11-73: Preliminary study to evaluate the growth lactic acid bacteria in xylose

Lactic acid  and its derivatives have many applications in foods, chemical, pharmaceutical industries and biodegradable polymers, and can be produced  by different carbon source (glucose, sucrose, galactose) using lactic acid bacteria. The aim this work it is study the xylose conversion to lactic acid production and growth of Lactic Acid Bacteria (LAB).  Xylose is the second most abundant sugar present in sugarcane bagasse and can be important sugar in the organic acids production. The fermentation was carried out in batch bioreactor (2 L working volume) under anaerobic conditions for about 120 hours. Temperature, pH and agitation speed were controlled at  35oC,  5.5 and  200 rpm, respectively. The initial xylose concentration was 12.5 g/L. Aliquots of the fermented broth were collected over time for determining lactic acid, acetic acid, sugar, and biomass concentration. A liquid chromatographic system equipped with an Aminex HPX-87H column and an UV and RI detection system was used to analyze xylose, lactic acid, and acetic acid.  Biomass was determined by gravimetry and  absorbance measurement using spectrophotometer UV-Vis and a wavelength of 600nm. Through the results obtained was possible to realize a considerable growth of Lactic Acid Bacteria when xylose is employed as carbon source.