Recombinant yeast cells contain a reductive TCA pathway from phosphoenolpyruvate or pyruvate to succinate. At least one metabolic step in the pathway includes a reaction of NADPH to produce NADP+. The yeast cell contains at least one exogenous NADPH-dependent gene in the pathway from phosphoenolpyruvate or pyruvate to succinate, preferably an NADPH-dependent malate dehydrogensase or fumarate reducase gene (or both).

This invention relates to the metabolic evolution of a microbial organism previously optimized for producing an organic acid in commercially significant quantities under fermentative conditions using a hexose sugar as sole source of carbon in a minimal mineral medium. As a result of this metabolic evolution, the microbial organism acquires the ability to use pentose sugars derived from cellulosic materials for its growth while retaining the original growth kinetics, the rate of organic acid production and the ability to use hexose sugars as a source of carbon. This invention also discloses the genetic change in the microorganism that confers the ability to use both the hexose and pentose sugars simultaneously in the production of commercially significant quantities of organic acids.

Provided are an engineered strain for synthesizing a dibasic organic acid and preparation and application of same. The engineered strain introduces or up-regulates expression of a positive regulator gene for synthesis of a dibasic organic acid, and/or down-regulates expression of a negative regulator gene for synthesis of a dibasic organic acid, as compared with the origin strain of the engineered strain, the producing capability for producing the dibasic organic acid is improved. The dibasic organic acid comprises malic acid, succinic acid, fumaric acid, oxaloacetic acid, glutaric acid, and adipic acid; the expression product of the positive regulator gene comprises aspartate aminotransferase, glutamic acid-aspartate transporter, C4-dicarboxylic acid transporter, pyruvate carboxylase and malate dehydrogenase, glucose transporter; the expression product of the negative regulatory gene comprises succinyl-CoA synthase, and malic acid-alpha ketoglutarate transporter, and the original strain comprises myceliophthora thermophila, thielavia terrestris, aspergillus, and rhizopus.

Yeast cells having a reductive TCA pathway from pyruvate or phosphoenolpyruvate to succinate, and which include at least one exogenous gene overexpressing an enzyme in that pathway, further contain an exogenous transhydrogenase gene.

The present invention relates to a modified polynucleotide encoding aspartate kinase (EC:2.7.2.4; hereinafter, referred to as LysC), transketolase (EC:2.2.1.1; hereinafter, referred to as Tkt) or pyruvate carboxylase (EC:6.4.1.1; hereinafter, referred to as Pyc), in which the initiation codon is substituted with ATG, a vector including the same, a microorganism transformed with the vector, and a method for producing L-lysine using the same.

Described are genetically engineered C1-utilizing bacteria for the preparation of dicarboxylic acids, e.g. succinic acid. For instance, the bacteria comprise a mutation in a gene encoding a tricarboxylic acid cycle (TCA) succinate dehydrogenase (Sdh), preferably a mutation which inactivates or reduces Sdh's activity. Processes for the production of the modified bacteria as well as their use in the preparation of succinic acid on a C1-compound as carbon source are also discussed.

A genetically modified Saccharomyces cerevisiae including an active fermentation pathway producing 3-HP expresses an exogenous gene expressing the aminotransferase YhxA from Bacillus cereus AH1272 catalyzing a transamination reaction between beta-alanine and pyruvate to produce malonate semialdehyde. The yeast may also express a 3-hydroxyisobutyrate dehydrogenase (HIBADH) and a 3-hydroxypropanoate dehydrogenase (3-HPDH) and aspartate 1-decarboxylase. Additionally the yeast may express pyruvate carboxylase and aspartate aminotransferase.

The invention provides an effective method for improving N-acetylglucosamine (GlcNAc) production by engineered B. subtilis Deletion of phosphoenolpyruvate carboxykinase encoding gene pckA and encoding pyruvate kinase gene pyK in recombinant GlcNAc-producing strain BSGNK-PxylA-glmS-P43-GNA1 (BSGNK) is first performed to enhance GlcNAc production, followed by overexpression of pyruvate carboxylase encoding gene pycA for facilitating cell growth. Finally, the GlcNAc production of the recombinant strain BPTS3 reached to 11.3 g/L, which was 1.84-fold of BSGNK. This method can be used for improve cellular property of engineered B. subtilis for GlcNAc production, which can be further applied to industrial production of GlcNAc.

The present invention provides a genetically modified malic acid producing yeast strain, wherein the strain has or has enhanced malate transport protein activity and has or has enhanced NADPH-dependent malate dehydrogenase (EC 1.1.1.82) activity, optionally also has or has enhanced at least one of the following activities: (i) pyruvate carboxylase (EC 6.4.1.1) activity, (ii) phosphoenolpyruvate carboxykinase (EC 4.1.1.49) activity, (iii) phosphoenolpyruvate carboxylase activity, and (iv) biotin transport protein activity; and a preparation method thereof, a method for producing L-malic acid using the same, and use thereof.

Provided a genetically modified yeast strain for producing succinic acid, which strain has the activity or an enhanced activity of an NADPH-dependent malate dehydrogenase (EC 1.1.1.82), and optionally also has the activity or an enhanced activity of at least one of the following: (i) soluble fumarate reductase (EC 4.2.1.2), (ii) a pyruvate carboxylase (EC 6.4.1.1), (iii) a fumarase (EC 4.2.1.2), and (iv) succinate transport protein; and a preparation method therefor, a method for producing succinic acid using same, and the use thereof.