This paper deals with the modelling and control of the hatch kinetic of xanthan gum, a microbial polysaccharide synthesized by Xanthomonas campestris—ITS-342, obtained from the Institute for Bioproducts, Plovdiv (Bulgaria). A nonstructure model is proposed. On this basis the attention is focussed on the synthesis of the adaptive linearizing control law with dissolved oxygen as an input action. Some simulations results are discussed.