Catalyzes the isomerization of trans-2-decenoyl-ACP to cis-3-decenoyl-ACP (By similarity). Required for survival at low pH. (2E)-decenoyl-[ACP] = (3Z)-decenoyl-[ACP] Lipid metabolism; fatty acid biosynthesis. Homotetramer. Mutants do not produce monounsaturated fatty acids, exhibit reduced glycolytic capability and altered glucose-PTS activity, and are extremely sensitive to low pH. Belongs to the enoyl-CoA hydratase/isomerase family.