Systems and Synthetic Biology

Biography

Biography: Loredana Tarraran

Abstract

      Lactic acid       (LA) is an extensively employed chemical. Notably, one of its main current applicati ons is for      synthesizing      biocompati ble and biodegradable plastic biopolymers, i.e.,      polylactide      (PLA), poly (lactic acid-co-lysine), poly (lactic acid-co-glycolic acid). The latter can be used for clinical application (i.e.,  tissue engineering) and especially PLA as packaging thus replacing traditional plastics. Lactic acid bacteria are the main natural LA producers. Both “green” property and cost-sustainability of LA-based polymers can be improved if LA is obtained by fermentation of abundant      cellulose     -based wastes produced by our society, such as municipal solid waste and agricultural by-products. In this light, the development of a     microorganism     able to both use    cellulose    as fermentation substrate and produce LA can achieve both environmentally an d economically sustainable   biopolymer   production. The aim of thi s work  was to obtain a recombinant     Lactococcus lactis    able to depolymerize cellulose by expressing heterologous    proteins    derived from the   cellulolytic   complex, i.e., the  cellulosome  of    Clostridium cellulovorans .  C. cellulovorans  cellulosome consists of enzyme subunits attached to a non-catalytic scaffold  protein . Such scaffoldin is anchored to  C. cellulovorans cell surface and allows optimal overall enzyme spatial organization, close to both cellulosic substrate and cell surface thus leading to improved cellular intake of cellulose hydrolysis products. In this work four different recombinant scaffoldins were constructed by molecular assembling of different protein domains of C. cellulovorans cellulosome. Engineered scaffoldins were successfully expressed by L. lactis. Their presence in cytosolic, extracellular and cell-wall fractions of L. lactis and their interaction with cellulosomal enzymes were analyzed by multiple approaches.