If E coli presented with glucose lactose,use mainly glucose until gone, then use lactose act ose 阝- galactosidase CH2OH CH2OH O、OH H O OH Glucose Galact ose OH lactose mucose epImerase lactose g ly coly sisO OH CH2OH O OH CH2OH O HO HO OH OH galactose glucose lactose lac t ose Glucose Galact ose ep im erase g ly co ly sis -galactosidase If E.coli presented with glucose & lactose, use mainly glucose until gone, then use lactose