Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains viii, 91 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references (p. 67-69).

Thesis (Ph. D.)--University of Wisconsin, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

M.Sc. (Biochemistry) / Pseudomonas, as originally defined by Migula (1894), was a genus encompassing an assembly of rod-shaped, Gram-negative, aerobic gammaproteobacteria, possessing one or more polar flagella for motility. This vague description resulted in the misclassification of polarly flagellated proteobacteria that had not been completely characterized. Re-evaluation of the taxonomy of Pseudomonads was set into motion by advancements in molecular biology. Following this revision, Pseudomonads were clustered based on the homogeneity in their 16S rRNA sequence (Anzai et al., 2000). Research on Pseudomonas species has gained momentum owing to their significant prospects in biotechnological processes. Their exploitation for use as cleaning, biocontrol and bioremediation agents dates back to the 1980s (Sebastian and Kolattukudy, 1988; Weller, 1988)...

M. Tech.

The aim of our study was to determine whether Polyphenon G (PPG, a concentrated Camellia sinensis extract) and the individual compounds in PPG had activity against phytopathogenic fungi in vitro and in vivo. The present study reports on the sensitivity of twenty different phytopathogenic fungal species to extracts from black-, green- and rooibos tea extracts, concentrated green tea extract (Polyphenon G), caffeine, theanine, epigallocatechin gallate (EGCg), epicatechin gallate (ECg), epigallocatechin (EGC), and epicatechin (EC), and Polyphenon G combined with caffeine. The inhibition of fungal growth by the compounds was as follows (in decreasing order): caffeine > EGCg ECg > EGC EC > Polyphenon G > green tea extracts black tea extracts > rooibos tea extracts theanine. In some cases the Polyphenon G and caffeine combination reduced the IC50 values for both the compounds, indicating a synergistic effect. Phytophthora nicotianae and P. capsici were most sensitive to all the compounds, while Rhizopus stolonifer and Penicillium expansum were least sensitive. PPG and caffeine was subsequently tested individually and in combination in a greenhouse trial against seven pathogens on four crops. The combinations of Polyphenon G and caffeine gave the best overall results and effectively controlled Fusarium solani on cucumber, P. capsici and Sclerotium rolfsii on tomato, Sclerotinia sclerotiorum and Pythium F-group on lettuce. PPG individually significantly inhibited the growth of Sphaerotheca fuliginea of zucchini squash plants. In efforts to determine the mode of action of PPG, caffeine and the combination thereof, methods used in our study included determining total phenolic content by means of the Folin-Ciocalteu reagent, thin layer chromatography (TLC) bioautography to identify possible anti-microbial compounds and high performance liquid chromatography (HPLC) for identifying induced compounds based on standards included in the analysis. Results showed that ferulic, salicylic and caffeic acids increased in uninfected lettuce plants treated with a combination of PPG and caffeine. These results indicate that either the phenolic compounds in the treatments were accumulated in the roots or that the treatments induced de novo synthesis in the plants to increase the production of phenolic compounds or that the treatments caused induction of resistance in the plant. The results of the current study demonstrate the potential for tea (C. sinensis) extracts to be developed as effective crop protection agents against a range of plant diseases on a variety of crops. / Dissertation (MSc)--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

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