SCREENING OF LACTIC ACID PRODUCING MICROORGANISMS WITH ALTERNATIVE SUBSTRATES

In Brazil, the production of alcohol and sugar and recently the biodiesel production generate lignocellulosic residues and crude glycerol with biotechnological potential. Lactic acid (LA) is a potential product since it is the raw material for producing biodegradable plastic. The present work aimed to select microorganisms capable of using the bagasse hydrolysate or crude glycerol as substrate for LA production. Sugarcane biomass was steam exploded at 18 bar and 4 min, concentrated by evaporation and autoclaved at pH 2, and was adjusted to 6 by last. The crude glycerol was obtained from a biodiesel production plant. 14 strains were used for performing shaker tests using this substrates for LA production. The initial concentration was 20 g.L-1 of sugars and 10 g.L-1 for crude glycerol. The experiments were performed for 48 h at 30 °C and 37 °C. The LA isomers quantification was done by HPLC. The studied strains, four of them produced quantities above 2.0 g.L-1, with highest production of 4.5 g.L-1 with hydrolysate. With the glycerol only one showed production of 3.5 g.L-1. This initial study showed that, among the strains evaluated, there are potential microorganisms for the development of a biotechnological process for LA production.