Selection of strains from Lactobacillus sp. for lactic acid fermentation of thin stillage

Abstract

Bioethanol produced by fermentation of biomass, such as sugar, starch, or lignocellulosic materials, is one of the most important renewable energy resources today. Beside the bioethanol, considerable amounts of by-products such as carbon dioxide, solid and liquid stillage are formed during the fermentation. Their further utilization could significantly increase the economy of bioethanol production. It is estimated that per 1hl of the produced bioethanol, approximately 13 hl of liquid thin stillage is formed. It contains high concentrations of organic and inorganic substances and must be pretreated before its disposal to water flows. In addition to recirculation of thin stillage and its reuse, production of soil fertilizers and various types of animal feed, the thin stillage can be used as a substrate for anaerobic fermentation for the production of butanol or especially lactic acid. Lactic acid has versatile application not only in food, pharmaceutical, leather and textile industries, but also as a chemical feedstock for the production of base chemicals (propylene glycol, propylene oxide, acrylic acid, acrylate esters, lactate ester and etc) or for the preparation of biodegradable polymers (poly lactic acid), medical sutures, and green solvents. The aim of this work was to select appropriate species for lactic acid fermentation of the corn thin stillage which is an inexpensive renewable substrate.