Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Not available / text

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Stanley Roux. Vita. Includes bibliographical references.

Water is considered the most vital resource on earth and its quality is deteriorating. Not all residents living in South Africa‘s rural areas have access to treated drinking water, and use water from rivers, dams, and wells. The quality of these resources is unknown, as well as the effects of the bacteria in the water on human health. The heterotrophic plate count (HPC) method is a globally used test to evaluate microbial water quality. According to South African water quality guidelines, water of good quality may not contain more than a 1 000 coliforming units (CFU)/mℓ. There is mounting evidence that HPC bacteria may be hazardous to humans with compromised, underdeveloped, and weakened immune systems. In this study the pathogenic potential of HPC bacteria was investigated. Samples were collected from boreholes in the North West Province and HPCs were enumerated with a culture-based method. Standard physico-chemical parameters were measured for the water. Different HPC bacteria were isolated and purified and tested for α- or β-haemolysis, as well as the production of extracellular enzymes such as DNase, proteinase, lecithinase, chondroitinase, hyaluronidase and lipase, as these are pathogenic characteristics. The isolates were identified with 16S rRNA gene sequencing. The model for the human intestine, Hutu-80 cells, were exposed to the potentially pathogenic HPC isolates to determine their effects on the viability of the human cells. The isolates were also exposed to different dilutions of simulated gastric fluid (SGF) to evaluate its effect on the viability of bacteria. Antibiotic resistant potential of each isolate was determined by the Kirby-Bauer disk diffusion method. Three borehole samples did not comply with the physico-chemical guidelines. Half of the samples exceeded the microbial water quality guideline and the greatest CFU was 292 350 CFU/mℓ. 27% of the isolate HPC bacteria were α- or β- haemolytic. Subsequent analysis revealed the production of: DNase in 72%, proteinase in 40%, lipase and lecithinase in 29%, hyaluronidase in 25% and least produced was chondroitinase in 25%. The HPC isolates identified included: Alcaligenes faecalis, Aeromonas hydrophila and A. taiwanesis, Bacillus sp., Bacillus thuringiensis, Bacillus subtilis, Bacillus pumilus, Brevibacillus sp., Bacillus cereus and Pseudomonas sp. All the isolates, except Alcaligenes faecalis, were toxic to the human intestinal cells to varying degrees. Seven isolates survived exposure to the most diluted SGF and of these, four isolates also survived the intermediate dilution but, only one survived the highest SGF concentration. Some isolates were resistant to selected antibiotics, but none to neomycin and vancomycin. Amoxillin and oxytetracycline were the least effective of the antibiotics tested. A pathogen score was calculated for each isolate based on the results of this study. Bacillus cereus had the highest pathogen index with declining pathogenicity as follows: Alcaligenes faecalis > B. thuringiensis > Bacillus pumilus > Pseudomonas sp. > Brevibacillus > Aeromonas taiwanesis > Aeromonas hydrophila > Bacillus subtilis > Bacillus sp. The results of this study prove that standard water quality tests such as the physico-chemical and the HPC methods are insufficient to provide protection against the effects of certain pathogenic HPC bacteria. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Water is considered the most vital resource on earth and its quality is deteriorating. Not all residents living in South Africa‘s rural areas have access to treated drinking water, and use water from rivers, dams, and wells. The quality of these resources is unknown, as well as the effects of the bacteria in the water on human health. The heterotrophic plate count (HPC) method is a globally used test to evaluate microbial water quality. According to South African water quality guidelines, water of good quality may not contain more than a 1 000 coliforming units (CFU)/mℓ. There is mounting evidence that HPC bacteria may be hazardous to humans with compromised, underdeveloped, and weakened immune systems. In this study the pathogenic potential of HPC bacteria was investigated. Samples were collected from boreholes in the North West Province and HPCs were enumerated with a culture-based method. Standard physico-chemical parameters were measured for the water. Different HPC bacteria were isolated and purified and tested for α- or β-haemolysis, as well as the production of extracellular enzymes such as DNase, proteinase, lecithinase, chondroitinase, hyaluronidase and lipase, as these are pathogenic characteristics. The isolates were identified with 16S rRNA gene sequencing. The model for the human intestine, Hutu-80 cells, were exposed to the potentially pathogenic HPC isolates to determine their effects on the viability of the human cells. The isolates were also exposed to different dilutions of simulated gastric fluid (SGF) to evaluate its effect on the viability of bacteria. Antibiotic resistant potential of each isolate was determined by the Kirby-Bauer disk diffusion method. Three borehole samples did not comply with the physico-chemical guidelines. Half of the samples exceeded the microbial water quality guideline and the greatest CFU was 292 350 CFU/mℓ. 27% of the isolate HPC bacteria were α- or β- haemolytic. Subsequent analysis revealed the production of: DNase in 72%, proteinase in 40%, lipase and lecithinase in 29%, hyaluronidase in 25% and least produced was chondroitinase in 25%. The HPC isolates identified included: Alcaligenes faecalis, Aeromonas hydrophila and A. taiwanesis, Bacillus sp., Bacillus thuringiensis, Bacillus subtilis, Bacillus pumilus, Brevibacillus sp., Bacillus cereus and Pseudomonas sp. All the isolates, except Alcaligenes faecalis, were toxic to the human intestinal cells to varying degrees. Seven isolates survived exposure to the most diluted SGF and of these, four isolates also survived the intermediate dilution but, only one survived the highest SGF concentration. Some isolates were resistant to selected antibiotics, but none to neomycin and vancomycin. Amoxillin and oxytetracycline were the least effective of the antibiotics tested. A pathogen score was calculated for each isolate based on the results of this study. Bacillus cereus had the highest pathogen index with declining pathogenicity as follows: Alcaligenes faecalis > B. thuringiensis > Bacillus pumilus > Pseudomonas sp. > Brevibacillus > Aeromonas taiwanesis > Aeromonas hydrophila > Bacillus subtilis > Bacillus sp. The results of this study prove that standard water quality tests such as the physico-chemical and the HPC methods are insufficient to provide protection against the effects of certain pathogenic HPC bacteria. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Cai Yi Jin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 118-128). / Chapter 1. --- Introduction / Chapter 1.1 --- Importance and Cultivation history of edible mushroom --- p.1 / Chapter 1.2 --- Variety and structure of growth substrates for mushroom --- p.4 / Chapter 1.3 --- Mushroom growth and substrate-degrading enzymes --- p.8 / Chapter 1.4 --- Purpose of study --- p.15 / Chapter 2. --- Methods and Materials / Chapter 2.1 --- Organisms --- p.17 / Chapter 2.2 --- Media --- p.17 / Chapter 2.3 --- Culture conditions --- p.21 / Chapter 2.3.1 --- Growth temperature --- p.21 / Chapter 2.3.2 --- Growth Studies --- p.21 / Chapter 2.3.2.1 --- Effect of pH on mycelial growth --- p.21 / Chapter 2.3.2.2 --- Effect of different carbon sources on mycelial growth --- p.21 / Chapter 2.3.2.3 --- Effect of lignin-related phenolic monomers and tannin derivatives on fungal growth --- p.22 / Chapter 2.3.3 --- Culture conditions for production of extracellular enzymes --- p.23 / Chapter 2.3.3.1 --- Tyrosinase --- p.23 / Chapter 2.3.3.2 --- Laccase --- p.23 / Chapter 2.3.3.3 --- Manganese-dependent Peroxidase and Lignin Peroxidase --- p.23 / Chapter 2.3.3.4 --- Cellulytic and Xylanolytic enzymes --- p.24 / Chapter 2.3.3.5 --- Lipase --- p.25 / Chapter 2.3.4 --- Culture conditions for studying properties of cellulases of V. volvacea --- p.26 / Chapter 2.3.4.1 --- CMCase --- p.26 / Chapter 2.3.4.2 --- "CMCase, FPase and β-Glucosidase" --- p.26 / Chapter 2.3.4.3 --- β-Glucosidase --- p.26 / Chapter 2.4 --- Enzyme assay --- p.27 / Chapter 2.4.1 --- Tyrosinase --- p.27 / Chapter 2.4.2 --- Laccase --- p.27 / Chapter a. --- o-Tolidine Method --- p.27 / Chapter b. --- ABTS Method --- p.28 / Chapter c. --- Syringaldazine Method --- p.28 / Chapter 2.4.3 --- Lignin peroxidase --- p.29 / Chapter 2.4.4 --- Manganese-dependent peroxidase --- p.29 / Chapter 2.4.5 --- Exoglucanase (avicelase) --- p.30 / Chapter 2.4.6 --- Endoglucanase (carboxymethylcellulase or CMCase) --- p.31 / Chapter 2.4.7 --- Filter paper digesting enzyme (FPase) --- p.32 / Chapter 2.4.8 --- P-Glucosidase --- p.32 / Chapter 2.4.9 --- Xylanase --- p.34 / Chapter 2.4.10 --- β-Xylosidase --- p.34 / Chapter 2.4.11 --- Lipase --- p.36 / Chapter 2.5 --- Other analytical methods --- p.36 / Chapter 2.5.1 --- Determination of phenol oxidase activity by the Bavendamm reaction --- p.36 / Chapter 2.5.2 --- Qualitative evaluation of CMCase by Congo red staining --- p.37 / Chapter 2.5.3 --- Effect of phenolic monomers and tannic acid on CMCase activity of V. volvacea --- p.38 / Chapter 2.5.4 --- Protein determination --- p.39 / Chapter 2.5.5 --- Non-denaturing gel electrophoresis pattern of fungal laccases --- p.39 / Chapter 2.6 --- Chemicals --- p.39 / Chapter 3. --- Results / Chapter 3.1 --- Growth and Nutritional characteristics --- p.44 / Chapter 3.1.1 --- Fungal growth on defined and non-defined culture media --- p.44 / Chapter 3.1.2 --- Effect of carbon source on fungal --- p.45 / Chapter 3.1.3 --- Effect of pH on fungal growth --- p.45 / Chapter 3.2 --- Effect of lignin-related phenolic monomers and tannin derivatives on fungal growth --- p.45 / Chapter 3.2.1 --- Effect of lignin-related phenolic monomers on fungal growth --- p.45 / Chapter 3.2.2 --- Effect of tannin derivatives on fungal growth --- p.61 / Chapter 3.3 --- Phenol Oxidase --- p.67 / Chapter 3.3.1 --- Phenol oxidase --- p.67 / Chapter 3.3.1.1 --- Guaiacol-reacting enzyme --- p.67 / Chapter 3.3.1.2 --- o-Anisidine oxidizing enzyme --- p.68 / Chapter 3.3.2 --- Tyrosinase --- p.69 / Chapter 3.3.3 --- Laccase --- p.69 / Chapter 3.3.3.1 --- "Laccase detected by o-Tolidine, ABTS Syringaldazine" --- p.69 / Chapter 3.3.3.2 --- Effect of pH on laccase activity --- p.69 / Chapter 3.4 --- Lignin-Transforming Enzymes --- p.73 / Chapter 3.4.1 --- Lignin peroxidase (LP) --- p.73 / Chapter 3.4.2 --- Manganese-dependent peroxidase (MnP) --- p.74 / Chapter 3.5 --- Cellulases --- p.78 / Chapter 3.5.1. --- Cellulases of V. volvacea --- p.78 / Chapter 3.5.1.1 --- Qualitative estimation of cellulose-degrading enzymes of V. volvacea grown on different substrates --- p.78 / Chapter 3.5.1.2 --- Influence of pH and temperature --- p.79 / Chapter 3.5.1.3 --- Cellulolytic activities in cultures grown on cellulose --- p.83 / Chapter 3.5.1.4 --- Cellulolytic activities in cultures grown on paddy straw --- p.91 / Chapter 3.5.1.5 --- β-Glucosidase activity in cultures grown on cellobiose --- p.91 / Chapter 3.5.1.6 --- Effect of lignin-related phenolic monomers and tannic acid on CMCase of V. volvacea --- p.95 / Chapter 3.5.2 --- Cellulases of P.sajor-caju --- p.96 / Chapter 3.5.3 --- Cellulases of L. edodes --- p.96 / Chapter 3.6 --- Xylanase --- p.96 / Chapter 3.6.1 --- "Xylanase of V. volvacea, strain V34" --- p.96 / Chapter 3.6.2 --- Xylanase of P.sajor-caju --- p.100 / Chapter 3.6.3 --- Xylanase of L. edodes --- p.100 / Chapter 3.7 --- Lipase of V. volvacea --- p.103 / Chapter 4. --- Discussion / Chapter 4.1. --- Carbon nutrition and pH for fungal growth --- p.104 / Chapter 4.1.1 --- Carbon nutrition --- p.104 / Chapter 4.1.2 --- pH --- p.104 / Chapter 4.2 --- "Effect of lignin-related phenolic monomers and tannin derivatives on fungal growth of L. edodes, P. sajor-caju and V, volvacea" --- p.105 / Chapter 4.2.1 --- Lignin-related phenolic monomers --- p.105 / Chapter 4.2.2 --- Tannin derivatives --- p.107 / Chapter 4.3 --- "Production of phenoloxidases by V. volvacea, L. edodes and P. sajor-caju" --- p.108 / Chapter 4.3.1 --- Guaiacol- and Anisidine reacting enzymes and Tyrosinase --- p.108 / Chapter 4.3.2 --- Laccase --- p.109 / Chapter 4.4. --- "Lignin-degrading Enzymes of V. volvacea, P. sajor-caju and L. edodes" --- p.110 / Chapter 4.5. --- "Cellulolytic and Hemicellulolytic Activity of V. volvacea, P.sajor-caju and L. edodes" --- p.113 / References --- p.118 / Appendix1 --- p.129

Human activities that disrupt soil properties are fundamentally changing ecosystems. Soil degradation decreases microbial abundance and activity, leading to changes in nutrient availability, soil organic matter, and plant growth and establishment. Land use and land cover change are widespread and increasing in semiarid regions of the southwestern US, which results in reductions of native plant and microbial abundance and community diversity. Here we studied the effects of soil degradation and amendments (biochar and woodchips) on microbial activity, soil carbon and nitrogen availability, and plant growth of ten semi-arid plants species native to the southwestern US. Results show that woodchip amendments result in poor overall plant growth, while biochar amended soils promoted plant growth when soil quality was reduced. Additionally, amendments had a strong influence on microbial activity, while the presence and species identity of plants did not. Biochar amended soils led to increases in the potential activities of enzymes involved in the degradation of carbon, nitrogen, and phosphorus rich substrates. Woodchips, caused an increase of potential activity in enzymes involved in the degradation of sugar and proteins. These results show that microbes and plants respond differently to soil treatments and suggest that microbial responses may function as earlier indicators of the success of re-vegetation attempts.

Thesis (M.S.)--Brock University, 2005. / Includes bibliographical references (leaves 134-165). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.