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Process optimization of continuous gluconic acid fermentation by isolated yeast‐like strains of Aureobasidium pullulans
Author(s) -
Anastassiadis Savas,
Aivasidis Alexander,
Wandrey Christian,
Rehm HansJürgen
Publication year - 2005
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/bit.20533
Subject(s) - gluconic acid , aureobasidium pullulans , fermentation , food science , chemostat , biochemistry , extracellular , yeast , pullulan , chemistry , chromatography , biology , bacteria , polysaccharide , genetics
This study was focused on the optimization of a new fermentation process for continuous gluconic acid production by the isolated yeast‐like strain Aureobasidium pullulans DSM 7085 (isolate 70). Operational fermentation parameters were optimized in chemostat cultures, using a defined glucose medium. Different optima were found for growth and gluconic acid production for each set of operation parameters. Highest productivity was recorded at pH values between 6.5 and 7.0 and temperatures between 29 and 31°C. A gluconic acid concentration higher than 230 g/L was continuously produced at residence times of 12 h. A steady state extracellular gluconic acid concentration of 234 g/L was measured at pH 6.5. 122% air saturation yielded the highest volumetric productivity and product concentration. The biomass‐specific productivity increased steadily upon raising air saturation. An intracellular gluconic acid concentration of about 159 g/L (0.83 mol) was determined at 31°C. This is to be compared with an extracellular concentration of 223 g/L (1.16 mol), which indicates the possible existence of an active transport system for gluconic acid secretion, or the presence of extracellular glucose oxidizing enzymes. The new process provides significant advantages over the traditional discontinuous fungi operations. The process control becomes easier, thus offering stable product quality and quantity. © 2005 Wiley Periodicals, Inc.