An optimized biocatalyst for efficient conversion of CH4 and CO2 into bioproducts

Aspartate-family amino acids are the most important essential amino acids in human and animal nutrition. These amino acids are currently commercially produced from either microbial fermentation using food-derived feedstocks or by a chemical method utilizing highly toxic petrochemical raw materials. The major amino acids producers are looking for alternative non-food feedstocks to offset the rising cost of food-based feedstocks. In addition, sugar-based bioprocess for production of methionine has not been commercially successful due to the energy-intensive biosynthetic pathway. Availability of cheaper and energy dense molecules such as methane and methanol offers opportunity to develop a cost-competitive bioprocess for methionine. However, a number of challenges remain in utilization of methanotroph including inefficient C3 (pyruvate and phosphoenolpyruvate) carboxylation, complex regulation of metabolic pathways, etc. The goal of this proposal is to engineer methanotroph for efficient C3 carboxylation. We will accomplish this by expression of multiple genes encoding carboxylases. Native genes involved in decarboxylation of C4 molecules (oxaloacetate, malate, etc.) will be deleted to prevent the futile cycles. The proposed project will lead to an engineered optimized methanotroph that efficiently channels methane and CO2 towards a common native intermediate that can be used to produce a number of bioproducts including methionine. Our technology will reduce dependence on the highly toxic petrochemical derived raw materials and generation of toxic wastes during the production of methionine. Usefulness of the optimized biocatalyst to convert methane and CO2 into a number of bioproducts opens additional market opportunities. The anticipated result of this SBIR Phase 1 research project is establishment of a bioprocess that will produce methionine from methane and CO2 at competitive cost with the current petrochemical-based feedstocks. Key words: natural gas, biogas, amino acid, methanotroph, bioproduct, renewable.