Revalorization of hemicellulosic trimming vine shoots hydrolyzates trough continuous production of lactic acid and biosurfactants by L. pentosus

摘要

This work proposes the utilization of trimming vine shoots hydrolyzates by Lactobacillus pentosus for lactic acid employing continuous culture and the evaluation of biosurfactants production. The treatment of hydrolyzates with sulphuric acid (prehydrolysis) allowed the solubilization of hemicelluloses to give liquors containing 18 g/L of xylose, 11.1 g/L of glucose, 4.3 g/L of arabinose and 4 g/L of acetic acid. Continuous fermentation of hemicellulosic hydrolyzates gave a Q_P = 3.10 g of lactic acid/L h and Y_(P/S) = 0.70 g of lactic acid/g of sugars for a dilution rate of 0.02 h~(-1) using 10 g/L of corn steep liquor and 10 g/L of yeast extract as nutrients. When nutrients were replaced by 20 g/L of distilled lees from white wine production the same results were obtained without interfering, lees, in the lactic acid recovery from the fermentation medium. On the other hand, L. pentosus cells were submitted to extraction process with PBS to evaluate the intracellular biosurfactants. In presence of vinification lees or corn steep liquid plus yeast extract, the extracted biosurfactants of L. pentosus reduced the superficial tension of PBS in 23.5 and 25.5 m N/m, respectively. No extracellular biosurfactants were observed.