A continuous particle fluidized-bed reactor is being developed for the simultaneous fermentation and purification of lactic acid. Unlike conventional fermentation schemes, the biparticle fluidized bed does not require the addition of salts for reactor pH control and product separation as the inhibitory product is removed directly from the reactor. This minimizes process waste and enhances reactor efficiency. This work has screened a series of adsorbents for possible utilization in the biparticle fluidized-bed fermentation of lactic acid by immobilized Lactobacillus delbreuckii. Capacity, specificity, regenerability, and kinetics were investigated. Although a resin exhibiting all of the desired properties has yet to be found, Remex 425 appears satisfactory and will be utilized in initial process demonstration as resin screening continues.