Patent ID: 8198053

Claim:
A fermentation broth or fermentation product containing a basic amino acid, which is obtainable by a method comprising culturing a bacterium having an ability to produce a basic amino acid in a liquid medium contained in a fermentation tank to produce and accumulate the basic amino acid in the medium, wherein amount of sulfate and/or chloride ions which function as counter ions of the basic amino acid is reduced by adjusting the total ammonia concentration in the medium during a period selected from the group consisting of: (A) when the pH of the medium increases due to a shortage of the counter ions caused by accumulation of the objective basic amino acid, and (B) when the pH increases due to the addition of cations to the medium: wherein the concentration of ammonium ions in the medium is at such a level that the sum of the ion equivalents of bicarbonate ions and/or carbonate ions and other anions dissolved in the medium is larger than the ion equivalent of the basic amino acid ionized from the basic amino acid accumulated in the medium, and wherein said total ammonia concentration in the medium is at a level not inhibiting the production of the basic amino acid by the bacterium, which is determined beforehand as follows: a) the bacterium is cultured in the medium having various pH values and various total ammonia concentrations within the range of 1 to 500 mM, b) productivity of the basic amino acid is measured at each pH value and each total ammonia concentration, and c) a total ammonia concentration providing 50% or more of productivity of the basic amino acid based on the productivity obtained under optimum conditions is determined for each pH value, wherein the medium or a processed product thereof is heated after the fermentation to eliminate bicarbonate ions and carbonate ions.