Direct fermentation of Jerusalem artichoke tuber powder for production of l-lactic acid and d-lactic acid by metabolically engineered Kluyveromyces marxianus

Publication date: Available online 5 December 2017 Source:Journal of Biotechnology Author(s): Jung-Hoon Bae, Hyun-Jin Kim, Mi-Jin Kim, Bong Hyun Sung, Jae-Heung Jeon, Hyun-Soon Kim, Yong-Su Jin, Dae-Hyuk Kweon, Jung-Hoon Sohn An efficient production system for optically pure l- and d-lactic acid (LA) from Jerusalem artichoke tuber powder (JAP) was developed by metabolic engineering of Kluyveromyces marxianus. To construct LA-producing strains, the ethanol fermentation pathway of K. marxianus was redirected to LA production by disruption of KmPDC1 and expression of l- and d-lactate dehydrogenase (LDH) genes derived from Lactobacillus plantarum under the control of the K. marxianus translation elongation factor 1α promoter. To further increase the LA titer, the l-LA and d-LA consumption pathway of host strains was blocked by deletion of the oxidative LDH genes KmCYB2 and KmDLD1. The recombinant strains produced 130g/L l-LA and 122g/L d-LA by direct fermentation from 230g/L JAP containing 140g/L inulin, without pretreatment or nutrient supplementation. The conversion efficiency and optical purity were >95% and >99%, respectively. This system using JAP and the inulin-assimilating yeast K. marxianus could lead to a cost-effective process for the production of LA.
Source: Journal of Biotechnology - Category: Biotechnology Source Type: research