Abstract
In this work is presented a process with high lactic acid production as well as high sugar conversion and low by-products formation. The microorganism Lactobacillus plantarum uses preferably 6-carbon sugars. However, the xylose consumption occurs since the hexose concentration is not high. Lb. plantarum was shown to have a capacity for lactic acid production from cellulosic and hemicellulosic hydrolysates without detoxification. The results were similar to that using glucose, which is the source of carbon currently used by the lactic acid industry.
Lactic acid is an organic acid with a hydroxyl and an acid functional group. It has an asymmetric carbon and it naturally occurs as two optical isomers, D and L lactic acid. Crystallinity and many other important physical properties such as rate of degradation, melting point and boiling point are controlled by the ratio of enantiomers used. Lactic acid production by fermentation has several advantages when compared to chemical synthesis, such as low temperatures, low energy consumption, better environmental concerns and high purity. Furthermore, by fermentation it is possible to obtain the optically pure lactic acid, while by chemical synthesis only the racemic mixture can be produced. Despite the wide variety of feedstock tested for the lactic acid production most of them have problems with price, seasonality, continuous availability for large- scale production, fermentation rate, the amount of contaminants present, yields of lactic acid, formation of by- products, location of lactic acid production plant due to both availability as logistics of transportation and use of it. Trying to find substrates that overcome some of these barriers, in this work is proposed the use of molasses from sugar industry, pentose and hexose from enzymatic hydrolysis of sugarcane bagasse aiming to produce lactic acid.
