There are significant worries about the impact of heavy metal pollutants in soils during urbanisation and industrialisation in the developing world. Routine chemical analysis of soils is used to characterise the concentration of metals translocated by point source and diffuse actions. This fails to put in context the bioavailability or potency of these analytes. Biosensors offer a novel and direct method for hazard assessment of soils impacted with anthropogenic contamination. However, few significant examples of thorough applications of the biosensor in environment have been confirmed. This thesis makes use of comprehensively characterised biosensors for the applications to different environmental matrices. The objective was to apply and evaluate the performance of biosensors in determining the bioavailable fraction of heavy metals in the environment in conjunction with chemical analysis data. Both constitutively marked and metal induced biosensors were optimised and applied, but only the constitutively marked biosensor was responsive to a range of soils and elements of concern. As the matrix that the biosensors were exposed to became increasingly complex, the biosensors' performance became more difficult to interpret. For the metal induced biosensor, the response to standard aqueous samples was predictable as the relationship between chemical analysis data and biosensor predicted data was strong. By contrast, the performance of the metal induced biosensor was poor in soil samples which were historically contaminated (Chapter 9). This could become impacted by the soil characterisation, such as the presence of eo-contaminants, soil associated carbon or variations in soil pH. The constitutively-marked biosensors offered greater predictability of response and this is the reason why these are widely adopted in soil applications. Bacterial biosensors provide a useful tool for assessing the bioavailable fraction of analytes in soils and for complementing chemical analysis. If matrix matched control samples can be collected, then this technology can be applied to a wide range of contrasting soils with a suite of contaminants to aid in the development of generic soil hazard evaluation.