The present disclosure relates to an engineered microbe capable of improved productivity of fatty acid or fatty acid derivative. An NAD+-dependent 3-oxoacyl-ACP reductase or NAD+-dependent 3-oxoacyl-CoA reductase replaces or supplements the native NADP+-dependent 3-oxoacyl-ACP reductase so as to utilize the higher availability of NAD+ rather than NADP+ in the cell. Higher production, yield and titer of fatty acids are therefore obtained. Such microbes can be combined with other mutations to further improve yield of fatty acids or fatty acid derivatives.