The present invention relates to a yeast cell, in particular a recombinant yeast cell, the cell lacking enzymatic activity needed for the NADH-dependent glycerol synthesis or the cell having a reduced enzymatic activity with respect to the NADH-dependent glycerol synthesis compared to its corresponding wild-type yeast cell, the cell comprising one or more heterologous nucleic acid sequences encoding an NAD.sup.+-dependent acetylating acetaldehyde dehydrogenase (EC 1.2.1.10) activity. The invention further relates to the use of a cell according to the invention in the preparation of ethanol.

The disclosure discloses construction and application of an engineered strain of E. coli for producing malic acid by fixing CO.sub.2, and belongs to the field of fermentation. The engineered strain is obtained by performing genetic engineering transformation on Escherichia coli MG1655; the genetic engineering transformation includes knocking out a fumarate reductase gene, a fumarase gene, a lactate dehydrogenase gene and an alcohol dehydrogenase gene and freely overexpressing a formate dehydrogenase, an acetyl coenzyme A synthetase, an acylated acetaldehyde dehydrogenase, a formaldehyde lyase, a dihydroxyacetone kinase, a malic enzyme and a phosphite oxidoreductase to obtain a strain GH0407. The strain is used for producing malic acid by fermentation, anaerobic fermentation is performed for 72 hours with CO.sub.2 and glucose as a co-substrate, the production of malic acid reaches 39 g/L, the yield is 1.53 mol/mol, and accumulation of malic acid in the original strain is not achieved.

Provided are a genetically engineered strain for producing polylactic acid and a method for producing polylactic acid. The genome of the genetically engineered strain is integrated with a coding sequence of exogenous D-lactate dehydrogenase gene, a coding sequence of exogenous propionyl-CoA transferase gene, and a coding sequence of exogenous polyhydroxyalkanoate synthase gene, enabling the genetically engineered strain to express exogenous D-lactate dehydrogenase, exogenous propionyl-CoA transferase, and exogenous polyhydroxyalkanoate synthase. The method includes: providing the above genetically engineered strain of Synechococcus elongatus; introducing carbon dioxide and culturing the genetically engineered strain under light; and when a growth OD of the genetically engineered strain reaches the maximum, collecting and drying the genetically engineered strain, and recycling the polylactic acid in the strain.

The present disclosure relates to genetically engineered methanotrophic bacteria with the capability of growing on a multi-carbon substrate (e.g., glucose) as a primary or sole carbon source and methods for growing methanotrophic bacteria on the multi-carbon substrate.

The present invention belongs to the bioengineering field, and relates to a method for fermentation production of L-theanine by using an Escherichia coli genetically engineered bacterium. The engineered bacterium is obtained by serving a strain as an original strain, wherein the strain is obtained after performing a single copy of T7RNAP, a dual copy of gmas, xylR knockout, and sucCD knockout on an Escherichia coli W3110 genome, and by integrating genes xfp, pta, acs, gltA, and ppc, and knocking out ackA on the genome. The present invention has a high yield, and stable production performance; after 20-25 h, L-theanine has a titer of 75-80 g/L, and the yield is up to 52-55%. The fermentation broth is purified by membrane separation in combination with a cation-anion resin series technique. Moreover, the one-step crystallization yield is 72.3% and the L-theanine final product has a purity of 99%.

The present invention relates to Saccharomyces sp. capable of producing lactic acid with a decreased activity of pyruvate decarboxylase (PDC) and increased activities of aldehyde dehydrogenase (ALD) and acetyl-CoA synthetase (ACS), and a method of producing lactic acid from the culture medium obtained by culturing the microorganism.

The present invention relates to the provision of genetically modified fungal cells, such as yeast cells with an improved ability for producing different fatty acids and specifically fatty acid ethyl esters (FAEE), the main components of biodiesel. An increased in fatty acid production, and hence in FAEE, is obtained in the first place by expressing different heterologous polypeptides in combination with the down-regulation, attenuation, deletion or over-expression of specially selected genes, wherein said genes encode enzymes involved in the fatty acids synthesizing pathway, fatty acid consuming pathways, carbohydrate biosynthesis pathways or enzyme acting as wax ester transporters or a combination thereof. The methods and products of the invention would allow large-scale production of FAEE with carbohydrates as the only externally-supplied substrate.

Disclosed is a modified microorganism producing putrescine or ornithine, and a method for producing putrescine or ornithine using the same.

The present invention relates to Saccharomyces sp. capable of producing lactic acid with a decreased activity of pyruvate decarboxylase (PDC) and increased activities of aldehyde dehydrogenase (ALD) and acetyl-CoA synthetase (ACS), and a method of producing lactic acid from the culture medium obtained by culturing the microorganism.

The present disclosure relates to genetically engineered methanotrophic bacteria with the capability of growing on a multi-carbon substrate (e.g., glycerol) as a primary or sole carbon source and methods for growing methanotrophic bacteria on the multi-carbon substrate.