We investigated metabolic engineering of fermentation pathways in Escherichia coli for production of optically pure Dor L-lactate. Several pta mutant strains were examined, and a pta mutant of E. coli RR1 which was deficient in the phosphotransacetylase of the Pta-AckA pathway was found to metabolize glucose to D-lactate and to produce a small amount of succinate by-product under anaerobic cond...

We investigated metabolic engineering of fermentation pathways in Escherichia coli for production of optically pure D- or L-lactate. Several pta mutant strains were examined, and a pta mutant of E. coli RR1 which was deficient in the phosphotransacetylase of the Pta-AckA pathway was found to metabolize glucose to D-lactate and to produce a small amount of succinate by-product under anaerobic co...

The aim of this work was to discover the extent of interference by phosphoenolpyruvate (PEP) phosphatase in spectrophotometric assays of PEP carboxylase (EC 4.1.1.31) in crude extracts of plant organs. The presence of PEP phosphatase and lactate dehydrogenase (EC 1.1.1.27) in extracts leads to PEP-dependent NADH oxidation that is independent of PEP carboxylase activity, and hence to overestimat...

The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory growth conditions. Under anoxic growth conditions ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates its target operons. The anaerobic metabolite D-lactate has been shown to stimulate th...

Analysis of nondeproteinized samples with an enzymatic method to determine D-lactate indicated interferences. The presence of L-lactate dehydrogenase (LD) and L-lactate in the sample led to underestimation of D-lactate content when a sample blank was processed and overestimation when it was omitted. We proved that this interference is not due to lack of D-LD stereospecificity. Moreover, assessm...

The traditional CaCO3-based fermentation process generates huge amount of insoluble CaSO4 waste. To solve this problem, we have developed an efficient and green D-lactic acid fermentation process by using ammonia as neutralizer. The 106.7 g/L of D-lactic acid production and 0.89 g per g of consumed sugar were obtained by Sporolactobacillus inulinus CASD with a high optical purity of 99.7% by ad...

Five lactate dehydrogenase (LD; L-lactate:NAD oxidoreductase, EC 1.1.127) isoenzymes are demonstrated by electrophoresis in normal human serum. Altered activities of these isoenzymes have been associated with pathological conditions, so that their determination has become a useful diagnostic aid. Abnormal LD-isoenzyme patterns with one and two extra isoenzyme bands have been reported in serum s...

The nonallosteric and allosteric L-lactate dehydrogenases of Lactobacillus pentosus and L. casei, respectively, exhibited broad substrate specificities, giving virtually the same maximal reaction velocity and substrate K(m) values for pyruvate and oxaloacetate. Replacement of Pro101 with Asn reduced the activity of the L. pentosus enzyme toward these alternative substrates to a greater extent t...

The haemolymph of the crayfish Austropotamobius pallipes exhibits a high affinity for oxygen (P50 = 2-7 Torr at pH7-9 and 15°C) and a modest Bohr effect (<p = —0-455). The affinity of haemolymph dialysed against a crayfish Ringer was lower with a P50 value of 6 4 Torr at the same temperature and pH. The oxygen affinity of the dialysed haemolymph can be increased markedly by increased concentrat...

As an important method for building blocks synthesis, whole cell biocatalysis is hindered by some shortcomings such as unpredictability of reactions, utilization of opportunistic pathogen, and side reactions. Due to its biological and extensively studied genetic background, Pseudomonas putida KT2440 is viewed as a promising host for construction of efficient biocatalysts. After analysis and rec...