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The effects of the insecticide diflubenzuron (DFB) on the growth characteristics of two gram negative soil bacterial isolates were examined. The bacterial isolates were grown in the presences of varying amounts of DFB and showed no apparent change in cell numbers, over time, when compared to control cultures. However, one of the two isolates tested showed a delayed response in chitinase production, over the same time period, as determined by radioisotopic methodology. Chitinase fractions obtained from cell free culture supernatants, concentrated by ultrafiltration and purified by affinity chromatography, were examined for activity in the presence of DFB. High performance liquid chromatography (HPLC) techniques were utilized in the identification and quantification of products from control and experimental samples. Due to the loss of overall chitinase activity in the supernatants, this technique proved ineffective in determining chitinase response to DFB. / Department of Biology

Antarctica provides some of the most extreme environments on earth. Low temperatures, low water availability and nutrient deficiency are contributing factors to the limited colonisation of Antarctic biotopes, particularly in the continental Dry Valleys. The survival of microorganisms in this harsh continent provides the basis for the significance of this study. This study aimed to explore microbial phylotypic diversity across a 500 m altitudinal transect in the Miers Dry Valley, Ross Desert, East Antarctica. The study also attempted to infer from phylogenetic data, the possible presence of indicative phenotypes which might contribute to a functional microbial community.

The major objective of this study was to investigate soil ammonia-oxidizing bacterial diversity and composition associated with plant roots of Proteaceae plants and to compare it with non-plant associated soil.

<p>Soil communities are regarded as among the most complex and diverse assemblages of microorganisms with estimated bacterial numbers in the order of 10â?¹ cells.gâ?»&sup1 / . Studies on extreme soils however, have reported lower cell densities, supporting the perception that the so-called extreme environments exhibit low species diversity. To assess the extent of microbial diversity within an extreme environment, the mineral soils of the Dry Valleys, Ross Dependency, Eastern Antarctica were investigated using 16S rDNA analysis.</p>

<p>The microbial life of sub-Antarctic islands plays a key role in the islands ecosystem, with microbial activities providing the majority of nutrients available for primary production. Knowledge of microbial diversity is still in its infancy and this is particularly true regarding the diversity of micro-organisms in the Antarctic and sub-Antarctic regions. One particularly important functional group of micro-organisms is the diazotrophs, or nitrogen-fixing bacteria and archaea. This group have not been well studied in the sub-Antarctic region, but play an important role in the nutrient cycling of the island. This thesis explored the diversity of nitrogen-fixing organisms in the soil of different ecological habitats on the sub-Antarctic Marion Island.</p>

Thesis (M.S. - Agricultural Chemistry and Soils)--University of Arizona. / Bibliography: leaves 106-129.

Thesis (Ph. D.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (leaves 126-153). Also available via the World Wide Web.

Thesis (M.S. - Hydrology and Water Resources Administration)--University of Arizona, 1987. / Includes bibliographical references (leaves 166-176).

Thesis (Ph.D.) in Ecology and Environmental Science--University of Maine, 2005. / Includes vita. Includes bibliographical references (leaves 117-128).