Abstract: A carbonaceous feedstock can be converted into a chemical product having a higher commercial value, by introducing the carbonaceous feedstock into a plasma torch under conditions selected to generate a synthetic gas mixture having a tailored composition, and then introducing the synthetic gas mixture into a microbial digester configured to convert the synthetic gas mixture into the chemical product. The composition of the synthetic gas mixture produced by the plasma torch can be quickly modified to yield an optimal quality and quantity required by the microbial digester, and the quantity and stoichiometric ratio can be quickly varied if the quantity or composition of the synthetic gas mixture being provided is not appropriate for the microbial digester, enabling greater efficiency to be achieved as compared to systems where the quality and quantity of the synthetic gas mixture cannot be easily changed.