The objective of Phase I work was to develop and test several specialized degradative microorganisms for remediation of chlorinated solvent- contaminated aquifers. The organisms constitutively degrade chlorinated solvents, and therefore, do not require the presence of toxic co-substrates to stimulate degradation. Constitutive toluene monooxygenase (TMO) variants of P. mendocina KR-i and several other strains were developed by first treating the cells with mutagenizing agents, then selecting variants that constitutively produced TMO. A constitutive TOM variant of P. cepacia G4 was also tested for TCE degradation. These microorganisms were also selected for adhesion-deficient variants, and thus able to penetrate aquifer sediments. Methods were developed for culturing the organisms to extremely high cell density, to reduce treatment costs, and so that they contain elevated levels of storage polymers. The storage polymers stimulate and prolong their activity to degrade more TCE in situ. The goal of the proposed Phase II work is to expand upon the success of Phase I work by demonstrating the utility of our specialized degradative microorganisms to remediate contaminated aquifers.