Efficient Biofilm-Based Fermentation Strategies by eDNA Formation for <scp>l</scp>-Proline Production with <i>Corynebacterium glutamicum</i>

Abstract

Biofilms could provide favorable conditions for the growth of cells during industrial fermentation. However, biofilm-immobilized fermentation has not yet been reported in <i>Corynebacterium glutamicum</i> (<i>C. glutamicum</i>), one of the main strains for amino acid production. This is mainly because <i>C. glutamicum</i> has a poor capability of adsorption onto materials or forming an extracellular polymeric substance (EPS). Here, an engineered strain, <i>C. glutamicum</i> Pro-Δ<i>exeM</i>, was created by removing the extracellular nuclease gene <i>exeM</i>, 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 <i>C. glutamicum</i> biofilm could be favorable for l-proline production, which could be extended to other industrial applications of <i>C. glutamicum</i>, and the strategy may also be applicable to the engineering of other strains.