The present invention relates to a recombinant microorganism having the ability to produce poly(lactate-co-glycolate) and its copolymers from xylose, and more particularly to a recombinant microorganism having the ability to produce poly(lactate-co-glycolate) and its copolymers without having to supply a glycolate precursor from an external source, and a method of producing a poly(lactate-co-glycolate) copolymers using the same.

The present invention relates to a method for constructing a recombinant bacterium with high production of ?-elemene and germacrene A. Firstly, ?-elemene and germacrene A are synthesized from scratch through the screening of germacrene A synthase and the overexpression of the mevalonate pathway; then, the availability of acetyl-CoA, pyruvate, and glyceraldehyde-3-phosphate in the farnesyl diphosphate pathway is ensured by deleting competing pathways in the central carbon metabolism; next, the present invention uses lycopene color as a high-throughput screening method and obtains an optimized NSY305N through error-prone PCR. Finally, in shake flasks, strain ?-EL-4 constructed through key pathway enzymes, efflux engineering, and translation engineering produced 1161.09 mg/L of ?-elemene and 852.36 mg/L of germacrene A, which is the highest reported yield at shake flask level. In 4-L fed-batch fermentation, the production of ?-elemene and germacrene A reached 3.52 g/L and 2.13 g/L, respectively.

The present disclosure provides, in various aspects, engineered alcohol tolerant yeast and methods of producing high concentrations of biofuels and bioplastics from toxic feedstocks.

The present invention discloses a bacterium and an obtaining method and application thereof. The bacterium has a property of coproducing 1,3-propanediol and D-lactic acid. Further, the bacterium is Klebsiella oxytoca, including Klebsiella oxytoca PDL-5 CCTCC M 2016185. The obtaining method of the bacterium may be to obtain the bacterium by directly screening wild bacteria that satisfy conditions from the environment or performing gene engineering modification to wild bacteria. The present invention has the advantages that the bacteria can coproduce 1,3-propanediol and D-lactic acid through fermentation, the molar conversion rate and the concentration of the two products are very high, the types of byproducts are few, the concentration is low, the product extraction process is simplified, the high-efficiency biological production of 1,3-propanediol and D-lactic acid can be realized, and the industrial application prospect is very great.

The present invention relates to a method for preparing a D-lactic acid-producing strain modified to inhibit L-lactate dehydrogenase (L-LDH) activity and to introduce D-lactate dehydrogenase (D-LDH) activity in an L-lactic acid-producing strain, a mutated D-lactic acid-producing strain prepared by the above method, and a method for producing D-lactic acid including the steps of culturing the strain and recovering D-lactic acid from the culture media.

The present application relates to a microorganism of the genus Saccharomyces producing lactic acid and a method for preparing lactic acid using the same. More specifically, the present application relates to a microorganism of the genus Saccharomyces producing lactic acid, wherein the microorganism is modified to weaken or inactivate the activity of pyruvate decarboxylase (PDC) compared to its endogenous activity, to introduce the activity of ATP-citrate lyase (ACL), and to enhance pyruvate biosynthetic pathway compared to its endogenous biosynthetic pathway, and a method for producing lactic acid using the microorganism.

The present invention provides a genetically modified lactic acid bacterium capable of producing diacetyl under aerobic conditions. Additionally the invention provides a method for producing diacetyl using the genetically modified lactic acid bacterium under aerobic conditions in the presence of a source of iron-containing porphyrin and a metal ion selected from Fe.sup.3+, Fe.sup.2+ and Cu2+. The lactic acid bacterium is genetically modified by deletion of those genes in its genome that encode polypeptides having lactate dehydrogenase (E.C 1.1.1.27/E.C.1.1.1.28); -acetolactate decarboxylase (E.C 4.1.1.5); water-forming NADH oxidase (E.C. 1.6.3.4); phosphotransacetylase (E.C.2.3.1.8) activity; and optionally devoid of or deleted for genes encoding polypeptides having diacetyl reductase ((R)-acetoin forming; EC: 1.1.1.303); D-acetoin reductase; butanediol dehydrogenase ((R,R)-butane-2,3-diol forming; E.C. 1.1.1.4/1.1.1.-) and alcohol dehydrogenase (E.C. 1.2.1.10) activity. The invention provides for use of the genetically modified lactic acid bacterium for the production of diacetyl and a food product.

The invention relates to a recombinant cell, preferably a yeast cell comprising one or more genes coding for an enzyme having glycerol dehydrogenase activity, one or more genes coding dihydroxyacetone kinase (E.C. 2.7.1.28 and/or E.C. 2.7.1.29); one or more genes coding for an enzyme in an acetyl-CoA-production pathway and one or more genes coding for an enzyme having at least NAD.sup.+ dependent acetylating acetaldehyde dehydrogenase activity (EC 1.2.1.10 or EC 1.1.1.2), and optionally one or more genes coding for a glycerol transporter. This cell can be used for the production of ethanol and advantageously produces little or no glycerol.

A method of screening a microorganism having a mutant lactate dehydrogenase with increased activity, a mutant lactate dehydrogenase polypeptide, a polynucleotide and vector encoding same, and a microorganism that expresses the lactate dehydrogenase mutant, and a method of producing lactate using the microorganism.

Provided is an acid-tolerant yeast cell, a method of producing an organic acid by using the yeast cell, and a method of producing the yeast cell resistant to acid.