Biocatalytic conversion systems and methods of producing and using same that have improved yields are disclosed. The systems and methods involve co-fermentation of sugars and gaseous substrates for alcohol, ketone, and/or organic acid production. The systems and methods may include biocatalytically converting at least one sugar substrate into at least one of alcohol, at least one ketone, and/or at least one organic acid. The systems and methods may further include biocatalytically converting gases that comprise CO2 and H2 to at least one alcohol and/or at least one organic acid, thereby adding extra revenue to biorefineries.