Integrated ultrasound-mediated sugaring-out extraction of erythromycin from fermentation broth

Abstract

• UMSO extraction reduced the extraction time (by 1/10th). • UMSO extraction reduced one step in downstream processing. • Antimicrobial activity and structure of erythromycin was unaltered. • Cell morphology was intact after UMSO extraction of erythromycin. This work investigates ultrasound-mediated sugaring-out extraction (UMSOE) of erythromycin from real fermentation broth. Various process conditions of the UMSOE system (time, pulse mode, probe position, temperature, acetonitrile (ACN)/water ratio, and glucose concentration) were evaluated for a model system (consisting of erythromycin) and optimized. Under the optimized process conditions (extraction time 6 min; pulse mode 20 s ON and 40 s OFF; probe position, interphase; temperature 4 °C; ACN/water ratio 1 and glucose 160 g/L), the maximum extraction efficiency of 91.6% w/w was attained. UMSOE of erythromycin from real fermentation broth resulted in 87 ± 1.88% extraction of erythromycin which was comparable with the model system and earlier studies. It is to be noted here that the time required for UMSOE is just 1/10th of sugaring-out extraction without ultrasound (control). It was carried without removing the cells, a practice followed at the industrial level and earlier studies. Further, the effect of UMSOE on antimicrobial activity and structure of erythromycin and morphology of Saccharopolyspora erythraea was also studied. The antimicrobial activity and structure of the erythromycin separated using UMSOE were comparable with the standard erythromycin. Also, the images of S. erythrea showed that the UMSOE had an insignificant effect on the morphology of the cells and the release of intracellular material. Thus, it can be concluded that UMSOE speeded up the extraction process (by reducing time and a cell removal step) and maintained the erythromycin activity intact. The physical and chemical effects of ultrasound helped intensify the process on a multifold basis.