Patent GB-1398337-A (GB)
Title: Method of controlling ferntation process
IPC: C12N1/20
Filed: 1972-08-23
Abstract: 1398337 Fermentation processes, e.g. for making glutamic acid or lysine AJINOMOTO CO Inc 23 Aug 1972 [26 Aug 1971 14 Sept 1971] 39337/72 Heading C2C [Also in Divisions C3 and C6] Fermentation processes in which an assimilable, water-soluble organic acid is fed as a carbon source to a culture medium containing bicarbonate ions when the pH of the culture medium attains or exceeds a particular value and in which the pH of the culture medium is to be maintained within a predetermined range and the concentration of the organic acid anions is to be maintained within a predetermined range suitable for microorganic growth and fermentative production, are controlled as follows: (a) when the concentration of the organic acid anions reaches the upper limit of its predetermined range, the concentration of bicarbonate ions present in the culture medium is increased by increasing the partial pressure of carbon dioxide in the fermentation vessel and/or by raising said particular value of pH to a higher level; and (b) when the concentration of the organic acid anions reaches the lower limit of the predetermined range, the concentration of bicarbonate ions present in the culture medium is decreased by decreasing the partial pressure of carbon dioxide and/or by reducing said particular value of pH to a lower level, said particular value of pH remaining within the predetermined range of pH. The partial pressure of carbon dioxide can be adjusted by changing the flow rate of air (required in an aerobic fermentation) or the pressure of gaseous phase in the fermentation vessel or by introducing carbon dioxide into the fermentation vessel. Examples and comparative experiments disclose that the above defined procedure yields higher conversion ratios than when the concentration of organic acid is used directly to control the pH, or the concentration of organic acid is kept constant at the expense of the pH. The examples are directed to: (1) the fermentation of acetic acid by Bacillus sp. (FERM-P 304) to produce alkaline protease, in which the concentration of acetic acid and the pH of the culture medium were kept at between 0À2 and 0À5 g/dl. and between 7À8 and 8À0 respectively through adjusting the rate of CO 2  supply from a reservoir to the fermenter whereby the concentration of bicarbonate ions in the culture medium was regulated; (2) as (1) except that when the concentration of acetic acid was below 0À20 g./dl., the set point of pH for feeding 70% acetic acid solution, which had originally been at 7À8, was changed to a lower point (by which the concentration of bicarbonate ions was decreased), and when the concentration was above 0À5 g./dl. the set point of pH was changed to a higher point (by which the concentration of bicarbonate ions was increased). Examples 3 to 5 describe the production of glutamic acid employing Brevibaeterium flavum ATCC 14067 on acetic acid/ammonium acetate and Brevibacterium lactsfermentum ATCC 13869 on benzoic acid/ammonium benzoate. Example 6 describes the production of lysine by fermentation of acetic acid/ammonium acetate with Brevibacterium flavum ATCC 21129. Other organic acid substrates and fermentation products are particularly mentioned.