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Surface Treatment of Materials for BioTechnologies
Šupák, Marek ; Slámová, Jitka (referee) ; Krčma, František (advisor)
The theoretical part focuses on the importance of yeast, its role in brewing, the need for a reliable and economically beneficial pasteurization step that would meet modern requirements. Also in this part is defined plasma, its occurrence and the use of the glass structure used in the practical part. In the first part of the experimental work, the bachelor thesis deals with the action of plasma as a means of pasteurization. Saccharomyces cerevisiae yeast was introduced into the plasma. Gradually, the period of exposure of the yeast to the plasma discharge was determined and the number of survived and dead cells monitored. The methylene blue dye was used to identify yeast viability. After staining, the yeast was monitored under a microscope and calculated. Bürker's cell was used to determine the number of yeast cells. The experiment demonstrated plasma activity as a sterilization step, due to the decreasing number of living cells and the increase in the number of dead cells in the yeast-containing sample. In the 2nd part the surface was activated in the plasma discharge. The glass thus prepared was immersed in the culture medium for 24 hours to form a layer of culture medium on the surface of the glass. The remainders of the culture medium were then discharged and a small amount of yeast in the distilled water was pipetted. After 24 hours the yeast was counted on the Bürker's cell, the yeast growth was evaluated and the plasma activation efficiency was evaluated for activation and layer formation. The method of contact angles was used to confirm the effect of plasma on the surface of the glass. In this section, we demonstrated the effect of plasma on the surface of the glass and the formation of a thin layer of nutrient medium that supplied the yeast with the necessary substances for reproduction.
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Plasma Sterilization of Biopolymers
Hantáková, Michaela ; Slámová, Jitka (referee) ; Krčma, František (advisor)
This thesis is dialled to studying the plasma sterilization of biopolymers using lowtemperature non-equilibrium plasma of electrical discharges for the medical applications. The dielectric barrier discharge was generated in atmospheric gases based mixtures at atmospheric pressure. The sodium glass plates were used as dielectric to ensure the discharge operation in the atmospheric pressure glow mode. The effect of various physical parameters of the plasma as well as the stress factors on the sterilization efficiency were studied. The gram-positive bacteria Micrococcus Luteus and gram-negative bacteria Serratia Marcesceus were used as the model organisms under the current study. The bacterial samples were deposited on the Whatman 1 paper as well as on the biopolymer fibres made of P3HB (trade mark Hydal of company Nafigate Corporation). and then exposed to the plasma. The experimental results are evaluated by the available microbiological analysis methods. The samples were after exposed directly to the plasma. Experimental results were evaluated by the accessible microbiologic techniques. The results confirmed the plasma sterilization success; the best results were obtained using sterilization by DBD generated in wet air enriched by oxygen. The detailed research of sterilization using the low temperature non-equilibrium plasma will be a subject of consequent master Thesis.
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Study of Sterilization Effects Initiated by Dielectric Barriere Discharge
Slámová, Jitka ; Pekárek, Stanislav (referee) ; doc. RNDr. Karol Hensel, Ph.D., oponent (referee) ; Krčma, František (advisor)
The overall goal of the presented dissertation thesis was to study the sterilization efficiency of dielectric barrier discharge operated at atmospheric pressure. The fungi Aspergillus niger, gram-positive bacteria Bacillus subtilis and in some experiments also gram-negative bacteria Escherichia coli were used as a bio-indicator enabling to evaluate the effect of plasma assisted microbial inactivation. The samples of microorganism were placed on paper Whatman 1 or PET foil and exposed to plasma. The plasma was generated in argon, nitrogen, synthetic dry/humid air with frequency up to 10 kHz and plasma power density in the range of 1,2-2,9 W/cm3 (according to the process gas). The influence of process gas, plasma power density, plasma exposition time, type of microorganism and material of the substrate on the sterilization effect of dielectric barrier discharge was evaluated. Furthermore the contribution of each single mechanism (UV radiation, temperature and reactive species) to the sterilization effect of plasma and influence of gas humidity was evaluated. The DBD was analysed by means of optical emission spectroscopy, thermocouple was used to measure temperature during a sterilization process. In order to verify the mechanical damage of the microbial cell or the substrates during the plasma process the samples were studied by scanning electron microscopy. Generally, on the basis of experimental results, at increasing treatment times, the remaining number of spores (CFU) decreased. Similarly at increasing the plasma power input, the sterilization rate increased. When sterilising the spores of A. niger in plasma using different process gasses, the efficiency of plasma sterilization decreased as follows: argon, humid synthetic air, nitrogen and dry synthetic air. The results observed in argon plasma using different microorganism demonstrated that the sensitivity of vegetative cells resp. spores to DBD decreased as follows: A. niger spores, B. subtilis vegetative cells, E. coli vegetative cells and B. subtilis spores. Simultaneously results observed for sterilization of spores and vegetative cells of B. subtilis and A. niger demonstrated that the spores are generally more resistant to plasma than are the corresponding vegetative cells. Combining the results of contribution of each single mechanism, optical emission spectroscopy and inactivation characteristic it was found out that the reactive species significantly contribute to the plasma sterilization in all process gasses. Furthermore the inactivation process can be partly assisted by UV radiation and also the temperature can contribute in limited extent to inactivation process in some gasses. The contribution of UV radiation to the plasma sterilization decreased as follows: nitrogen, argon, dry syntetic air and humid syntetic air. Moreover it was found out that the contribution of each single mechanism can be species dependent, this is due to the different response of microorganism to the unfavorable external conditions. SEM analysis of the substrates prooved the etching actions of the plasma generated in all process gasses on the surface of the PET foil. The several minute plasma exposition of the PET foil resulted in the occurence of the „hole corrosion“ on the PET surface. Contrary to these there were no visible changes observed in the paper structure.
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Study of sterilization effect of diaphragm discharge in liquids
Holíková, Lenka ; Slámová, Jitka (referee) ; Kozáková, Zdenka (advisor)
The main objective of this thesis is to study the sterilizing effect of diaphragm discharge in liquids. Sterilization is a process, which can eliminate all forms of life. Generally, sterilization is divided into physical and chemical methods. Plasma sterilization is ranked among physical methods although the action of chemical processes participates in the decontamination as well. Effects of UV radiation, free radicals and temperature are utilized in these methods. Fungi spores of Aspergillus niger F8189 and bacteria spores of Bacillus subtilis are selected as model organisms. Aspergillus niger microorganism is suitable for its resistance to changes in pH and it is viable in a wide range of pH values. Bacillus subtilis is chosen because of a good heat resistance. Diaphragm discharge is one of the possible types of electrical discharges in generated liquids. It is a low-temperature plasma, which is generated using a high DC voltage. In the created plasma streamers various physical and chemical processes rise. The chemical processes are mainly the generation of active species and particles that initiate subsequent chemical reactions and attack mould spores and bacteria in liquids. The physical processes include shock waves, strong electric field and ultraviolet radiation. Experiments were conducted in a reactor with separate cathode and anode space. In the dielectric barrier PET diaphragm with a pin-hole (initial diameter of 0.4 mm) was attached. Enlargement of the hole was observed as a result of degradation of material at the edge of holes due to the discharge. Degradation of spores was observed, depending on the time and on the input power. Other parameters measured were pH, conductivity and temperature. Experiments did not show any difference of discharge activity in the cathode and anode area. The main factor in the removal of spores Aspergillus niger was probably the temperature because no demonstrable effect of sterilization by the diaphragm discharge operation had been observed when heat resistant Bacillus subtilis was used. Also, it was made an attempt, which has been studied only the temperature effect of the fungi spores of Aspergillus niger. The samples were placed in a thermoregulator, where it was simulated the same temperature increase as at the discharge. The experiment had a similar course as an attempt at the discharge.
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Surface Treatment of Materials for BioTechnologies
Šupák, Marek ; Slámová, Jitka (referee) ; Krčma, František (advisor)
The theoretical part focuses on the importance of yeast, its role in brewing, the need for a reliable and economically beneficial pasteurization step that would meet modern requirements. Also in this part is defined plasma, its occurrence and the use of the glass structure used in the practical part. In the first part of the experimental work, the bachelor thesis deals with the action of plasma as a means of pasteurization. Saccharomyces cerevisiae yeast was introduced into the plasma. Gradually, the period of exposure of the yeast to the plasma discharge was determined and the number of survived and dead cells monitored. The methylene blue dye was used to identify yeast viability. After staining, the yeast was monitored under a microscope and calculated. Bürker's cell was used to determine the number of yeast cells. The experiment demonstrated plasma activity as a sterilization step, due to the decreasing number of living cells and the increase in the number of dead cells in the yeast-containing sample. In the 2nd part the surface was activated in the plasma discharge. The glass thus prepared was immersed in the culture medium for 24 hours to form a layer of culture medium on the surface of the glass. The remainders of the culture medium were then discharged and a small amount of yeast in the distilled water was pipetted. After 24 hours the yeast was counted on the Bürker's cell, the yeast growth was evaluated and the plasma activation efficiency was evaluated for activation and layer formation. The method of contact angles was used to confirm the effect of plasma on the surface of the glass. In this section, we demonstrated the effect of plasma on the surface of the glass and the formation of a thin layer of nutrient medium that supplied the yeast with the necessary substances for reproduction.
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Plasma Sterilization of Biopolymers
Hantáková, Michaela ; Slámová, Jitka (referee) ; Krčma, František (advisor)
This thesis is dialled to studying the plasma sterilization of biopolymers using lowtemperature non-equilibrium plasma of electrical discharges for the medical applications. The dielectric barrier discharge was generated in atmospheric gases based mixtures at atmospheric pressure. The sodium glass plates were used as dielectric to ensure the discharge operation in the atmospheric pressure glow mode. The effect of various physical parameters of the plasma as well as the stress factors on the sterilization efficiency were studied. The gram-positive bacteria Micrococcus Luteus and gram-negative bacteria Serratia Marcesceus were used as the model organisms under the current study. The bacterial samples were deposited on the Whatman 1 paper as well as on the biopolymer fibres made of P3HB (trade mark Hydal of company Nafigate Corporation). and then exposed to the plasma. The experimental results are evaluated by the available microbiological analysis methods. The samples were after exposed directly to the plasma. Experimental results were evaluated by the accessible microbiologic techniques. The results confirmed the plasma sterilization success; the best results were obtained using sterilization by DBD generated in wet air enriched by oxygen. The detailed research of sterilization using the low temperature non-equilibrium plasma will be a subject of consequent master Thesis.
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Study of Sterilization Effects Initiated by Dielectric Barriere Discharge
Slámová, Jitka ; Pekárek, Stanislav (referee) ; doc. RNDr. Karol Hensel, Ph.D., oponent (referee) ; Krčma, František (advisor)
The overall goal of the presented dissertation thesis was to study the sterilization efficiency of dielectric barrier discharge operated at atmospheric pressure. The fungi Aspergillus niger, gram-positive bacteria Bacillus subtilis and in some experiments also gram-negative bacteria Escherichia coli were used as a bio-indicator enabling to evaluate the effect of plasma assisted microbial inactivation. The samples of microorganism were placed on paper Whatman 1 or PET foil and exposed to plasma. The plasma was generated in argon, nitrogen, synthetic dry/humid air with frequency up to 10 kHz and plasma power density in the range of 1,2-2,9 W/cm3 (according to the process gas). The influence of process gas, plasma power density, plasma exposition time, type of microorganism and material of the substrate on the sterilization effect of dielectric barrier discharge was evaluated. Furthermore the contribution of each single mechanism (UV radiation, temperature and reactive species) to the sterilization effect of plasma and influence of gas humidity was evaluated. The DBD was analysed by means of optical emission spectroscopy, thermocouple was used to measure temperature during a sterilization process. In order to verify the mechanical damage of the microbial cell or the substrates during the plasma process the samples were studied by scanning electron microscopy. Generally, on the basis of experimental results, at increasing treatment times, the remaining number of spores (CFU) decreased. Similarly at increasing the plasma power input, the sterilization rate increased. When sterilising the spores of A. niger in plasma using different process gasses, the efficiency of plasma sterilization decreased as follows: argon, humid synthetic air, nitrogen and dry synthetic air. The results observed in argon plasma using different microorganism demonstrated that the sensitivity of vegetative cells resp. spores to DBD decreased as follows: A. niger spores, B. subtilis vegetative cells, E. coli vegetative cells and B. subtilis spores. Simultaneously results observed for sterilization of spores and vegetative cells of B. subtilis and A. niger demonstrated that the spores are generally more resistant to plasma than are the corresponding vegetative cells. Combining the results of contribution of each single mechanism, optical emission spectroscopy and inactivation characteristic it was found out that the reactive species significantly contribute to the plasma sterilization in all process gasses. Furthermore the inactivation process can be partly assisted by UV radiation and also the temperature can contribute in limited extent to inactivation process in some gasses. The contribution of UV radiation to the plasma sterilization decreased as follows: nitrogen, argon, dry syntetic air and humid syntetic air. Moreover it was found out that the contribution of each single mechanism can be species dependent, this is due to the different response of microorganism to the unfavorable external conditions. SEM analysis of the substrates prooved the etching actions of the plasma generated in all process gasses on the surface of the PET foil. The several minute plasma exposition of the PET foil resulted in the occurence of the „hole corrosion“ on the PET surface. Contrary to these there were no visible changes observed in the paper structure.
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Study of sterilization effect of diaphragm discharge in liquids
Holíková, Lenka ; Slámová, Jitka (referee) ; Kozáková, Zdenka (advisor)
The main objective of this thesis is to study the sterilizing effect of diaphragm discharge in liquids. Sterilization is a process, which can eliminate all forms of life. Generally, sterilization is divided into physical and chemical methods. Plasma sterilization is ranked among physical methods although the action of chemical processes participates in the decontamination as well. Effects of UV radiation, free radicals and temperature are utilized in these methods. Fungi spores of Aspergillus niger F8189 and bacteria spores of Bacillus subtilis are selected as model organisms. Aspergillus niger microorganism is suitable for its resistance to changes in pH and it is viable in a wide range of pH values. Bacillus subtilis is chosen because of a good heat resistance. Diaphragm discharge is one of the possible types of electrical discharges in generated liquids. It is a low-temperature plasma, which is generated using a high DC voltage. In the created plasma streamers various physical and chemical processes rise. The chemical processes are mainly the generation of active species and particles that initiate subsequent chemical reactions and attack mould spores and bacteria in liquids. The physical processes include shock waves, strong electric field and ultraviolet radiation. Experiments were conducted in a reactor with separate cathode and anode space. In the dielectric barrier PET diaphragm with a pin-hole (initial diameter of 0.4 mm) was attached. Enlargement of the hole was observed as a result of degradation of material at the edge of holes due to the discharge. Degradation of spores was observed, depending on the time and on the input power. Other parameters measured were pH, conductivity and temperature. Experiments did not show any difference of discharge activity in the cathode and anode area. The main factor in the removal of spores Aspergillus niger was probably the temperature because no demonstrable effect of sterilization by the diaphragm discharge operation had been observed when heat resistant Bacillus subtilis was used. Also, it was made an attempt, which has been studied only the temperature effect of the fungi spores of Aspergillus niger. The samples were placed in a thermoregulator, where it was simulated the same temperature increase as at the discharge. The experiment had a similar course as an attempt at the discharge.
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