Metabolic engineering of Klebsiella oxytoca M5a1 to produce optically pure D-lactate in mineral salts medium.
Klebsiella oxytoca strains were constructed to produce optical pure d-lactate by pH-controlled batch fermentation in mineral salts medium. The alcohol dehydrogenase gene, adhE, and the phospho-transacetylase/acetate kinase A genes, pta-ackA, were deleted from the wild type. KMS002 (ΔadhE) and KMS004 (ΔadhE Δpta-ackA) exhibited d-lactate production as a primary pathway for the regeneration of NAD(+). Both strains produced 11-13 g/L of d-lactate in medium containing 2% (w/v) glucose with yields of 0.64-0.71 g/g glucose used. In sugarcane molasses, KMS002 and KMS004 produced 22-24 g/L of d-lactate with yields of 0.80-0.87 g/g total sugars utilized. Both strains also utilized maltodextrin derived from cassava starch and produced d-lactate at a concentration of 33-34 g/L with yields of 0.91-0.92 g/g maltodextrin utilized. These d-lactate yields are higher than those reported for engineered E. coli strains.
Metabolic Engineering Research Unit, School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, 111 University Avenue, Suranaree Sub-District, Muang District, Nakhon Ratchasima 30000, Thailand.
Maytawadee
M
Sangproo
Pattharasedthi
P
Polyiam
Sirima Suvarnakuta
SS
Jantama
Sunthorn
S
Kanchanatawee
Kaemwich
K
Jantama
D000084:Acetate Kinase / Q000235:genetics*; D000426:Alcohol Dehydrogenase / Q000235:genetics*; D020868:Gene Silencing; D041121:Klebsiella oxytoca / Q000502:physiology*; D019344:Lactic Acid / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D060847:Metabolic Engineering / Q000379:methods*; D008903:Minerals / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism*; D012492:Salts / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism*
D008903:Minerals; D011134:Polysaccharides; D012492:Salts; D019344:Lactic Acid; D013395:Sucrose; C008315:maltodextrin; D000426:Alcohol Dehydrogenase; D000084:Acetate Kinase