This diploma thesis deals with the characterization of rheological properties and biodegradation of a poly(3-hydroxy-co-4-hydroxybutyrate), a copolymer produced by a strain of Cupriavidus malaysiensis. The theoretical part focuses on the rheology and degradation of polymers in general. It also contains the basic characteristics of polyhydroxyalkanoates and deals in more details with the description of the studied copolymer, its properties, synthesis, decomposition and possibilities of its applications. In the experimental part, the given copolymer was investigated in its native form and also in the form of copolymer mixtures filaments, which were enriched with additives (stabilizers and plasticizers). In terms of rheology, the samples showed pseudoplastic behaviour, which was slightly limited by the plasticization of the material. The highest thermal stability observed as a function of changes in complex viscosity over time was observed in a sample of a copolymer mixture containing stabilizers and plasticizer Citrofol BII. The plasticization also caused significant changes in thermal properties, especially crystallinity, which decreased compared to the native copolymer. In vitro degradation studies of samples in the form of films prepared by dissolving copolymer mixtures in chloroform were performed in phosphate buffer with lipase, in simulated body fluid and in synthetic gastric juice. The course of the process itself was characterized by the method of determining the molecular weight (SEC-MALLS) and the weight loss over time (gravimetrically). The results showed that the analysed samples are subject to degradation in all used environments. The most considerable molecular weight loss after 105 days (76 %) was observed in the sample containing stabilizers and plasticizer Citrofol BII in the environment of synthetic gastric juice. The most extensive gravimetric weight loss was attributed to the sample with stabilizers and without plasticizers, in the environment of phosphate buffer with lipase, specifically by 79%.

Understanding the redistribution and fate of N is essential for justification of Best Management Practices (BMP). This project was conducted on a Hecla fine sandy loam (sandy, mixed, Aquic Haploboroll) soil at the BMP field site near Oakes, North Dakota. One objective of this investigation was to evaluate the residence times of N03- -N in 20 undisturbed lysimeters and its infiltration time through the soil profile to tile drains. Corn (Zea mays L.) was fertilized with 135 kg N ha -1 as ¹⁵N-enriched urea plus 13.5 and 48.1 kg N ha -1 preplant for 1993 and 1994, respectively. Urea-N was band applied to 20 and 10 undisturbed lysimeters at 2.0 and 5.93 atom percent (at %) ¹⁵N in 1993 and 1994, respectively. Average resident times of N03- -N in the lysimeters was 11.7 months. Lysimeter and tile drainage indicate the presence of preferential pathways. Residence times of N03- -N depend on frequency and intensity of precipitation events. Another objective was to determine what portion of the total N in the crop was from applied urea-N and what portion was from the native soil-N. Nitrogen plots received ¹⁵N enrichments of 4.25 and 5.93 at % ¹⁵N in 1993 and 1994, respectively. At the end of the 1993 and 1994 growing season, 41.5% and 35.7% of the labeled fertilizer N remained in the soil profile, while the total recovery of applied ¹⁵N in the soil-plant system was 86.2% and 75.4%, respectively. Low recoveries of applied N may have been the result of soil or aboveground plant biomass volatilization, or denitrification or preferential flow processes. Further research needs to be conducted with strict accountability of gaseous loss and the mechanism(s) responsible. / U.S. Bureau of Reclamation

This thesis is focused on study of biodegradability of modified polyurethane elastomeric films in synthetic medium with minerals and vitamins on tempered shaker by mixed thermophilic aerobic bacterial culture Bacillus and Thermus genera. In most cases addition of all used fillers (carboxymethyl cellulose, hydroxyethyl cellulose, acetylated cellulose, acetylated starch and glutein) led to increased biodegradability of elastomeric films with modifying agent in comparison with elastomeric films without modifying agent (referential). The growth of cultures was strongly increased in presence of elastomeric films modified by 10 % acetylated cellulose and 10 % carboxymethyl cellulose. Elastomeric film biodegradation mechanism included probably two stages: abiotic destruction of elastomeric films and consequent utilization of degradation products by bacterial culture.

Presented diploma thesis deals with the study of ring-opening polymerization (ROP) of caprolactone catalyzed by novel organic and organometallic compounds. In the theoretical part of the thesis a summary of polymerization strategies and catalytic/initiators systems for ROP of polyesters is overviewed on the basis of reported background research. In experimental part a series of caprolactone polymerization runs with the view of polymerization conditions (solution/monomer ratio, catalyst/initiator ratio, monomer/initiator ratio and monomer concentration) at the temperature range of 25-70 °C was carried out. The experimental study was focused on catalytic precursors based on organic carbenes (tBuNCH=CHN+tBu)CH Cl- (NHC-tBu) in tetrahydrofuran solution and complex of aluminium{O,O’-[4,5-P(O)Ph2tz]-AlMe2} Ph = phenyl, tz = triazole, (OAlMe2) in chlorobenzene solution. Obtained polymers were precisely characterized by means of 1H NMR spectroscopy (Bruker Avance), Differential scanning calorimetry (TA Instruments Q 2000) and Gel permeation chromatography (Agilent Technologies 1100 series) methods. The microbial degradability of synthesized polymer sample having Mn = 12 kg/mol, Mw/Mn = 2.5 and crystallinity degree of 53 % was examined. The polymer in the form of melt-pressed films and powder form was bacterially aged in Bacillus subtilis (BS) strain inoculated mineral and nutrient media for 42 days. Scanning electron microscopy (SEM) and Confocal laser scanning microscopy (CLSM) confirmed the crack development on the surface of films as the consequence of microbial attack in comparison with unchanged control samples. Moreover, the pink coloration of polymer suspension was observed as the consequence of bacterial activity.

Diplomová práce se zabývá vlivem nutričních a aeračních faktorů na produkci lipáz bakterií Bacillus subtilis (CCM 1999). Produkce lipáz byla studována zejména z hlediska katalytického působení lipáz při degradaci polyesterových řetězců. Mezi studované parametry patřily: růst bakterií, lipolytická aktivita, pH optimum, teplotní optimum, tepelná stabilita, proteolytická aktivita, množství bílkovin, atd. a to v různých typech živných medií zaočkovaných Bacillus subtilis. Jedna série vzorků kultivačních médií pro BS na bázi: pepton a kvasničný extrakt (NB), pepton, kvasničný extrakt s 2% přídavkem (w/v) glukózy (NBG) a minerální médium s kvasničným extraktem (MS-YE) obsahovala jeden PCL vzorek o definovaných rozměrech (Mn = 10 kDa, = 1.4). Experimenty probíhaly po dobu 21 dnů pří rychlosti třepání 160 a 200 rpm. Přítomnost PCL způsobila v obou typech médií (NB, NBG) inokulovaných BS zvýšení lipolytické aktivity, což naznačuje, uvolnění a následné uplatnění se nízko-molekulekulárních řetězců PCL jako substrátů pro BS. BS kultivovaný v MS-YE medium vykazoval ve srovnání s NB a NBG médii nízké hodnoty lipolytické aktivity a to i v přítomnost PCL. Během experimentů se hodnota pH posunula z neutrální (pH 7.0) do alkalické (pH 8.5-9.3) oblasti a to ve všech typech médií s i bez přítomnosti PCL vzorku v důsledku metabolických pochodů BS využívajících různé substráty. Lipolytické enzymy stanovené v supernatanech bez bakteriálních buněk vykazují dvě pH optima v přítomnosti PCL, pH 7 a 9. V nepřítomnosti polymeru vykazují pouze jedno pH optimum při pH 7. Na základě měření tepelné stability bylo prokázáno, že extracelulární lipázy jsou relativně termostabilní enzymy, zejména v nepřítomnosti polymeru. Dále byla provedena základní proteomická analýza lipáz produkovaných bakterií Bacillus subtilis v NBG médiu pomocí metody peptidového mapování (PMF). Byla ověřena přítomnost proteinů s molární hmotnosti (19.3 kDa) pomocí FPLC. SDS-PAGE a IEF-PAGE prokázaly přítomnost těchto proteinů v obou studovaných mediích inokulovaných BS (NBG vs. NBG/PCL). Zásadní rozdíly proteinového složení v přítomnosti PCL nebyly potvrzeny a identifikace pomoci MALDI-TOF hmotnostní spektrometrie nestanovila žádnou lipázu. Proces degradace v PCL vzorcích byl vyhodnocen také na základě hmotnostních úbytků, které byly zjištěny ve všech typech médií inokulovaných BS pravděpodobně v důsledku synergického účinku enzymaticky-katalyzované a biotické hydrolýzy v alkalickém prostředí. . Modelová degradační studie PCL a jeho kompozitu s oxidem grafenu (2.7 hm.%, GO) byla provedena v přítomnosti bakterie Bacillus subtilis v NBG při 30 °C a počátečním pH 7 po dobu tří týdnů. Hmotností úbytky PCL filmů se postupně zvyšovaly během celého degradačního testu až ke 12 hm%. Degradace PLC/GO kompozitu probíhala pomaleji, což je prokázáno maximální hmotnostním úbytkem 5 hm%. Podobný charakter elučních křivek PCL a jeho kompozitu stanovený pomocí SEC potvrzoval snížení molární hmotnosti po degradaci.

Pharmaceuticals are micropollutants, that enter the environment mainly through Wastewater Treatment Plants (WWTPs). In this work microbial community has been studied in sediments of a stream, which is located near a WWTP. This sediment is contaminated with pharmaceuticals. The subject of this thesis was to determine the presence of pharmaceuticals and microbial community in this study site and to point out possible relationships between these factors. Twelve pharmaceuticals were identified at concentrations reaching levels of ng/g. The concentrations of the compounds form a gradient that decreases with the distance from WWTP. Microbial biomass was estimated using the analysis of phospholipid fatty acids and microbial community was described using next-generation DNA sequencing. The analysis of phospholipid fatty acids pointed out, that with the increasing distance from WWTP the amount of microbial biomass decreases. DNA sequencing revealed large microbial diversity in the studied sediment. For evaluation of the relationship between the microbial community and pharmaceuticals in the stream sediment, Principal Component Analysis (PCA) was used. The result of PCA showed, that in the stream sediment (depth 10-30 cm), Betaproteobacteria negatively correlated with triclosan and Clostridia negatively...

Introduction: Over the past few decades, nanoparticles (NPs) have gained immeasurable interest in the field of drug delivery. Various NP formulations have been disseminated in drug development in an attempt to increase efficacy, safety and tolerability of incorporated drugs. In this context, NP formulations that increase solubility, control release, and/or affect the in vivo disposition of drugs, were developed to improve the pharmacokinetic and pharmacodynamic properties of encapsulated drugs.Areas covered: In this article, important properties related to NP function such as particle size, surface charge and shape are disseminated. Also, the current understanding of how NP characteristics affect particle uptake and targeted delivery is elucidated. Selected NP systems currently used in delivery of drugs in biological systems and their production methods are discussed as well. Emphasis is placed on current NP formulations that are shown to reduce drug-induced adverse renal complications.Expert opinion: Formulation designs utilizing NP-encapsulated drugs offer alternative pharmacotherapy options with improved safety profiles for current and emerging drugs. NPs have been shown to increase the therapeutic index of several entrapped drugs mostly by decreasing drug localization and side effects on organs. Recent studies on NP-encapsulated chemotherapeutic and antibiotic medications show enhanced therapeutic outcomes by altering drug degradation, increasing systemic circulation and/or enhancing cell specific targeting. They may also reduce the distribution of encapsulated drugs into the kidneys and attenuate drug-associated adverse renal complications. The usefulness of NP formulation in reducing the nephrotoxicity of nonsteroidal anti-inflammatory drugs is an underexplored territory that deserves more attention.

L'irrigation par les eaux usées est une pratique intéressante dans les régions arides et semi-arides où la ressource en eau subit une pression accrue. Cependant, cette pratique risque de contaminer les sols par des contaminants chimiques tels que les polluants organiques émergents comme les médicaments. Les mécanismes de transfert et de transformation de ces molécules sont encore peu connus. L'objectif de cette thèse a été d'étudier les processus de biodégradation et de sorption des médicaments en conditions contrôlées, avec une réflexion dans le contexte de la réutilisation des eaux usées pour l'irrigation. Nous avons exploité la signature chirale de l'antidépresseur venlafaxine (VEN) et de son métabolite humain majeur O-desméthyl venlafaxine (ODV) afin de discriminer le processus biologique et les processus abiotiques. Les résultats au laboratoire ont montré une corrélation entre le taux de biodégradation et le changement de fraction énantiomérique. La fraction énantiomérique de la VEN a été ensuite suivie à la sortie d'une STEP et dans une rivière recevant ce rejet, où un changement de la fraction énantiomérique a été observé, montrant l'intérêt de mieux développer cette approche pour des études de biodégradation in situ. Le processus de sorption des molécules cationiques VEN et ODV a été étudié avec deux approches, statique en batch et dynamique en colonne de lixiviation, avec une comparaison avec les molécules neutres carbamazépine et son métabolite trans-10,11-dihydro-10,11-dihydroxy carbamazepine. L'étude en batch a montré que pH et force ionique a influencé la sorption des molécules cationiques mais pas celle des molécules neutres. L'échange cationique pourrait ainsi jouer un rôle important dans la sorption des molécules cationiques. L'étude de la lixiviation a montré que les molécules neutres ont été plus mobiles que les molécules cationiques et elles sont susceptibles de contaminer l'eau souterraine dans le cas de l'irrigation par des eaux usées. / Wastewater irrigation represents great interest in arid and semi-arid regions where water demand is important. However, wastewater irrigation results in, for example, soil contamination by emerging organic pollutants such as pharmaceuticals. Transport and transformation mechanisms of these substances are still poorly understood. The objective of this thesis was to study the processes of biodegradation and sorption of pharmaceutical products in laboratory experiments, with a special reflection in the context of wastewater irrigation. Firstly, we exploited the chiral signature of the antidepressant venlafaxine (VEN) and its major human metabolite O-desmethyl venlafaxine (ODV) in order to discriminate the biological processes from other processes. Laboratory experiment showed a correlation between the biodegradation rate and the change in enantiomer fraction. The VEN was then monitored at the outlet of a WWTP and in the river receiving the discharge. A change in enantiomer fraction showed the interest for a better development of this application to investigate in situ biodegradation. Secondly, the sorption of cationic molecules VEN and ODV, as well as the neutral molecules antiepileptic carbamazepine and its human metabolite trans-10,11-dihydro-10,11-dihydroxy carbamazepine, was studied in batch and soil column leaching experiments. The pH and ionic strength conditions in batch experiment influenced the sorption of VEN and ODV, while there was little impact for neutral compounds. The cationic exchange should play an important role in the sorption process of cationic molecules. Leaching study showed that neutral compounds are much more mobile than cationic compounds; therefore they may contaminate groundwater in the case of wastewater irrigation.

No description available.

The accumulation of industrial contaminants in the natural environments have rapidly become a serious threat for human and animal life. Fortunately, there are microorganisms capable of degrading or transforming environmental contaminants. The present dissertation work aimed to understand the genomic basis of microbial degradation and resistance. The focus was the genomic study of the following bacteria: a) Pseudomonas fluorescens NCIMB 11764, a unique bacterium with specific enzymes that allow cyanide adaptation features. Potential cyanide degradation mechanisms found in this strain included nit1C cluster, and CNO complex. Potential cyanide tolerance genes found included cyanide insensitive oxidases, nitric oxide producing gene, and iron metabolism genes. b) Cupriavidus sp. strain SK-3 and strain SK-4. The genome of both bacteria presented the bph operon for polychlorinated biphenyl (PCB) degradation, but we found differences in the sequences of the genes. Those differences might indicate their preferences for different PCB substrates. c) Arsenic resistant bacterial communities observed in the Atacama Desert. Specific bacteria were found to thrive depending on the arsenic concentration. Examples were Bacteroidetes and Spirochaetes phyla whose proportions increased in the river with high arsenic concentrations. Also, DNA repair and replication metabolic functions seem to be necessary for resistance to arsenic contaminated environments. Our research give us insights on how bacteria communities, not just individually, can adapt and become resistant to the contaminants. The present dissertation work showed specific genes and mechanisms for degradation and resistance of contaminants that could contribute to develop new bioremediation strategies.