Systems and Synthetic Biology

Biography

Biography: Denis Kalemasi

Abstract

One of the possible applications of   synthetic biology   is the “creation” of recombinant bacteria able of producing building blocks. The latter have great potential since they can be used for the production of bio-bas ed polymers possibly replacing oil-derived plastics.  Lactic acid  (LA) is among the most requested compounds by the ch emical industry and is already largely employed for the production of its  polyesters  (i.e., polylactides), which are general purpose biodegradable and biocompatible plastic materials. Most LA produced worldwide is obtained by lact ic acid bacteria (LAB)-based fermentation. However, current processes depend on expensive feedstocks (e.g., glucose) or compete for food crops (e.g., corn). Cellulose, instead, is an ine xpensive substrate found in plant material-derived waste. Our aim is to construct a strain of Lactococcus lactis able to produce LA directly from cellulose (that is without prior enzymatic saccharification by commercial cellulases) by metabolic engineering. Only relatively few natural bacteria are able to grow with only cellulose as the substrate. Clostridium cellulovorans is one of them. To achieve our goal, we’ve introduced components of C. cellulovorans cellulose depolymerizing machinery into Lactococcus lactis. In particular, in this work we have shown that, by introducing only two C. cellulovorans glycosyl hydrolases, we were able to develop a recombinant L. lactis able of metabolizing short chains of cellulose (i.e., cellooligosaccharides with degree of polymerization up to 10) into L-LA with a yield close to 100%.