Simultaneous solid-liquid separation and primary purification of clavulanic acid from fermentation broth of Streptomyces clavuligerus using salting-out extraction system

Abstract

Clavulanic acid (CA) is usually used together with other β-lactam antibiotics as combination drugs to inhibit bacterial β-lactamases, which is mainly produced from the fermentation of microorganism such as Streptomyces clavuligerus. Recently, it is still a challenge for downstream processing of low concentration and unstable CA from fermentation broth with high solid content, high viscosity, and small cell size. In this study, an integrated process was developed for simultaneous solid-liquid separation and primary purification of CA from real fermentation broth of S. clavuligerus using salting-out extraction system (SOES). First, different SOESs were investigated, and a suitable SOES composed of ethanol/phosphate was chosen and further optimized using the pretreated fermentation broth. Then, the optimal system composed of 20% ethanol/15% K₂HPO₄ and 10% KH₂PO₄ w/w was used to direct separation of CA from untreated fermentation broth. The result showed that the partition coefficient (K) and recovery yield (Y) of CA from untreated fermentation broth were 29.13 and 96.8%, respectively. Simultaneously, the removal rates of the cells and proteins were 99.8% and 63.3%, respectively. Compared with the traditional method of membrane filtration or liquid-liquid extraction system, this developed SOES showed the advantages of simple operation, shorter operation time, lower process cost and higher recovery yield of CA. These results demonstrated that the developed SOES could be used as an attractive alternative for the downstream processing of CA from real fermentation broth.

Keywords: clavulanic acid; fermentation broth; salting‐out extraction; solid–liquid separation.