A recombinant yeast cell functionally expressing: a) a nucleic acid sequence encoding a protein comprising phospho-ketolase (PKL) activity (EC 4.1.2.9 or EC 4.1.2.22) and/or a nucleic acid sequence encoding a protein having phosphotransacetylase (PTA) activity (EC 2.3.1.8) and/or a nucleic acid sequence encoding a protein having acetate kinase (ACK) activity (EC 2.7.2.12); and/or) a nucleic acid sequence encoding a protein having transketolase activity (EC 2.2.1.1), wherein the expression of the nucleic acid sequence encoding the protein having transketolase activity is under control of a promoter (the TKL promoter), which TKL promoter has an anaerobic/aerobic expression ratio for the transketolase of (2) or more.

Provided are a method for constructing a lactic acid-producing strain, a lactic acid-producing strain and use thereof. The method for constructing lactic acid-producing strains is characterized by genetically engineering a starting strain to increase lactic acid production, wherein the engineering includes: 1) introducing a lactic acid synthesis pathway; 2) optimizing the lactic acid synthesis pathway; and 3) inhibiting by-product synthesis pathways.

The present invention relates to preparation of key drug intermediate, L-2-amino butyric acid (L-2-ABA) by a method of cell free system and biotransformation using genetically engineered strains from easily available economic substrates like citramalate or citraconate and enzymes like LeuCD, LeuB and ValDH or IlvE.

Described is a recombinant organism or microorganism which is capable of enzymatically converting acetyl-CoA into isobutene, (A) wherein in said organism or microorganism: (i) acetyl-CoA is enzymatically converted into acetoacetyl-CoA, (ii) acetoacetyl-CoA is enzymatically converted into 3-hydroxy-3-methylglutaryl-CoA, (iii) 3-hydroxy-3-methylglutaryl-CoA is enzymatically converted into 3-methylglutaconyl-CoA, (iv) 3-methylglutaconyl-CoA is enzymatically converted into 3-methylcrotonyl-CoA, and (v) wherein said 3-methylcrotonyl-CoA is converted into isobutene by: (a) enzymatically converting 3-methylcrotonyl-CoA into 3-methylcrotonic acid which is then further enzymatically converted into said isobutene; or (b) enzymatically converting 3-methylcrotonyl-CoA into 3-hydroxy-3-methylbutyryl-CoA which is then further enzymatically converted into 3-hydroxy-3-methylbutyric acid which is then further enzymatically converted into 3-phosphonoxy-3-methylbutyric acid which is then further enzymatically converted into said isobutene; (B) wherein said recombinant organism or microorganism has an increased pool of coenzyme A (CoA) over the organism or microorganism from which it is derived due to: (i) an increased uptake of pantothenate; and/or (ii) an increased conversion of pantothenate into CoA. Moreover, described is the use of such a recombinant organism or microorganism for the production of isobutene. Further, described is a method for the production of isobutene by culturing such a recombinant organism or microorganism in a suitable culture medium under suitable conditions.

The present specification relates to a microorganism into which a GPD gene, a GPP gene, and dhaB, gdrAB, aldH and/or yqhD genes are introduced, and/or use thereof, the microorganism being capable of simultaneously producing 1,3-PDO and 3-HP.