Method for producing medium chain diol

This application is a National Stage Application of PCT/KR2016/012170, filed 27 Oct. 2016, which claims benefit of Serial No. 10-2016-0141017, filed 27 Oct. 2016 in Korea and Serial No. 10-2015-0149251, filed 27 Oct. 2015 in Korea and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above disclosed applications.

The present invention relates to a method for producing a medium chain diol, and more particularly, to a method for producing a medium chain diol from a fatty acid-derived alcohol or alkane by culturing a recombinant microorganism from which fatty alcohol dehydrogenase and/or fatty alcohol oxidase genes in an ω-oxidative metabolism pathway are deleted, a fatty aldehyde dehydrogenase gene is optionally deleted, and β-oxidative metabolism pathway-related genes are also deleted.

Bioplatform compounds are produced through biological or chemical conversion on the basis of biomass-derived raw materials, and have been used for synthesis of polymeric monomers, new materials, and the like.

Among the bioplatform compounds, a medium chain diol is a material used as a monomer for polyesters. In this case, the polyesters have been used for various applications including fibers, films, and combinations thereof due to their excellent properties. For example, the polyethylene terephthalate obtained through the polycondensation of terephthalic acid with ethylene glycol has been used for many applications due to excellent physical properties such as mechanical strength, chemical properties, and the like, and has been mass-produced as a synthetic fiber most suitable for clothing all over the world. Also, the market for polytrimethylene terephthalate prepared using 1,3-propanediol and terephthalic acid as raw materials tends to increase with the recent development of inexpensive methods of synthesizing 1,3-propanediol. Thus, the polytrimethylene terephthalate is expected to be employed for clothing applications requiring the soft texture because it has polymeric characteristics such as excellent elastic recovery percentage of elongation and low Young's modulus. In addition, the biomass resource-derived polyesters have come into the spotlight for fear of the rising price and depletion of petroleum resources.

Production of medium chain diols may be carried out using biological methods through chemical synthesis or microbial fermentation. In this case, the use of such biological methods requires the development of novel strains and the optimization of fermentation processes using metabolic engineering technology.

In the prior art, a microorganism which harbors a β-oxidative metabolism pathway as well as an ω-oxidative metabolism pathway may be used as the strain capable of producing a medium chain diol. For example, it is known that the strains such as Klebsiella oxytoca, Klebsiella pneumoniae, Aerobacter aerogenes , recombinant Saccharomyces cerevisiae , and the like may produce 2,3-butanediol with high yield and high productivity (Korean Patent Publication Nos. 10-2012-0107021, 10-2012-0128776, and 10-2015-0068581). However, because some of these microorganisms are classified into pathogenic microorganisms, they have limitations in terms of safety and industrialization. Also, because the medium chain diols correspond to intermediate products in the ω-oxidative metabolism pathway, the medium chain diols have a problem in that the medium chain diols may not be produced with high yield when they are produced using the microorganisms.

Technical Problem

Therefore, it is an object of the present invention to provide a recombinant microorganism from which fatty alcohol dehydrogenase and/or fatty alcohol oxidase-related genes in an ω-oxidative metabolism pathway are deleted, a fatty aldehyde dehydrogenase gene is optionally deleted, and β-oxidative metabolism pathway-related genes are also deleted, and a method of producing a medium chain diol from a fatty acid-derived alcohol or alkane by culturing the recombinant microorganism.

Technical Solution

To solve the above problems, according to an aspect of the present invention, there is provided a recombinant microorganism from which one or more genes selected from the group consisting of fatty alcohol dehydrogenase and fatty alcohol oxidase genes in an ω-oxidative metabolism pathway are deleted, a fatty aldehyde dehydrogenase gene is optionally deleted, and β-oxidative metabolism pathway-related genes are also deleted.

According to an embodiment of the present invention, the fatty alcohol dehydrogenase gene, the fatty alcohol oxidase gene, the fatty aldehyde dehydrogenase gene, and the β-oxidative metabolism pathway-related genes may be deleted from all homologous genes present in the microorganism, but the present invention is not limited thereto. According to another embodiment of the present invention, the fatty alcohol dehydrogenase gene, the fatty alcohol oxidase gene, the fatty aldehyde dehydrogenase gene, and the β-oxidative metabolism pathway-related genes may be deleted from some of the homologous genes present in the corresponding microorganism, but the present invention is not limited thereto.

According to an embodiment of the present invention, the fatty alcohol dehydrogenase gene may be selected from the group consisting of ADH1, ADH2, ADH3, ADH4, ADH5, ADH6, ADH7, ADH8, and FADH genes, but the present invention is not limited thereto. According to another embodiment of the present invention, the fatty alcohol oxidase gene may be an FAO gene, but the present invention is not limited thereto. According to still another embodiment of the present invention, the fatty aldehyde dehydrogenase gene may be a gene selected from the group consisting of FALDH1, FALDH2, FALDH3, and FALDH4 genes, but the present invention is not limited thereto.

According to an embodiment of the present invention, the β-oxidative metabolism pathway-related genes may be an acyl-CoA oxidase gene, but the present invention is not limited thereto. According to preferred embodiments of the present invention, the acyl-CoA oxidase gene may be selected from the group consisting of ACO1, ACO2, ACO3, ACO4, ACO5, and ACO6 genes, but the present invention is not limited thereto.

According to an embodiment of the present invention, the microorganism may be a yeast or Escherichia coli , but the present invention is not limited thereto. According to preferred embodiments of the present invention, the yeast may be selected from the group of the yeast consisting of Yarrowia sp., Saccharomyces sp., Pichia sp., and Candida sp., but the present invention is not limited thereto. According to other preferred embodiments of the present invention, the Yarrowia sp. yeast may be Yarrowia lipolytica , but the present invention is not limited thereto.

According to another aspect of the present invention, there is provided a method for producing a medium chain diol, which comprises (1) preparing a recombinant microorganism from which one or more genes selected from the group consisting of fatty alcohol dehydrogenase and fatty alcohol oxidase genes in an ω-oxidative metabolism pathway are deleted, a fatty aldehyde dehydrogenase gene is optionally deleted, and β-oxidative metabolism pathway-related genes are also deleted; and (2) treating the recombinant microorganism with a substrate to culture the recombinant microorganism.

According to an embodiment of the present invention, the substrate may be selected from the group consisting of a fatty acid-derived alcohol and alkane, but the present invention is not limited thereto. According to preferred embodiments of the present invention, each of the fatty acid-derived alcohol and alkane and the medium chain diol may have 5 to 30 carbon atoms, preferably 6 to 20 carbon atoms, and more preferably 8 to 16 carbon atoms, but the present invention is not limited thereto. According to other preferred embodiments of the present invention, the alkane may be dodecane, but the present invention is not limited thereto. According to still other preferred embodiments of the present invention, the medium chain diol may be 1,12-dodecanediol, but the present invention is not limited thereto.

Advantageous Effects

Because fatty alcohol dehydrogenase and/or fatty alcohol oxidase genes in an ω-oxidative metabolism pathway are deleted, a fatty aldehyde dehydrogenase gene is optionally deleted, and β-oxidative metabolism pathway-related genes are also deleted from a recombinant microorganism according to the present invention, the recombinant microorganism can produce medium chain diols with high yield by preventing further oxidation and β-oxidative metabolism of fatty alcohols.

FIG. 1 is a diagram showing types of products and related enzymes associated with ω-oxidative and β-oxidative metabolism reactions.

FIG. 2 is a diagram schematically showing a process of preparing a recombinant microorganism of the present invention from which fatty alcohol dehydrogenase, fatty alcohol oxidase and fatty aldehyde dehydrogenase genes associated with ω-oxidation and an acyl-CoA oxidase gene associated with β-oxidation are deleted.

FIG. 3 is a diagram schematically showing a vector containing an ura3 gene to be used as a selective marker for gene knockout to modify a strain, and a pop-out region for deleting the ura3 gene after insertion of a knock-out cassette.

FIG. 4 is a schematic diagram showing a process of constructing a knock-out cassette used to prepare a transformant microorganism according to the present invention.

FIG. 5 is a graph illustrating types of knock-out genes in the transformant microorganism according to the present invention.

FIG. 6 is a graph illustrating an amount of a medium chain diol produced from the alkane substrate, using the transformant microorganism according to the present invention.

FIG. 7 is a graph illustrating an amount of the medium chain diol produced from the alkane substrate, when an Y4-20 strain of the present invention is cultured in a flask.

FIG. 8 shows the GC/MS data showing that the medium chain diol is produced the alkane substrate in the Y4-20 strain according to the present invention.

The present invention provides a recombinant microorganism from which one or more genes selected from the group consisting of fatty alcohol dehydrogenase and fatty alcohol oxidase genes in an ω-oxidative metabolism pathway are deleted, a fatty aldehyde dehydrogenase gene is optionally deleted, and β-oxidative metabolism pathway-related genes are also deleted.

In the present invention, the term “ω-oxidation” refers to a metabolic process in which the terminal methyl group of a fatty acid is oxidized to form dicarboxylic acid, and the term “β-oxidation” refers to a metabolic process in which a carbon atom at the β-position in a carboxyl group is oxidized to release acetyl-CoA, whereby fatty acids are gradually decomposed to form fatty acids whose number of carbon atoms is reduced by two. The concept of the ω- and β-oxidations and the enzymes involved in such metabolic processes are widely known to persons having ordinary skill in the field of biochemistry. For example, when a fatty acid is used as the substrate for ω-oxidation, an ω-hydroxy fatty acid is first produced by means of an action of cytochrome P450 and an NADPH-cytochrome P450 reductase. Then, the ω-hydroxy fatty acid is converted into ω-aldehyde fatty acid by an action of a fatty alcohol dehydrogenase and a fatty alcohol oxidase, and the ω-aldehyde fatty acid is converted into dicarboxylic acid by an action of a fatty aldehyde dehydrogenase. Also, for the β-oxidation, a fatty acid whose number of carbon atoms is reduced by two is produced by an acyl-CoA oxidase (see FIG. 1 ).

According to an embodiment of the present invention, the fatty alcohol dehydrogenase and fatty alcohol oxidase genes and the fatty aldehyde dehydrogenase gene that may be optionally deleted are preferably deleted from all homologous genes present in the corresponding microorganism, but a recombinant microorganism from which some of these genes are deleted may also be applied to the present invention, when necessary.

According to an embodiment of the present invention, the fatty alcohol dehydrogenase gene may be selected from the group consisting of ADH1, ADH2, ADH3, ADH4, ADH5, ADH6, ADH7, ADH8, and FADH genes, but the present invention is not limited thereto. According to preferred embodiments of the present invention, the ADH1, ADH2, ADH3, ADH4, ADH5, ADH6, ADH7, ADH8, and FADH genes may comprise base sequences set forth in SEQ ID NOs: 1 to 9, respectively, but the present invention is not limited thereto.

According to another embodiment of the present invention, the fatty alcohol oxidase gene may be an FAO gene, but the present invention is not limited thereto. According to preferred embodiments of the present invention, the FAO gene may comprise a base sequence set forth in SEQ ID NO: 10, but the present invention is not limited thereto.

According to still another embodiment of the present invention, the fatty aldehyde dehydrogenase gene may be selected from the group consisting of FALDH1, FALDH2, FALDH3, and FALDH4 genes, but the present invention is not limited thereto. The FALDH1, FALDH2, FALDH3, and FALDH4 genes may comprise base sequences set forth in SEQ ID NOs: 11 to 14, respectively, but the present invention is not limited thereto.

According to an embodiment of the present invention, the β-oxidative metabolism pathway-related genes are preferably deleted from all homologous genes present in the corresponding microorganism, but a recombinant microorganism from which some of these genes are deleted may also be applied to the present invention, when necessary. The β-oxidative metabolism pathway-related genes preferably includes an acyl-CoA oxidase gene, and the acyl-CoA oxidase gene may be selected from the group consisting of ACO1, ACO2, ACO3, ACO4, ACO5, and ACO6 genes, but the present invention is not limited thereto (see FIG. 2 ). According to other preferred embodiments of the present invention, the ACO1, ACO2, ACO3, ACO4, ACO5, and ACO6 genes may comprise base sequences set forth in SEQ ID NOs: 15 to 20, respectively, but the present invention is not limited thereto.

In the present invention, the recombinant microorganism from which the genes selected from the fatty alcohol dehydrogenase gene, the fatty alcohol oxidase gene, the fatty aldehyde dehydrogenase gene, and the acyl-CoA oxidase gene are deleted may be prepared using conventional genetic recombinant technology known in the related art. In the present invention, the term “deletion” is used as a meaning generally encompassing a physical deletion of part or all of the corresponding gene, and also encompassing a situation in which a protein is not expressed from mRNA transcribed from the corresponding gene and a situation in which a protein expressed from the corresponding gene does not function. Examples of the genetic recombinant technology that may be used herein may include methods such as transformation, transduction, transfection, microinjection, electroporation, and the like, but the present invention is not limited thereto.

In the present invention, any microorganisms having both ω-oxidative and β-oxidative metabolism processes may be used without limitation. For example, eukaryotes including a yeast and prokaryotes including Escherichia coli may be used. According to an embodiment of the present invention, the yeast is preferably used as the microorganism. In this case, yeasts such as Yarrowia sp., Saccharomyces sp., Pichia sp., Candida sp., and the like may be used as the yeast without limitation. Among theses, Yarrowia hpolytica, Candida tropicalis, Candida infanticola, Saccharomyces cerevisiae, Pichia alcoholophia , or Candida mycoderma is preferably used. Yarrowia lipolytica is more preferably used.

As described above, in the case of the microorganism from which the fatty alcohol dehydrogenase and fatty alcohol oxidase genes and the β-oxidative metabolism pathway-related genes are deleted and the fatty aldehyde dehydrogenase gene is optionally deleted, when the alkane is supplied as the substrate, one of both terminals of the alkane is oxidized by an action of cytochrome P450 and an NADPH-cytochrome P450 reductase to form a primary alcohol. However, because the fatty alcohol dehydrogenase gene and the fatty alcohol oxidase gene are deleted, no further oxidation occurs anymore. Also, the primary alcohol thus formed is again used as a substrate so that the other terminal of the primary alcohol is oxidized by an action of the cytochrome P450 and the NADPH-cytochrome P450 reductase to form a diol as a secondary alcohol. When the alkane is used as the substrate as described above, the diol is formed through a two-step oxidation reaction, whereas the diol is formed through a one-step oxidation reaction when the alcohol other than the alkane is used as the substrate.

Also, the present invention provides a method for producing a medium chain diol, which comprises:

(1) preparing a recombinant microorganism from which one or more genes selected from the group consisting of fatty alcohol dehydrogenase and fatty alcohol oxidase genes in an ω-oxidative metabolism pathway are deleted, a fatty aldehyde dehydrogenase gene is optionally deleted, and β-oxidative metabolism pathway-related genes are also deleted; and

(2) treating the recombinant microorganism with a substrate to culture the recombinant microorganism.

In the present invention, the recombinant microorganism, from which the fatty alcohol dehydrogenase and/or fatty alcohol oxidase genes in the ω-oxidative metabolism pathway are deleted, the fatty aldehyde dehydrogenase gene is optionally deleted, and the β-oxidative metabolism pathway-related genes are also deleted, may be used to produce medium chain diols with high yield by preventing additional oxidation and β-oxidative metabolism of fatty alcohols. The fatty alcohol dehydrogenase gene, the fatty alcohol oxidase gene, the fatty aldehyde dehydrogenase gene, and the β-oxidative metabolism pathway-related genes are preferably deleted from all homologous genes present in the corresponding microorganism, but a recombinant microorganism from which some of these genes are deleted may also be applied to the present invention, when necessary.

In the present invention, any microorganisms having both ω-oxidative and β-oxidative metabolism processes may be used without limitation. For example, eukaryotes including a yeast and prokaryotes including Escherichia coli may be used. According to an embodiment of the present invention, the yeast is preferably used as the microorganism. In this case, yeasts such as Yarrowia sp., Saccharomyces sp., Pichia sp., Candida sp., and the like may be used as the yeast without limitation. Among theses, Yarrowia lipolytica, Saccharomyces cerevisiae, Candida tropicalis, Candida infanticola, Pichia alcoholophia , or Candida mycoderma is preferably used. Yarrowia lipolytica is more preferably used.

In the present invention, the recombinant microorganism from which the genes selected from the fatty alcohol dehydrogenase gene, the fatty alcohol oxidase gene, the fatty aldehyde dehydrogenase gene, and the acyl-CoA oxidase gene are deleted may be prepared using conventional genetic recombinant technology known in the related art. In the present invention, the term “deletion” is used as a meaning generally encompassing a physical deletion of part or all of the corresponding gene, and also encompassing a situation in which a protein is not expressed from mRNA transcribed from the corresponding gene and a situation in which a protein expressed from the corresponding gene does not function.

In the present invention, the term “diol” generally refers to a compound that contains two hydroxyl groups (—OH groups), and the term “medium chain diol” is used as a meaning encompassing all diol compounds having 5 to 30 carbon atoms, preferably 6 to 20 carbon atoms, and more preferably 8 to 16 carbon atoms.

In the present invention, the substrate of step (2) may be selected from the group consisting of a fatty acid-derived alcohol and alkane, but the present invention is not limited thereto. According to an embodiment of the present invention, alcohols having 5 to 30 carbon atoms, preferably 6 to 20 carbon atoms, and more preferably 8 to 16 carbon atoms may be used as the fatty acid-derived alcohol, but the present invention is not limited thereto. According to another embodiment of the present invention, alkanes having 5 to 30 carbon atoms, preferably 6 to 20 carbon atoms, and more preferably 8 to 16 carbon atoms may be used as the alkane, but the present invention is not limited thereto. According to preferred embodiments of the present invention, the alkane may be dodecane, but the present invention is not limited thereto. According to other preferred embodiments of the present invention, the medium chain diol may be 1,12-dodecanediol, but the present invention is not limited thereto.

Hereinafter, the present invention will be described in further detail with reference to examples thereof.

However, it should be understood that the following examples are just preferred examples for the purpose of illustration only and is not intended to limit or define the scope of the invention.