On the use of resting L. delbrueckii spp. delbrueckii cells for D-lactic acid production from orange peel wastes hydrolysates

The availability of pure isomers of lactic acid is a key aspect of the fabrication of polymers based on poly-lactic acid with enhanced mechanical and thermal properties. The main problems presented in the fermentation process to D-Lactic acid production are the costs derived from the carbon and nitrogen sources and the purification ones. In this work, the production is carried out using hydrolyzed orange peel wastes (OPW) as a cheap carbon source and a resting cells production process is developed to avoid the nitrogen source costs and to reduce them in the purification processes. A strategy to adapt the strain for the uptake of the mixture of sugars presented in the orange peel hydrolysate is developed in order to improve the fructose and galactose uptake rates. A D-lactic acid productivity important increase (6.72 g/L.h) is obtained from OPW hydrolysates using resting L. delbrueckii cells when grown on fructose during the growth stage.