Reviews and compares the major types of bioreactors, defines their pros and cons, and identifies research needs and figures of merit that have yet to be addressed • Describes common modes of operation in bioreactors • Covers the three common bioreactor types, including stirred-tank bioreactors, bubble column bioreactors, and airlift bioreactors • Details less common bioreactors types, including fixed bed bioreactors and novel bioreactor designs • Discusses advantages and disadvantages of each bioreactor and provides a procedure for optimal bioreactor selection based on current process needs • Reviews the problems of bioreactor selection globally while considering all bioreactor options rather than concentrating on one specific bioreactor type