Fecha de publicación: -- Fuente: WIPO "tomato" A process for the production of methacrylic acid and/or a methacrylic acid ester comprising the step of: (a) biologically converting hydroxyisobutyric acid (HIBA) to hydroxyisobutyryl-CoA by the action of a CoA ligase. The invention extends to a process for the production of methacrylic acid and/or a methacrylic acid ester comprising the step of: (b) biologically converting (R) hydroxyisobutyryl-CoA to methacrylyl-CoA by the action of a crotonase. The invention also extends to microorganisms adapted to conduct one or both of steps (a) and (b).