BIOSYNTHESIS OF LACTIC ACID VIA FERMENTATION OF WHEAT STRAW AUTOHYDROLYSIS PRODUCTS

Lactic acid is commonly used in food, chemical, pharmaceutical industry and other fields. It is expensive to produce it from chemically pure carbohydrates. The sugars isolated from lignocellulosic material could be an attractive alternative primary product to obtain lactic acid. In this study, the feasibility of wheat straw autohydrolysis products as a substrate for lactic fermentation was evaluated so far as they are characterized by high content of sugars. We used Lactobacillus plantarum VKM B-578 as the lactic acid producer. The sugars isolated from wheat straw under the subcritical conditions could be used as a substrate for lactic acid biosynthesis. Both initial fraction and their hydrolyzates inhibited fermentation and lactic acid yield when used as the only source of carbon. The largest yield of lactic acid was found to be 2.4 g/l or 21% of theoretically possible under the experiment condition. Therefore the fermentation inhibitors should be detected and theirs effect should be minimized, in addition, optimal conditions including the fraction dosage and the fermentation parameters should be ascertained.