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Arabinogalactan Utilization in Continuous Cultures of Bifidobacterium longum: Effect of Co-culture with Bacteroides thetaiotaomicron

Authors :
Degnan, B. A.
Macfarlane, G. T.
Source :
Anaerobe; April 1995, Vol. 1 Issue: 2 p103-112, 10p
Publication Year :
1995

Abstract

Studies showed that the plant cell wall polysaccharide arabinogalactan supported growth of Bifidobacterium longum in batch culture. Galactose was also utilized, but not arabinose, the other major constituent sugar of the polymer. Enzymes required for hydrolysis of arabinogalactan ('arabinogalactanase', α-arabinopyranosidase, β-galactosidase) were inducible and cell-associated in B. longum, and their expression was repressed by glucose. Considerable amounts of α-arabinopyranosidase and β-galactosidase were synthesized during growth on arabinogalactan, but only low levels of arabinogalactanase were detected. B. longum only grew on arabinogalactan in continuous culture under putative carbon-excess conditions. In C-limited chemostats, the bifidobacterium could not establish unless Bacteroides thetaiotaomicron was present in co-culture. The relationship between the two organisms was not simply commensal; at low specific growth rates, bacteroides cell population densities were approximately 30% lower than those recorded in axenic culture, indicating the existence of competitive interactions with the bifidobacterium. In contrast, at high specific growth rates, a mutualistic association was observed, in that Bact. thetaiotaomicron was maintained in the chemostats at high dilution rates if bifidobacteria were also present. Measurements of residual carbohydrate in spent culture fluid from C-limited chemostats indicated that a large part of the arabinogalactan molecule could not be broken down by either B. longum or Bact. thetaiotaomicron alone, or in co-culture. Formate and acetate were the major fermentation products of B. longum cultured in the presence of high concentrations of arabinogalactan, confirming that these bacteria were growing under energy-limited conditions. Copyright 1995, 1999 Academic Press

Details

Language :
English
ISSN :
10759964 and 10958274
Volume :
1
Issue :
2
Database :
Supplemental Index
Journal :
Anaerobe
Publication Type :
Periodical
Accession number :
ejs823337
Full Text :
https://doi.org/10.1006/anae.1995.1005