Bioethanol is an alcohol produced by microbial fermentation process. To date, there are a significant number of techniques that have been developed to improve the production of bioethanol, including continuous culturing, continuous fermentation by cell recycling, and immobilization of yeast cells. Among the techniques, immobilization technique has reached the attention. Immobilization technique is one of process where the movement of enzymes, cells and organelles in restricted space. There four types of immobilization method like physical adsorption, entrapment, microcapsules and self aggregation of cell by flocculation. In this study, the microbial ethanol producer (MEP) which is Saccharomyces cerevisiae been immobilized via physical adsorption method onto hydroxyapatite (HAp) surface, a biomaterial based instead of using organic immobilized materials. HAp is the most stable calcium phosphate salt among the calcium phosphate phases and the most abundant minerals which are found in living organisms are calcium carbonate and calcium phosphate. Primarily, the carrier should be characterized and the effect of each paramaters used to produce HApwas analyzed by Design Expert® Software version 7.1.5. There are three parameters used to optimize the size of particle (sintering temperature, agitation rate and aging time). The optimum condition of particle producing was obtained at 700 °C of sintering temperature, 300 rpm of agitation rate and 16 hours of aging time. Prior to bioethanol fermentation, the most commonly employed microorganism for bioethanol generation is using Saccharomyces cerevisiae, the baker’s yeast which offering high ethanol yields up to 90-97% of the theoretical.
