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Role of extracellular DNA in microbial biofilms
Gromov, Anton ; Chytilová, Aneta (referee) ; Obruča, Stanislav (advisor)
Abstract This bachelor’s thesis deals with defining the role of extracellular DNA in microbial biofilms. The thesis includes a part about the basic characteristics and functions of biofilms, as well as the characteristics and functions of extracellular DNA. The theoretic part additionally deals with the process of formation of biofilms, and the influence of different types of stresses on it. Also, the paper discusses the role of such stresses. The role of biofilm in bacteria and their reproduction methods are also discussed. An interesting section of the thesis outlines the impact of antibiotics on biofilms, or the ways to gain DNA or use DNase. The eDNA functions and their effects on bacterial defence will be discussed thoroughly. In the experimental part, the biofilm content was examined and compared with cells growing in a liquid and solid medium. Measurement of DNA content in media was carried out and the effects of salt and temperature stresses on biofilm were also measured. Stress conditions affected the production of PHB, which is used as a reserve form of energy and carbon. Total sugars were measured using an anthracite reagent to study the effects of stresses on the content of macromolecules. The presence of eDNA in biofilms and planktonic cells was firstly checked using gel electrophoresis and then accurate concentrations in planktonic and biofilm cells were determined using different spectrophotometric methods.
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Molecular organization of humic acids in solutions
Chytilová, Aneta ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
The diverse structure and content of the highly varied functional groups of humic acids determine these substances as a worthwhile study material for a number of scientific institutions. Above all, the structure causes a wide range of their interesting properties, especially spectral, colloidal, electrochemical, ion-exchange and adsorption properties. Humic acids have variety of utilization in the industry while they have been the subject of a range of further research and development. The character of these complex heterogeneous polydisperse substances is mainly cyclic and aromatic, which according to some studies results in their brown color. Generally, there are multiple theories assuming their potential secondary structure. The aim of this study is the analysis of structure and conformation of humic acids in aqueous solutions. For the purposes mentioned above a concentration series of humic acids have been prepared in four different mediums: 0,1 M NaOH, humic acids in water with pH modified to 12 (basic medium), 0,1 M NaOH + 0,1 M HCl, 0,1 M NaCl (neutral medium). In order to study conformations several analytic methods have been used: ultraviolet and visible spectroscopy, dynamic light scattering, electrophoretic light scattering, potentiometric determination of pH and direct conductimetry. Throughout the experimentation the emphasis was mainly on the purity of humic acids extracted from lignite.
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Fractionation and molecular organization of humic acids
Chytilová, Aneta ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
Humic acids are part of the natural organic matter occurring all around us. The aim of this thesis is to study the molecular organization, conformation of humic acids in aqueous solutions, that always raise a number of questions. For a long time, the scientists all over the world argue, if humic acid are polymers, micelles or supramolecules. Over time, thanks to new technologies, their opinions are moving away from a polymer model and tend rather to supramolecular arrangement of humic acids. Studying humic complex systems is not easy, because they are polydisperse and heterogeneous, which significantly complicates any characterization. Moreover, its molecular organization is affected by many factors such as e.g. pH, ionic strength and etc. For the study of the conformation of humic acids, concentration series of IHSS (International humic substances asociation) Leonardite humic acids stamdards in four different mediums were prepared: 0,1 M NaOH, humic acids in water with pH modified to 12 (basic medium), 0,1 M NaOH + 0,1 M HCl, 0,1 M NaCl (neutral environment). Furthermore it has been performed the fractionation of humic acids for the purpose of simplifying the complicated structure. Prepared concentration series were characterized with several analytical methods such as ultraviolet and visible spectroscopy, dynamic light scattering, electrophoretic light scattering, microrheology, gel permeation chromatography, potentiometric pH determination and direct conductometry. Diploma thesis is built on the previous bachelor thesis in which different sample of humic acids was studied. The measured results indicate that the studied systems show supramolecular behavior and in some cases are subject to aggregation into larger units (micelles).
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Role of extracellular DNA in microbial biofilms
Gromov, Anton ; Chytilová, Aneta (referee) ; Obruča, Stanislav (advisor)
Abstract This bachelor’s thesis deals with defining the role of extracellular DNA in microbial biofilms. The thesis includes a part about the basic characteristics and functions of biofilms, as well as the characteristics and functions of extracellular DNA. The theoretic part additionally deals with the process of formation of biofilms, and the influence of different types of stresses on it. Also, the paper discusses the role of such stresses. The role of biofilm in bacteria and their reproduction methods are also discussed. An interesting section of the thesis outlines the impact of antibiotics on biofilms, or the ways to gain DNA or use DNase. The eDNA functions and their effects on bacterial defence will be discussed thoroughly. In the experimental part, the biofilm content was examined and compared with cells growing in a liquid and solid medium. Measurement of DNA content in media was carried out and the effects of salt and temperature stresses on biofilm were also measured. Stress conditions affected the production of PHB, which is used as a reserve form of energy and carbon. Total sugars were measured using an anthracite reagent to study the effects of stresses on the content of macromolecules. The presence of eDNA in biofilms and planktonic cells was firstly checked using gel electrophoresis and then accurate concentrations in planktonic and biofilm cells were determined using different spectrophotometric methods.
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Fractionation and molecular organization of humic acids
Chytilová, Aneta ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
Humic acids are part of the natural organic matter occurring all around us. The aim of this thesis is to study the molecular organization, conformation of humic acids in aqueous solutions, that always raise a number of questions. For a long time, the scientists all over the world argue, if humic acid are polymers, micelles or supramolecules. Over time, thanks to new technologies, their opinions are moving away from a polymer model and tend rather to supramolecular arrangement of humic acids. Studying humic complex systems is not easy, because they are polydisperse and heterogeneous, which significantly complicates any characterization. Moreover, its molecular organization is affected by many factors such as e.g. pH, ionic strength and etc. For the study of the conformation of humic acids, concentration series of IHSS (International humic substances asociation) Leonardite humic acids stamdards in four different mediums were prepared: 0,1 M NaOH, humic acids in water with pH modified to 12 (basic medium), 0,1 M NaOH + 0,1 M HCl, 0,1 M NaCl (neutral environment). Furthermore it has been performed the fractionation of humic acids for the purpose of simplifying the complicated structure. Prepared concentration series were characterized with several analytical methods such as ultraviolet and visible spectroscopy, dynamic light scattering, electrophoretic light scattering, microrheology, gel permeation chromatography, potentiometric pH determination and direct conductometry. Diploma thesis is built on the previous bachelor thesis in which different sample of humic acids was studied. The measured results indicate that the studied systems show supramolecular behavior and in some cases are subject to aggregation into larger units (micelles).
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|
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Molecular organization of humic acids in solutions
Chytilová, Aneta ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
The diverse structure and content of the highly varied functional groups of humic acids determine these substances as a worthwhile study material for a number of scientific institutions. Above all, the structure causes a wide range of their interesting properties, especially spectral, colloidal, electrochemical, ion-exchange and adsorption properties. Humic acids have variety of utilization in the industry while they have been the subject of a range of further research and development. The character of these complex heterogeneous polydisperse substances is mainly cyclic and aromatic, which according to some studies results in their brown color. Generally, there are multiple theories assuming their potential secondary structure. The aim of this study is the analysis of structure and conformation of humic acids in aqueous solutions. For the purposes mentioned above a concentration series of humic acids have been prepared in four different mediums: 0,1 M NaOH, humic acids in water with pH modified to 12 (basic medium), 0,1 M NaOH + 0,1 M HCl, 0,1 M NaCl (neutral medium). In order to study conformations several analytic methods have been used: ultraviolet and visible spectroscopy, dynamic light scattering, electrophoretic light scattering, potentiometric determination of pH and direct conductimetry. Throughout the experimentation the emphasis was mainly on the purity of humic acids extracted from lignite.
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