title: Capillary electrophoresis for the monitoring of carboxylic acid production by Gluconobacter oxydans.
abstract: Determination of carboxylic acids in Gluconobacter oxydans fermentations of wheat straw hydrolyzate was carried out. This matrix is of complex composition containing carbohydrates, organic compounds (e.g., amino acids, toxins), and inorganic salts making the analysis challenging even with separation techniques. A method based on capillary electrophoresis with indirect UV detection was developed for the simultaneous quantification of 18 carboxylic acids. The background electrolyte solution of ammonia, 2,3-pyridinedicarboxylic acid, and Ca2+ and Mg2+ salts, containing myristyltrimethylammonium hydroxide as a dynamic capillary coating reagent, was validated for the robust and repeatable separation of the carboxylic acids. Intraday relative standard deviations in the optimized method were less than 1.6% for migration times and between 1.0% and 5.9% for peak area. Interday relative standard deviations were less than 5.0% for migration times and between 5.7% and 9.3% for peak area. With 11 nl injected, detection limits for the analytes were between 10 and 43 micromol/l. Detection limits ranged from 0.1 to 0.5 pmol at signal-to-noise ratio of 3. The results demonstrated that wheat straw hydrolyzate was a suitable substrate for G. oxydans with a product yield of 45% for the formation of xylonic acid from xylose and 96% for the formation of gluconic acid from glucose.
authors.affiliation: VTT Biotechnology, P.O. Box 1000, Fin-02044 VTT, Espoo, Finland. heidi.turkia@vtt.fi
authors.forename: Heidi
authors.initials: H
authors.lastname: Turkia
authors.forename: Heli
authors.initials: H
authors.lastname: Sirén
authors.forename: Juha-Pekka
authors.initials: JP
authors.lastname: Pitkänen
authors.forename: Marilyn
authors.initials: M
authors.lastname: Wiebe
authors.forename: Merja
authors.initials: M
authors.lastname: Penttilä
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D003470:Culture Media / Q000494:pharmacology; D019075:Electrophoresis, Capillary / Q000379:methods*; D005285:Fermentation / Q000187:drug effects; D005942:Gluconates / Q000378:metabolism; D020600:Gluconobacter oxydans / Q000187:drug effects / Q000378:metabolism*; D006868:Hydrolysis; D015203:Reproducibility of Results; D014908:Triticum / Q000737:chemistry
chemical_list: D002264:Carboxylic Acids; D003470:Culture Media; D005942:Gluconates; C030691:gluconic acid