The present invention relates to novel nucleic acid sequences encoding bacterial xylose isomerases that upon transformation of a eukaryotic microbial host cell, such as yeast, to confer to the host cell the ability of isomerising xylose to xylulose. The nucleic acid sequences encode xylose isomerases that originate from bacteria such as Eubacterium sp., Clostridium cellulosi and others. The invention further relates to fermentation processes wherein the transformed host cells ferment a xylose-containing medium to produce ethanol or other fermentation products.

The present invention relates to novel nucleic acid sequences encoding bacterial xylose isomerases that upon transformation of a eukaryotic microbial host cell, such as yeast, to confer to the host cell the ability of isomerising xylose to xylulose. The nucleic acid sequences encode xylose isomerases that originate from bacteria such as Eubacterium sp., Clostridium cellulosi and others. The invention further relates to fermentation processes wherein the transformed host cells ferment a xylose-containing medium to produce ethanol or other fermentation products.

This document describes biochemical pathways for producing 7-aminoheptanoic acid using a β-ketoacyl synthase or a β-ketothiolase to form an N-acetyl-5-amino-3-oxopentanoyl-CoA intermediate. 7-aminoheptanoic acid can be enzymatically converted to pimelic acid, 7-hydroxyheptanoic acid, heptamethylenediamine or 1,7-heptanediol or corresponding salts thereof. This document also describes recombinant microorganisms producing 7-aminoheptanoic acid as well as pimelic acid, 7-hydroxyheptanoic acid, heptamethylenediamine and 1,7-heptanediol or corresponding salts thereof.

This document describes biochemical pathways for producing 7-aminoheptanoic acid using a β-ketoacyl synthase or a β-ketothiolase to form an N-acetyl-5-amino-3-oxopentanoyl-CoA intermediate. 7-aminoheptanoic acid can be enzymatically converted to pimelic acid, 7-hydroxyheptanoic acid, heptamethylenediamine or 1,7-heptanediol or corresponding salts thereof. This document also describes recombinant microorganisms producing 7-aminoheptanoic acid as well as pimelic acid, 7-hydroxyheptanoic acid, heptamethylenediamine and 1,7-heptanediol or corresponding salts thereof.

The aim of the invention is to provide a method for biotechnological production of carboxylic acids, in which the acid-forming micro-organisms are cultured in an unsterile manner in a submerged phase containing waste water containing all carbon and nutrient medium components necessary for the production of the carboxylic acid, which method avoids the disadvantages of known methods and enables high product concentrations and productivity while at the same time the resources of water and power are being conserved. This aim is achieved, according to the invention, in that micro-organisms are used that are cultured under unsterile conditions in a culture medium containing waste water with the addition of carbon-rich compounds.

The aim of the invention is to provide a method for biotechnological production of carboxylic acids, in which the acid-forming micro-organisms are cultured in an unsterile manner in a submerged phase containing waste water containing all carbon and nutrient medium components necessary for the production of the carboxylic acid, which method avoids the disadvantages of known methods and enables high product concentrations and productivity while at the same time the resources of water and power are being conserved. This aim is achieved, according to the invention, in that micro-organisms are used that are cultured under unsterile conditions in a culture medium containing waste water with the addition of carbon-rich compounds.

The present invention provides an acid-tolerant Saccharomyces cerevisiae strain and use thereof. By using exogenously added malic acid as a stress, an acid-tolerant mutant S. cerevisiae strain MTPfo-4 is obtained by directed evolution screening in the laboratory, which tolerates a minimum pH of 2.44. The mutant strain MTPfo-4, tolerant to multiple organic acids, has an increased tolerance to exogenous malic acid of up to 86.6 g/L. The mutant strain MTPfo-4 obtained is further identified. The mutant strain grows stably and well, and can tolerate a variety of organic acids (lactic acid, malic acid, succinic acid, fumaric acid, citric acid, gluconic acid, and tartaric acid). It also has a strong tolerance to inorganic acids (HCl and H.sub.3PO.sub.4). This is difficult to achieve in the existing research and reports of S. cerevisiae. The strain is intended to be used as an acid-tolerant chassis cell factory for producing various short-chain organic acids.

An acetyl-CoA producing microorganism obtained by imparting at least one enzymatic activity selected from the group consisting of malate thiokinase, malyl-CoA lyase, glyoxylate carboligase, 2-hydroxy-3-oxopropionate reductase, and hydroxypyruvate reductase, to a microorganism that does not have any of the following (a), (b), (c), (d) or (e): (a) a carbon dioxide fixation cycle including an enzymatic reaction from malonyl-CoA to malonate semialdehyde or 3-hydroxypropionate; (b) a carbon dioxide fixation cycle including an enzymatic reaction from acetyl-CoA and CO.sub.2 to pyruvate; (c) a carbon dioxide fixation cycle including an enzymatic reaction from crotonyl-CoA and CO.sub.2 to ethylmalonyl-CoA or glutaconyl-CoA; (d) a carbon dioxide fixation cycle including an enzymatic reaction from CO.sub.2 to formate; or (e) at least one selected from the group consisting of malate thiokinase and malyl-CoA lyase.

An acetyl-CoA producing microorganism obtained by imparting at least one enzymatic activity selected from the group consisting of malate thiokinase, malyl-CoA lyase, glyoxylate carboligase, 2-hydroxy-3-oxopropionate reductase, and hydroxypyruvate reductase, to a microorganism that does not have any of the following (a), (b), (c), (d) or (e): (a) a carbon dioxide fixation cycle including an enzymatic reaction from malonyl-CoA to malonate semialdehyde or 3-hydroxypropionate; (b) a carbon dioxide fixation cycle including an enzymatic reaction from acetyl-CoA and CO.sub.2 to pyruvate; (c) a carbon dioxide fixation cycle including an enzymatic reaction from crotonyl-CoA and CO.sub.2 to ethylmalonyl-CoA or glutaconyl-CoA; (d) a carbon dioxide fixation cycle including an enzymatic reaction from CO.sub.2 to formate; or (e) at least one selected from the group consisting of malate thiokinase and malyl-CoA lyase.

The present invention provides a method for producing an alcohol comprising: (a) admixing a tripeptidyl peptidase, predominantly having exopeptidase activity, with a feedstock or a fraction thereof before, during or after fermentation of said feedstock or a fraction thereof; and (b) recovering an alcohol. Also provided are uses of a tripeptidyl peptidase and by-products of alcohol production obtainable by the method of the invention.