title: Kinetics and metabolism of Bifidobacterium adolescentis MB 239 growing on glucose, galactose, lactose, and galactooligosaccharides.
abstract: The kinetics and the metabolism of Bifidobacterium adolescentis MB 239 growing on galactooligosaccharides (GOS), lactose, galactose, and glucose were investigated. An unstructured unsegregated model for growth in batch cultures was developed, and kinetic parameters were calculated with a recursive algorithm. The growth rate and cellular yield were highest on galactose, followed by lactose and GOS, and were lowest on glucose. Lactate, acetate, and ethanol yields allowed the calculation of carbon fluxes toward fermentation products. Distributions between two- and three-carbon products were similar on all the carbohydrates (55 and 45%, respectively), but ethanol yields were different on glucose, GOS, lactose, and galactose, in decreasing order of production. Based on the stoichiometry of the fructose-6-phosphate shunt and on the carbon distribution among the products, the ATP yield was calculated. The highest yield was obtained on galactose, while the yields were 5, 8, and 25% lower on lactose, GOS, and glucose, respectively. Therefore, a correspondence among ethanol production, low ATP yields, and low biomass production was established, demonstrating that carbohydrate preferences may result from different distributions of carbon fluxes through the fermentative pathway. During the fermentation of a GOS mixture, substrate selectivity based on the degree of polymerization was exhibited, since lactose and the trisaccharide were the first to be consumed, while a delay was observed until longer oligosaccharides were utilized. Throughout the growth on both lactose and GOS, galactose accumulated in the cultural broth, suggesting that beta(1-4) galactosides can be hydrolyzed before they are taken up.
authors: Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183, 41100 Modena, Italy.
authors: Alberto
authors: A
authors: Amaretti
authors: Tatiana
authors: T
authors: Bernardi
authors: Elena
authors: E
authors: Tamburini
authors: Simona
authors: S
authors: Zanoni
authors: Mariella
authors: M
authors: Lomma
authors: Diego
authors: D
authors: Matteuzzi
authors: Maddalena
authors: M
authors: Rossi
mesh_terms: D019342:Acetic Acid / Q000032:analysis; D000255:Adenosine Triphosphate / Q000096:biosynthesis; D001644:Bifidobacterium / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism*; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D004734:Energy Metabolism; D000431:Ethanol / Q000032:analysis; D005285:Fermentation; D005690:Galactose / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007700:Kinetics; D019344:Lactic Acid / Q000032:analysis; D007785:Lactose / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D008962:Models, Theoretical; D009844:Oligosaccharides / Q000378:metabolism*
chemical_list: D009844:Oligosaccharides; D019344:Lactic Acid; D000431:Ethanol; D002244:Carbon; D000255:Adenosine Triphosphate; D005947:Glucose; D007785:Lactose; D019342:Acetic Acid; D005690:Galactose