use of response surface methodology in a fedbatch process for optimization of tricarboxylic acid cycle intermediates to achieve high levels of canthaxanthin from dietzia natronolimnaea hs1 in this work we applied statistical experimental design to a fedbatch process for optimization of tricarboxylic acid cycle tca intermediates in order to achieve highlevel production of canthaxanthin from dietzia natronolimnaea hs1 cultured in beet molasses a fractional factorial design screening test was first conducted on five tca cycle intermediates out of the five tca cycle intermediates investigated via screening tests alfaketoglutarate oxaloacetate and succinate were selected based on their statistically significant p005 and positive effects on canthaxanthin production these significant factors were optimized by means of response surface methodology rsm in order to achieve highlevel production of canthaxanthin the experimental results of the rsm were fitted with a secondorder polynomial equation by means of a multiple regression technique to identify the relationship between canthaxanthin production and the three tca cycle intermediates by means of this statistical design under a fedbatch process the optimum conditions required to achieve the highest level of canthaxanthin 13172 or 25 microg l1 were determined as follows alfaketoglutarate 969 mm oxaloacetate 868 mm succinate 851 mm