Efficient Biofilm-Based Fermentation Strategies by eDNA Formation for <scp>l</scp>-Proline Production with <i>Corynebacterium glutamicum</i>
Peifang Ren, Tianpeng Chen, Na Liu, Wenjun Sun, Guang Hu, Ying Yu, Bin Yu, Pingkai Ouyang, Dong Liu, Yong Chen
Abstract
Biofilms could provide favorable conditions for the growth of cells during industrial fermentation. However, biofilm-immobilized fermentation has not yet been reported in Corynebacterium glutamicum (C. glutamicum), one of the main strains for amino acid production. This is mainly because C. glutamicum has a poor capability of adsorption onto materials or forming an extracellular polymeric substance (EPS). Here, an engineered strain, C. glutamicum Pro-ΔexeM, was created by removing the extracellular nuclease gene exeM, which effectively increased extracellular DNA (eDNA) in the EPS and cell adhesiveness onto carrier materials. In repeated-batch fermentation using the biofilm, l-proline production increased from 10.2 to 17.1 g/L. In summary, this research demonstrated that a synthetic C. glutamicum biofilm could be favorable for l-proline production, which could be extended to other industrial applications of C. glutamicum, and the strategy may also be applicable to the engineering of other strains.