In this paper, the design of a decoupled adaptive controller for controlling the dissolved oxygen and glucose feeding simultaneously in fed-batch fermentation of methionine production is proposed. The synthesis of methionine at the cellular level is strictly regulated and its process dynamics shows a nonlinear interaction between dissolved oxygen and glucose concentration. The adaptive controller developed using a linear reference model for controlling these two variables, is designed in such a way that the system is decoupled. The performance of adaptive controller is evaluated in terms of simultaneous set point and trajectory tracking of dissolved oxygen (c(L)) and glucose (s) concentration Convergence of parameters is guaranteed by the Kalman-Meyer-Yakubovich criteria.