Abstract: The biological production of beta-hydroxyisovalerate (?HIV) using at least one non-natural enzyme. The non-natural enzyme for the biologically-derived ?HIV provides more beta-hydroxyisovalerate synthase activity than the wild-type parent. The non-natural enzyme having one or more modifications of substrate-specificity positions. The non-natural enzyme can be expressed in a microorganism, such as a yeast or bacteria, wherein the microorganism comprises an active ?HIV metabolic pathway for the production of ?HIV. Alternatively, the non-natural enzyme can be a ?HIV synthase used to produce ?HIV in a cell-free environment. The biological derivation of ?HIV eliminates toxic by-products and impurities that result from the chemical production of ?HIV, such that ?HIV produced by a non-natural enzyme prior to any isolation or purification process has not been in substantial contact with any halogen-containing component.

Abstract: The biological production of beta-hydroxyisovalerate (?HIV) using a non-natural microorganism. The non-natural microorganism for the biologically-derived ?HIV provides more beta-hydroxyisovalerate synthase activity than the wild-type parent. The non-natural microorganism can host a non-natural enzyme, such as the non-natural enzyme expressed in a yeast or bacteria, wherein the non-natural microorganism comprises an active ?HIV metabolic pathway for the production of ?HIV. The biological derivation of ?HIV eliminates toxic by-products and impurities that result from the chemical production of ?HIV, such that ?HIV produced by a non-natural microorganism prior to any isolation or purification process has not been in substantial contact with any halogen-containing component.

Abstract: The biological production of beta-hydroxyisovalerate (?HIV) using a non-natural microorganism. The non-natural microorganism for the biologically-derived ?HIV provides more beta-hydroxyisovalerate synthase activity than the wild-type parent. The non-natural microorganism can host a non-natural enzyme, such as the non-natural enzyme expressed in a yeast or bacteria, wherein the non-natural microorganism comprises an active ?HIV metabolic pathway for the production of ?HIV. The biological derivation of ?HIV eliminates toxic by-products and impurities that result from the chemical production of ?HIV, such that ?HIV produced by a non-natural microorganism prior to any isolation or purification process has not been in substantial contact with any halogen-containing component.

Abstract: The biological production of beta-hydroxyisovalerate (?HIV) using at least one non-natural enzyme. The non-natural enzyme for the biologically-derived ?HIV provides more beta-hydroxyisovalerate synthase activity than the wild-type parent. The non-natural enzyme having one or more modifications of substrate-specificity positions. The non-natural enzyme can be expressed in a microorganism, such as a yeast or bacteria, wherein the microorganism comprises an active ?HIV metabolic pathway for the production of ?HIV. Alternatively, the non-natural enzyme can be a ?HIV synthase used to produce ?HIV in a cell-free environment. The biological derivation of ?HIV eliminates toxic by-products and impurities that result from the chemical production of ?HIV, such that ?HIV produced by a non-natural enzyme prior to any isolation or purification process has not been in substantial contact with any halogen-containing component.

Abstract: The biological production of beta-hydroxyisovalerate (?HIV) using a non-natural microorganism. The non-natural microorganism for the biologically-derived ?HIV provides more beta-hydroxyisovalerate synthase activity than the wild-type parent. The non-natural microorganism can host a non-natural enzyme, such as the non-natural enzyme expressed in a yeast or bacteria, wherein the non-natural microorganism comprises an active ?HIV metabolic pathway for the production of ?HIV. The biological derivation of ?HIV eliminates toxic by-products and impurities that result from the chemical production of ?HIV, such that ?HIV produced by a non-natural microorganism prior to any isolation or purification process has not been in substantial contact with any halogen-containing component.

Abstract: The present invention provides modified bacterial cells and methods for using them. A modified bacterial cell can exhibit increased NADH oxidase activity, decreased ArcA activity, or the combination thereof. The methods include culturing a modified bacterial cell in aerobic conditions. The modified bacterial cell can produce less acetate during the culturing than the unmodified bacterial cell under comparable conditions. In some aspects, the modified bacterial cell produces a recombinant polypeptide, and the bacterial cell may produce more recombinant polypeptide than the unmodified bacterial cell under comparable conditions.