Luciana Fontes Coelhoa, Cristian J. Bolner de Limaa, Jonas Contieroa*
a UNESP – Univ. Estadual Paulista, Biological Sciences Institute, Department of Biochemistry and Microbiology , Rio Claro, SP, Brazil.
The polymer made by using L(+) lactic acid (PLLA) has a melting temperature of 175 °C. However, the melting temperature of this polymer can be increased by blending with D(-) lactic acid (PDLA), producing a stereocomplex with melting temperature (Tm) around 230 °C. The aim of this study was to evaluate the potential use of different types of cheap agro-industrial substrates (cheese whey, sugarcane juice, sugarcane molasses, autolyzate yeast, corn steep liquor and protein seed cotton for the D (-) lactic acid production by Leuconostoc mesenteroides. The variables sugarcane juice and autolysate yeast increased lactic acid production more than the other agro-industrial substrates. Therefore, the concentrations of these two components were further optimized by using Plackett Burman design and response surface methodology. The maximum lactic acid production of 60.2 g/L was obtained when the optimum values of sugarcane juice and yeast autolysate were 116.9 g/L and 44.25 g/L respectively.
Keywords: Response surface methodology; Medium optimization; D(-) Lactic acid; residues.