ENHANCEMENT OF CANTHAXANTHIN PRODUCTION FROM Dietzia natronolimnaea HS-1 IN A FED-BATCH PROCESS USING TRACE ELEMENTS AND STATISTICAL METHODS

Under fed-batch process conditions, the statistical analysis of trace elements was performed by application of Plackett-Burman design (for screening tests) and response surface methodology (for predicting the optimal points) to achieve the highest level of canthaxanthin production from Dietzia natronolimnaea HS-1. Plackett-Burman design was conducted on eleven trace elements (i.e., aluminum, boron, cobalt, copper, iron, magnesium, manganese, molybdenum, selenium, vanadium and zinc) to select out elements that significantly enhance the canthaxanthin production of D. natronolimnaea HS-1. Plackett-Burman design revealed that Fe(3+), Cu(2+) and Zn(2+) ions had the highest effect on canthaxanthin production of D. natronolimnaea HS-1 (P<0.05). These three elements were used for further optimization. By means of response surface methodology for the fed-batch process, the optimum conditions to achieve the highest level of canthaxanthin (8923+/-18 mu g/L) were determined as follow: Fe(3+) 30 ppm, Cu(2+) 28.75 ppm and Zn(2+) 27 ppm.