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Control of acetic acid concentration by pH‐stat continuous substrate feeding in heterotrophic culture phase of two‐stage cultivation of Alcaligenes eutrophus for production of P(3HB) from CO 2 , H 2 , and O 2 under non‐explosive conditions
Author(s) -
Sugimoto Toshikazu,
Tsuge Takeharu,
Tanaka Kenji,
Ishizaki Ayaaki
Publication year - 1999
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19990320)62:6<625::aid-bit1>3.0.co;2-d
Subject(s) - acetic acid , heterotroph , fed batch culture , chemistry , autotroph , substrate (aquarium) , biochemistry , industrial fermentation , oxidizing agent , fructose , bioreactor , chromatography , food science , biology , bacteria , fermentation , organic chemistry , ecology , genetics
A‐two stage culture method of hydrogen‐oxidizing bacterium, Alcaligenes eutrophus, is used to produce poly‐ d ‐3‐hydroxybutyrate, P(3HB) from CO 2 , O 2 , and H 2 without using a very high oxygen transfer rate while maintaining the O 2 concentration in gas phase below 6.9 (v/v)% to prevent detonation of the gas mixture. The two‐stage method consists of a heterotrophic culture using fructose as carbon source for exponential cell growth and an autotrophic culture for P(3HB) accumulation. We investigated the use of acetic acid as a cheaper carbon source than fructose for the heterotrophic culture in the two‐stage method. However, the acetate concentration in the culture system must be maintained at 1.0 g · dm −3 since its inhibitory effect on the cell growth is very strong. Then, high cell density cultivation of A. eutrophus was investigated by pH‐stat continuous feeding of acetic acid to control acetate concentration. As a result, acetate concentration was automatically maintained around 1.0 g · dm −3 by using a feed with a composition in CH 3 COOH/CH 3 COONH 4 /KH 2 PO 4 molar ratio of 5:1:0.084. Cell concentration increased to 48.6 g · dm −3 after 21 h of cultivation. The cell mass grown in the fed‐batch culture on acetic acid was useful for P(3HB) production from CO 2 in the subsequent autotrophic culture stage. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 62: 625–631, 1999.