Microorganism producing eicosapentaenoic acid and method for producing eicosapentaenoic acid

Abstract

An object of the present invention is to provide a microorganism that efficiently produces EPA and a method for producing EPA using the microorganism. The present invention relates to a microorganism having an ability to produce docosahexaenoic acid (DHA), wherein the microorganism contains a protein composed of an amino acid sequence in which at least one of the amino acid residues at positions 6, 65, 230, 231, and 275 in the amino acid sequence represented by SEQ ID NO: 2 has been substituted with another amino acid residue (mutated OrfB), and is capable of producing eicosapentaenoic acid (EPA), and the like.

1 . A microorganism having an ability to produce docosahexaenoic acid (DHA), wherein the microorganism contains a mutated OrfB homolog protein that is a homolog of a protein composed of an amino acid represented by SEQ ID NO: 2, except that at least one of the amino acid residues corresponding to amino acids at positions 6, 65, 230, 231, and 275 in SEQ ID NO: 2 has been substituted with another amino acid residue, and wherein the mutated OrfB homolog protein gives the microorganism an ability to produce eicosapentaenoic acid (EPA). 
     
     
         2 . The microorganism according to  claim 1 , wherein the microorganism having an ability to produce DHA is a Labyrinthulomycetes microorganism. 
     
     
         3 . The microorganism according to  claim 2 , wherein the Labyrinthulomycetes microorganism is a Labyrinthulomycetes microorganism belonging to the genus  Aurantiochytrium , the genus  Thraustochytrium , the genus  Ulkenia , the genus  Parietichytrium , the genus  Labyrinthula , the genus  Aplanochytrium , the genus  Oblongichytrium , or the genus  Schizochytrium.    
     
     
         4 . The microorganism according to  claim 1 , wherein the microorganism having an ability to produce DHA is a microorganism in which genes encoding respective domains described in the following (a) to (j) having an activity of synthesizing DHA have been introduced into a microorganism that does not have a DHA metabolic pathway:
 (a) a β-ketoacyl-ACP synthase (hereinafter referred to as KS) domain;   (b) a malonyl-CoA:ACP acyltransferase (hereinafter referred to as MAT) domain;   (c) an acyl carrier protein (ACP) domain;   (d) a ketoreductase (hereinafter referred to as KR) domain;   (e) a polyketide synthase dehydratase (hereinafter referred to as PS-DH) domain;   (f) a chain elongation factor (hereinafter, referred to as CLF) domain;   (g) an acyltransferase (hereinafter referred to as AT) domain;   (h) a FabA-like β-hydroxyacyl-ACP dehydratase (hereinafter referred to as FabA-DH) domain;   (i) an enoyl-ACP reductase (hereinafter referred to as ER) domain; and   (j) a phosphopantetheine transferase (hereinafter referred to as PPT) domain.   
     
     
         5 . The microorganism according to  claim 4 , wherein the microorganism that does not have a DHA metabolic pathway is a microorganism belonging to the genus  Escherichia , the genus  Bacillus , the genus  Corynebacterium , the genus  Yarrowia , the genus  Saccharomyces , the genus  Candida , or the genus  Pichia.    
     
     
         6 . A method for producing EPA or an EPA-containing composition, comprising:
 culturing the microorganism according to  claim 1  in a culture medium so as to produce and accumulate EPA or an EPA-containing composition in a culture, and   collecting EPA or the EPA-containing composition from the culture.   
     
     
         7 . The microorganism according to  claim 1 , wherein the mutated OrfB homolog protein, in the absence of the mutation wherein at least one of the amino acid residues corresponding to amino acids at positions 6, 65, 230, 231, and 275 in SEQ ID NO: 2 has been substituted with another amino acid residue, does not give the microorganism an ability to produce EPA.