Optimization of medium using response surface methodology for erythromycin production by Saccharoplyspora Erythraea

Abstract

For the past decades, it was obvious and understood that there was a great industrial interest for optimization of medium components by statistical method for high erythromycin antibiotic production by Saccharopolyspora erythraea (formerly known as Streptomyces erythraea). In this research, medium components that were already screened in classical method by previous researcher were further optimized using statistical method known as Response Surface Methodology (RSM). Maximum erythromycin and cell dry weight observed in shake flasks studies after medium optimized in RSM were 412.5 mg/l and 4.9 g/l, respectively. It was found that by using optimized medium it increased the production of erythromycin and cell dry weight by 30.43% and 17.3% . Optimization of medium components in statistical method in which media components was first screened in full factorial using Plackett-Burman experimental design, showed that glucose and yeast extract had higher effect on erythromycin production. Further optimization was carried out in RSM using Box-Behnken experimental design in which optimized medium was selected. The optimized medium composed of g/L; glucose 45, yeast extract 8, sodium nitrate 4, dipotasium hydrogen phosphate 2.5, sodium chloride 1.0, and magnesium sulphate 0.5. This optimized medium was further studied in 16-L bioreactor using controlled and un-controlled pH conditions. For controlled pH bioreactor, the maximal erythromycin, and cell dry weight obtained were 567.5 mg/l and 5.65 g/l rspectively. It observed that the maximum erythromycin produced in controlled pH bioreactor was higher 12.9% than that cultivated in bioreactor under un-controlled pH condition and about 15.8% higher than that results obtained in shake flasks when used optimized medium. On the other hand, cell dry weight was about 17.7% higher when compared to cell produced in un-controlled bioreactor.