Patent ID: 7217837

Claim:
A method for producing an organic acid A, which method comprises subjecting an ammonium salt of said organic acid A to reactive crystallization with an acid B, wherein said organic acid A has a pKa(A) and said acid B has a pKa(B) which satisfy the following formula (1): pKa(A)≦pKa(B) (1) where pKa(A) and pKa(B) represent ionization indices of said organic acid A and said acid B, respectively, provided that when either of said organic acid A or said acid B have plural ionization index values, pKa(A) and pKa(B) represent the minimum pKa among them, to precipitate said organic acid A in solid form, wherein said ammonium salt of said organic acid A is obtained by a process comprising bioconversion of a carbon source by a microorganism in the presence of at least one neutralizing agent selected from the group consisting of ammonia, ammonium carbonate, and urea, to obtain said ammonium salt of said organic acid.