| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 102 === Cellulose is the most abundant polymer material on Earth. Certain microorganisms can produce cellulolytic enzymes and degrade cellulose efficiently. Cellulose is hydrolyzed and turns into glucose with the help of cellulase. Glucose derived from cellulose is fermented into ethanol, hydrogen and other volatile fatty acids. The fermentation products could provide a partial substitution for fossil fuels and other energy. If such abundant cellulose material can be used properly for the development of renewable biomass, it can not only ease the current problem of fossil fuel shortage, but also reduce the environmental pollution.
Cellulose is an organic polysaccharide and cannot be degraded easily. The objectives of this study were to enhance the efficiency of cellulose hydrolysis through the enrichment of rat cecal microbiota and fecal microbiota. By changing the medium composition, carbon sources and enrichment condition, the study tried to find out the best way to enrich the cellulolytic bacteria. The results showed that the best degradation efficiency happened in the beginning of the enrichment of rat cecal microbiota, cow fecal and rat fecal microbiota through activation and preculture. The best degradation efficiency of cow fecal microbiota is 75.5%, rat fecal microbiota is 62.6%, and rat cecal microbiota is 60.1%.
In order to make sure the presence of cellulolytic microorganism, functional-gene-specific primers were used to detect cellulase functional genes. According to NCBI database, the sequence result was Clostridium sp. Strain BNL1100. Clostridium is known as cellulolytic bacteria, thus the result indicated the existence of cellulolytic microorganisms in the enrichment. By detecting cellulase functional genes, the existence of cellulolytic microorganisms could also be inferred.
In order to find the suitable enrichment condition for the rat cecal microbiota and the cow fecal microbiota, different temperatures and pH values were used to evaluate the degradation efficiency. It turned out that the most suitable pH value for the rat cecal reactor and the cow fecal reactor is 6.5 and 7.5. Degradation didn’t report high efficiency at pH 7. The most suitable temperature was at 35C° to 40°C. The operating condition of reactor could be adjusted to the most suitable condition for the cellulolytic microorganism based on the tested pH value and temperature.
|
|---|
