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Typescript. Thesis (Ph. D.)--University of Hawaii, 1949. Bibliography: leaves 42-47.

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This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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Peatlands make up 3% of the earth's land surface and contain about one third of the C contained in soils globally. The role of peatlands in the C cycle is as a net sink. Organic matter accumulates in these areas because the rate of net primary productivity (NPP) exceeds the rate of decay. Peatlands are often harsh environments, characterized by cold, wet and anoxic conditions, therefore it is not accelerated NPP which exerts the main control over the accumulation of peat, but the slow rate of decomposition. During the decomposition process, nearly all organic matter passes through the soil microbial pool, and so the soil microbial community is an important factor in the decomposition process. Despite the obvious importance of the soil microbial community in decomposition in peatlands, our knowledge of their role in peatland C cycling is still largely limited. This thesis addresses some aspects of the soil microbial community and investigates their role in decomposition in a raised mire. The soils in a raised mire system may be categorized according to their nutrient input into nutrient rich, mineral soils and soils of the lagg fen, and nutrient poor, soils of the mire expanse. The soil microbial community in the three soils was characterized in terms of size, activity and composition. The size of the soil microbial community in the soils of the mire expanse was small in comparison with that of the mineral soils and soils of the lagg fen, however it was very active. The hypothesis that nutrients restrict the size of the soil microbial community in the soils of the mire expanse was tested. The data showed that nutrients did not significantly effect the size of the soil microbial community. Litterbags were used to investigate the decomposition of a range of plant species found on the different soils and mass loss and C02 production were used as indicators of decomposition. C02 production was a more sensitive and reliable measure of decomposition than mass loss. The size of the soil microbial community was an important factor in decomposition rate. Litter quality of the above ground biomass was not related to decomposition rate. The relationship between the size of the microbial community in contact with decaying plant material and decomposition was investigated. In this study, microbial colonization of decaying litter was not correlated with the measure of litter quality used. This work has provided baseline information the environmental factors that influence decomposition and future work should focus on investigating the changes in the soil microbial community during the decomposition process.

Burkholderia cepacia complex (Bcc) bacteria reside in soil, plant rhizospheres, and water, but the prevalence of Bcc in outdoor environments is not clear. In this study, we sampled a variety of soil and rhizosphere environments with which people may have contact: playgrounds, athletic fields, parks, hiking trails, residential yards and gardens. A total of 9l soil samples was obtained from three large U.S. cities (Philadelphia, PA, Cleveland, OH, and Portland, OR). In the first phase of the study, putative Bcc isolates were recovered on Burkholderia cepacia selective agar (BCSA) and trypan blue tetracycline medium (TBT). Isolates were sent to the Burkholderia cepacia Referral Laboratory and Repository, where they were identified using biochemical tests, growth at 32��C, and polymerase chain reaction (PCR) assays targeting both rRNA and recA gene sequences. Bcc isolates were genotyped by using RAPD, PFGE and rep-PCR. A total of 1013 bacterial isolates were examined, and 68 were identified as B. cepacia complex. The majority of these were B. pyrrocinia or genomovar VII (B. ambifaria); however, a few genomovar III isolates were also recovered. Fourteen (15%) of 91 soil samples yielded Bcc isolates. In the second phase of the study, DNA was extracted from 87 of the 91 soil samples and examined with PCR assays targeting Bcc 16S rRNA gene sequences. By using assays developed by LiPuma et al. (1999), 82% of the soil samples were positive for at least one Bcc genomovar, whereas 94% of samples were positive for at least one Bce genomovar using the Bauernfeind et al. (1999) assay system. Selected amplicons generated from four soil samples were cloned, and plasmids from multiple transformants (total=120) were screened by RFLP analysis. Among the clones evaluated from three of four soil samples, 90% or more had the "Burkholderia" RFLP pattern. In the remaining soil sample, only 9.5% of the evaluated clones displayed this profile. Sequence analysis of the 463bp 16S rRNA inserts from eight clones with the "Burkholderia" RFLP pattern indicated that all were from members of the Bcc. However, the four soil samples from which these clones were generated did not yield isolates identified as Bcc. This study indicates that the use of selective media may not be the best way to estimate the environmental prevalence of Bcc in soils. The natural populations of Bcc in soils with which people commonly have contact may be much higher than previously estimated. / Graduation date: 2002