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The successes of bioremediation field studies with organochlorine respiring bacteria have proved the efficacy of the method to degrade contaminants such as 1,2-dichloroethane (DCA) in situ. The objective of this study was to demonstrate that a DCA degrading consortium, referred to here as AusDCA could be used to bioaugment a DCA contaminated acidic aquifer in situ. Functional characterisation experiments of AusDCA in batch cultures showed that the culture could dechlorinate high concentrations of DCA (6 mM) to ethene anaerobically at pH 5.5 and pH 6.5 and was not inhibited by approximately 15 µM of chloroform (CF). Phylogenetic analysis of an enrichment culture developed after several transfers into fresh medium and two dilution to extinction series of the parent AusDCA culture, identified two closely related Desulfitobacterium clades with sequences 93 and 95 % similarity to Desulfitobacterium metallireducens, a bacterium not known to dechlorinate DCA. Quantitative PCR (qPCR) of both clades demonstrated growth linked with DCA dihaloelimination to ethene at pH 5.5 and ethanol as the sole electron source. Characterisation of the putative DCA reductive dehalogenase, rdhA gene and the putative membrane anchoring protein, rdhB gene showed that the genes and the translated protein sequences were most similar to that of Dehalobacter strain WL, a DCA respiring bacteria from the Firmicutes phylum. This was surprising because not only is Dehalobacter a different genus to Desulfitobacterium, Dehalobacter was not characterised in community analysis of the parent AusDCA culture. A study to characterise the activity and mobility of filtered (planktonic) and unfiltered (planktonic and aggregated) AusDCA culture in aquifer matrix filled columns showed 1) the majority of the inocula had become entrained in the sandy aquifer and 2) aggregated cells are more active than planktonic cells. Application of the parent AusDCA culture in a bioaugmentation field study of the organochlorine contaminated acidic Botany Sands Aquifer, showed evidence of enhanced DCA degradation and longevity of up to 8 months in the bioaugmented well. This is based on in situ field and in vitro microcosm studies established using groundwater extracted 1 and 8 months after bioaugmentation and the detection of Desulfitobacterium specific to the AusDCA culture. This study has implications on bioaugmentation design relating to inoculation, feeding regime and pH buffering in sandy aquifers.

The management of significant bone defects, delayed and non-union of fractures can be extremely challenging. Development of specific treatment is hindered by an absence of information regarding the molecular events which regulate these processes. In this thesis, a bilateral cancellous bone defect model of the femur and tibia was developed in a rodent and the spatiotemporal profile of TGF-β, BMP 2 and 7, Smads 1, 4 and 5 characterised. Next, the capability of acid solution to augment healing was tested in both a bone defect and in a closed femoral fracture model. Finally, a long term oestrogen deficiency (OVX) rat model of postmenopausal osteoporosis was characterised and the spatiotemporal profiles of IGF-1, IGFR-1, MMP-1, MMP-3, MMP-9, MMP-13, TIMP-1, TIMP-2, BMP-2, BMP-4, BMP-7, TGF-β, Smad4, Smad7, VEGF, Flt-1, Ihh and FGF-2 were compared in femoral osteotomies between OVX and Sham groups. The bilateral cancellous defect model was successfully created with a number of advantages with which to recommend its use in future studies. TGF-β, BMP 2 and 7, Smads 1, 4 and 5 had characteristic spatiotemporal profiles during cancellous bone defect healing suggesting that they have a regulatory role. The results of the acid study were inconclusive and problems with substance delivery and maintenance at the desired site need to be addressed in the future to fully test this hypothesis. No significant differences were detected on histology or three-point mechanical testing between the fracture calluses of acid and control groups. In the final study, OVX rats after six months had significantly increased weight and decreased bone mineral density compared to their sham counterparts. A histological delay in osteotomy healing was observed in the OVX group but no significant differences on tensile testing were seen between OVX and Sham groups up to six weeks. Immunohistochemistry revealed that delayed healing may be due to the down-regulation of IGF-1, BMP-2, 4, and 7 and the up-regulation of MMP-3 in OVX compared to Sham groups. In conclusion, the results of this thesis give some insight into the molecular biology of bone defects and osteoporotic fractures. This information may also be useful in the development of specific treatments aimed at augmenting healing in bone defects and osteoporotic fractures.