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Composting of biodegradable polymers
Hollá, Tereza ; Smilek, Jiří (oponent) ; Obruča, Stanislav (vedoucí práce)
This master’s thesis deals with the study of composting of polyhydroxybutyrate (PHB) and polylactic acid (PLA). The experimental part focuses on the composting test based on the IS/ISO 20200 standard, in which biopolymers were degraded within 8 weeks. The advantage of the composting test was the unique use of bags for polymer granules, which simplified the handling of samples. The placement of the polymers ensured an even load of compost, which simulated the landfill environment, which also made this experiment exceptional. The use of different methods of analysis ensured the investigation of the influence of compost on the degradation of polymers, but also the influence of polymers on the compost microbiome. In the compost environment all of the studied polymers degraded. After 8 weeks the weight loss of approximately 40 % was detected in PHB. Amorphous PLA degraded completely in the 5th week of experiment, while semicrystalline PLA lost approximately 70 % of its weight in 8 weeks. Using SEM images and SEC analysis, we conclude that PHB degradation was predominantly biological. Degradation of PLA samples was found to be predominantly abiotic. Analysis of compost samples revealed that the enzymatic activity of esterases increased in composts with polymers compared to compost without polymers. The effect of polymers on the microbiome in compost was analyzed using Biolog EcoPlates™. Compost with PHB showed a high ability to adapt to various substrates and microbiome expanded during composting. In the case of a sample with semicrystalline PLA, it was found that in the last week of composting, the ability of microorganisms to adapt and use substrates decreased, which indicates a possible negative effect of this polymer on compost development.
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Thermophillic producers of PHA
Hollá, Tereza ; Müllerová, Lucie (oponent) ; Obruča, Stanislav (vedoucí práce)
This bachelor’s thesis deals with production of polyhydroxyalkanoates (PHA) by bacterial strain Chelatococcus thermostellatus. Polyhydroxyalkanoates are natural biopolymers produced by microorganisms. Microorganisms use them to store energy and carbon under stress conditions. In experimental part of this work the most appropriate conditions for growth of biomass and polyhydroxyalkanoates accumulation were detected. The capability of copolymer P(3HB-co-3HV) production by bacterial strain was also studied. Glucose was determined as the most appropriate carbon source for biomass growth and P(3HB) production. Content of P(3HB) in biomass was 59,42 % per cell weight. The accumulation of the copolymer by bacterial strain was detected, but at very low concentrations.
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Composting of biodegradable polymers
Hollá, Tereza ; Smilek, Jiří (oponent) ; Obruča, Stanislav (vedoucí práce)
This master’s thesis deals with the study of composting of polyhydroxybutyrate (PHB) and polylactic acid (PLA). The experimental part focuses on the composting test based on the IS/ISO 20200 standard, in which biopolymers were degraded within 8 weeks. The advantage of the composting test was the unique use of bags for polymer granules, which simplified the handling of samples. The placement of the polymers ensured an even load of compost, which simulated the landfill environment, which also made this experiment exceptional. The use of different methods of analysis ensured the investigation of the influence of compost on the degradation of polymers, but also the influence of polymers on the compost microbiome. In the compost environment all of the studied polymers degraded. After 8 weeks the weight loss of approximately 40 % was detected in PHB. Amorphous PLA degraded completely in the 5th week of experiment, while semicrystalline PLA lost approximately 70 % of its weight in 8 weeks. Using SEM images and SEC analysis, we conclude that PHB degradation was predominantly biological. Degradation of PLA samples was found to be predominantly abiotic. Analysis of compost samples revealed that the enzymatic activity of esterases increased in composts with polymers compared to compost without polymers. The effect of polymers on the microbiome in compost was analyzed using Biolog EcoPlates™. Compost with PHB showed a high ability to adapt to various substrates and microbiome expanded during composting. In the case of a sample with semicrystalline PLA, it was found that in the last week of composting, the ability of microorganisms to adapt and use substrates decreased, which indicates a possible negative effect of this polymer on compost development.
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Thermophillic producers of PHA
Hollá, Tereza ; Müllerová, Lucie (oponent) ; Obruča, Stanislav (vedoucí práce)
This bachelor’s thesis deals with production of polyhydroxyalkanoates (PHA) by bacterial strain Chelatococcus thermostellatus. Polyhydroxyalkanoates are natural biopolymers produced by microorganisms. Microorganisms use them to store energy and carbon under stress conditions. In experimental part of this work the most appropriate conditions for growth of biomass and polyhydroxyalkanoates accumulation were detected. The capability of copolymer P(3HB-co-3HV) production by bacterial strain was also studied. Glucose was determined as the most appropriate carbon source for biomass growth and P(3HB) production. Content of P(3HB) in biomass was 59,42 % per cell weight. The accumulation of the copolymer by bacterial strain was detected, but at very low concentrations.
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