and agricultural soil, which have been selected with the future use of the material in mind. According to the method biodegradability was measured as mineralization of the material by capturing evolved carbon dioxide. Two trials with different treatments were executed. In the first trial the material was introduced directly into the soil and in the second trial the material was tested in a litterbag to avoid soil contamination which was problematic for further analysis. During the first trial, after 90 days, the mineralization of polyurethane foam was 10.65 ± 2.54 % in the forest soil and 20.48 ± 9.18 % in the agricultural soil. During the...