Thesis (M.S.)--Pennsylvania State University, 2009. / Mode of access: World Wide Web. Thesis advisor: Richard C. Ready.

The pressing need for clean renewable energy sources has aroused worldwide research interest on the exploration of biofuels produced from lignocellulosic feedstock (e.g. forestry or agricultural residues and municipal wastes). The general absence of cost-effective method to overcome the recalcitrant nature of cellulosic biomass is the major challenge for the industrialization of this so-called second-generation biofuel. With the purpose to enhance our understanding of the fundamental mechanism of thermophilic microbial cellulose conversion process, we used culture-independent metagenomic analysis based on Next Generation Sequencing to explore the physiological ecology of thermophilic cellulolytic microbial community and more importantly to discover metabolic potentials. During the enrichment of thermophilic cellulolytic consortium, noticeable effects of co-substrate and pH was observed and subsequently investigated. Based on the community structure revealed by 16S rRNA gene sequencing at various pH values, we concluded that keeping pH higher than 6.0 was crucial to maintain effective cellulose conversion because the growth of Thermoanaerobacterium over other more efficient cellulolytic populations could be practically avoided. Given in mind that uncharacterized microbial populations may possess critical enzymatic components that are essential for the breakdown of cellulosic feedstock, gene-centric metagenomic pipeline was developed to discover genes that are functionally beneficial for thermophilic cellulose hydrolysis. Aside from that, metagenomic gene mining based on functional prediction using HMM (Hidden Markov Model) showed higher positive ratio in identifying novel carbohydrate-active genes than that of functional screening. Without cultivation, near complete genomes of the major thermophilic cellulose degraders were recovered from the metagenome by a gene binning pipeline combining tetranucleotide frequency based primary k-means clustering and subsequent scaffolding with paired-end relationship between two reads (sequences). Furthermore, by quantifying the transcriptional activities of various carbohydrate-active genes in the metatranscriptome of the enriched thermophilic cellulose-degrading consortium, we disclosed significance of enzymes of GH09 and GH48 which had been underestimated by previous metagenomic studies. Eventually, metagenomic survey of various sludge samples collected at specific operational conditions helped to confirm the metabolism potential of thermophilic sludge in cellulose up taking by possessing more enzymes of GH05 and GH04 families. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

This thesis describes the results of the analytical effort dealing with the products from the preliminary experimental runs using the Advanced Extruder Feeder Biomass Liquefaction Facility in the period from August 1985 to December 1986. Results of the analyses show that a low-oxygen crude wood oil could be produced over a wide range of temperatures, pressures, with or without carbon monoxide and with or without a sodium carbonate catalyst. The analytical procedures have been adapted to evaluate the crude wood oil by standard investigative procedures, including elemental analysis, nuclear magnetic resonance, infrared spectroscopy, gas chromatograph-mass spectrometry, and gas chromatography.

The aim of this study was to evaluate plant growth, grain yield and symbiotic N contribution by 32 cowpea genotypes, at Taung in South Africa. The data from a 2-year field study conducted in 2005 and 2006 showed that genotypes Fahari, Pan 311 and Glenda exhibited the highest dry matter yield and N contribution as they produced 2.9-, 2.7- and 3.5-fold more dry matter than cv. ITH98-46 and yielded 2.7-, 2.2- and 3.2-fold more N than cultivar ITH98-46 from IITA. Except for Benpila, all the 32 cowpea genotypes derived between 52.0 and 80.9% of their N nutrition from symbiotic fixation in 2005, with IT82D-889, Botswana White, IT93K-2045-29 and Ngonji exhibiting the highest %Ndfa values. The genotype Fahari showed the highest amount N-fixed (182 kg N-fixed/ha), followed by Pan 311, Glenda, TVu11424 and Mamlaka which contributed 160, 146, 130 and 125 kg N/ha, respectively. Genotypes Pan 311, Fahari and Glenda were among those that produced highest grain yield in 2005 and except for CH14 and IT86S-2246 (which produced 131 kg N/ha each), Fahari, Glenda and Pan 311, were again the highest in symbiotic N contribution (112, 106 and 105 kg N/ha, respectively). Grain yield was similarly high in Glenda, Pan 311 and Fahari (3.3, 3.1 and 2.9 t/ha, respectively) in 2006. In general, these data show that genotypes that fixed more N also produced more biomass and grain yield and are therefore, the best candidates for inclusion in cropping systems as biofertilizers.

No description available.

No description available.

No description available.

No description available.

The objective of this study was to evaluate the short-term (one-year) biomass production in red clover and to obtain an estimate of the heritability of this characteristic. Progenies from parents with high biomass had higher biomass than those from parents with low biomass or having one parent in each category. The narrow-sense heritability estimated from mid-parent offspring regression was 0.23, from parent-offspring correlation was 0.22, and realized heritability was 0.15, indicating that progeny testing would be required for successful selection of populations with greater biomass production. Plants selected for high biomass production tended to have higher shoot:root ratios and flower more profusely than the parental checks and the low biomass plants. This indicates that by selecting for high biomass, red clover will be selected for more annual growth habit at the same time.

The aim of this work was to develop methods of measuring pore size and the related surface area and pore volume, and then to apply these methods in studying the effects of degradation and lignification on these properties. Colloidal gold particles of prescribed sizes (2-10 nm in diameter) were used as molecular probes to determine pore size in maize and rape walls of different cell types. The particles were visualised by electron microscopy, and this indicated that the pore size in maize parenchyma walls was somewhere between 3 and 5 nm. Gas adsorption analysis provides information on pore size, surface area and pore volume, and was used to study cell walls of maize, alfalfa, wheat, timothy, and rape. This showed that the overall porous structure of the plants selected was very similar. The pore size distributions showed that the vast majority of pores had radii less than 3 nm, although wheat and timothy appeared to have a greater number of larger pores. The physical properties of plants containing type 1 walls were also investigated by this method. This illustrated how gas adsorption could be used to detect the changes in porosity and surface area which arise from the extraction of pectic polysaccharides. The effect of degradation on porosity was investigated using the same five plant types as had been studied previously. It was found that there was no great change in the porous structure as the walls were digested, except for wheat and timothy which both lost the larger pores they possessed before degradation. This resulted in pore size distributions more typical of the other three plant types. The data indicated that degradation occurred by a surface erosion process. Porosity and surface area did not alter greatly between cell walls of varying levels of lignification.