Author Description

This dissertation, "Microbial Ecology of Hot and Cold Desert Soils" by Subramanya, Rao, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Deserts are the most abundant terrestrial biome on Earth, and microbial processes assume a major role since environmental stress severely limits higher plant and animal life. A major hurdle to developing an understanding of microbial ecology in deserts has been the lack of knowledge at the fundamental biodiversity level. This is due to lack of research focus and also the inherent bias in 'traditional' microbial diversity estimates based upon cultivation. In this thesis an evaluation of culture-independent approaches employing both DNA and RNA from environmental samples was made with comparison to more traditional cultivation techniques. These were then applied to soils from hot and cold deserts, and along stress gradients from semi-arid to hyper-arid. A literature review was first conducted to assess the extent of current knowledge and identify critical knowledge gaps. The scientific study was then carried out as follows. The second chapter presents an evaluation of fungal taxa using cultivation, DNA and RNA based techniques. The findings indicated major taxa are revealed in all approaches, yet differences in less abundant taxa occur. The third chapter describes fungal assemblages in the soils of the McMurdo Dry Valleys, a cold polar desert. In this study, RNA based approaches tracked active fungal assemblages, whilst DNA and cultivation revealed additional taxa. Chapter four analyzed microbial communities in the Thar Desert, a hot monsoon desert in India. This study r