Method for Producing Carboxylic Acid Using Methanol-Assimilating Bacterium

Abstract

A method for producing a carboxylic acid by a fermentation process which comprises culturing a methanol-assimilating bacterium capable of producing the carboxylic acid in a liquid medium containing methanol and a counter ion to produce and accumulate the carboxylic acid in the medium, further comprising the feeding of a substance comprising methanol and a counter ion to the medium by fed-batch culturing to maintain the total ionic strength within the fermentation medium at or below a certain level.

We claim: 
     
         1 . A method for producing carboxylic acid by fermentation comprising,
 A) culturing a methanol-assimilating bacterium that has an ability to produce the carboxylic acid in a liquid medium containing methanol and a counter ion,   B) collecting the carboxylic acid from the medium or the bacterium,   wherein a composition comprising methanol and a counter ion is fed to the medium by fed-batch culturing.   
     
     
         2 . The method of  claim 1 , wherein said counter ion is a monovalent ion. 
     
     
         3 . The method according to  claim 1 , wherein said counter ion is selected from the group consisting of ammonium chloride, ammonium glutamate, ammonium succinate, ammonium fumarate, ammonium aspartate, and combinations thereof. 
     
     
         4 . The method according to  claim 1 , wherein said carboxylic acid is an L-amino acid. 
     
     
         5 . The method according to  claim 1 , wherein said L-amino acid is L-lysine. 
     
     
         6 . The method according to  claim 1 , wherein said methanol-assimilating bacterium is of a genera selected from the group consisting  Acromobacter, Pseudomonas, Protaminobacter, Methanomonas, Microcyclus, Methylobacillus, Bacillus , and  Methylophilus.    
     
     
         7 . The method according to  claim 1 , wherein said methanol-assimilating bacterium has been modified to increase the activity of an enzyme selected from the group consisting of diaminopimelate dehydrogenase, diaminopimelate decarboxylase, aspartate semialdehyde dehydrogenase, and combinations thereof. 
     
     
         8 . The method according to  claim 6 , wherein DNA encoding dihydrodipicolinate synthase and/or aspartokinase that has been modified so it is not subject to feedback inhibition by L-lysine, is present in the bacterium. 
     
     
         9 . The method according to  claim 7 , wherein DNA encoding a variant lysE protein promoting the export of L-lysine to the outside of the cell when introduced into a methanol-assimilating bacterium, is present in the bacterium.