Conversion of CO2 into calcium carbonate using microorganism is one of the promising methods of reducing the increased level of CO2 in the atmosphere. In the present study, a novel strain of Corynebacterium flavescens was isolated from cow saliva and screened for CO2 hydration activity. First of all, the effect of C. flavescens on CaCO3 precipitation was studied under optimized conditions. Various factors such as CO2 concentration, protein concentration, pH of the reaction system, and temperature were then optimized for maximum CO2 precipitation into CaCO3 using free cell lysate. After that, C. flavescens cells were immobilized onto highly porous keratin microparticles functionalized with glutaraldehyde (0.6 % v/v) to enhance the CO2 conversion efficiency. Maximum immobilization of bacterial cells was achieved after 25 h at 4 degrees C under shaking conditions. The covalently immobilized C. flavescens particles showed a 1.35-fold increase in CaCO3 production compared to their free counterparts. Under repeated batch conditions, the relative production of CaCO3 for immobilized and free cells was 53.46 and 22.15 %, respectively, after 10 cycles. This study demonstrated the advantages of keratin microparticles as a support for the immobilization of C. flavescens and the efficient conversion of CO2 to CaCO3.