| Abstract [eng] |
Introduction Bioproduction of optically pure lactic acid (LA) has roused interest in the recent years due to its potential application in a wide range of fields, and there is a significant interest to further development of sustainable and cost-effective process. However, the efficient utilization of agro-industrial wastes for LA production still causes considerable challenges. The biotechnological LA production within the targeted cost still required the development of high-performance LA-producing microorganisms and the lowering of the costs of raw materials and fermentation process. Cheap biomass, such as starchy and cellulosic agricultural residues or by-products from the food industry, has a potential for the cost-effective production of LA, but raw materials also should have a high production rate and yield without by-product formation and the ability to be fermented with low pretreatment (Wee et al., 2006). Whereas the LA made by fermentation route refers optically active, consequently a suitable microorganism could selectively produce dextro (levo)-rotation enantiomers, and the greatest demand is for the l-LA isomer (Sheldon, 2011). Targeted conversion of starchy substrates to LA can be performed using the amylolytic microorganisms (Gonzalez et al., 2007). Fungi species from Rhizopus, such as Rhizopus oryzae and Rhizopus arrhizus, excreate amylolytic activity that enables to convert starch directly into l-LA in the presence of oxygen (Hofvendahl and Hahn-Hägerdal, 2000). However, LA-producing microorganisms, including the fungus R. oryzae, have low productivity depended on the low reaction rate caused by mass transfer limitation (Okano et al., 2010). Most of the world’s commercial l-LA is produced by the fermentation of carbohydrates using homolactic microbes such as a variety of modified or developed strains of the genus Lactobacilli (Naveena et al., 2005; Ohkouchi and Inoue, 2006). [...]. |
