Aims: To determine if Butyrivibrio fibrisolvens strain 3071 is able to use fructose polymers for growth and to identify the enzymes involved in their digestion. Methods and Results: Strain 3071 utilized 97, 89, 85 and 60% of sucrose, timothy grass fructan, inulin oligosaccharides and inulin, respectively, in the growth medium. A cell extract from timothy grass fructan-grown bacteria was used for identification of fructanolytic enzymes by anion exchange chromatography, gel filtration, zymography and thin-layer chromatography. The bacterium synthesizes a specific endolevanase and a nonspecific beta-fructofuranosidase. Both enzymes occurred in two forms differing in molecular weight. The beta-fructofuranosidase was not able to digest long-chain inulin or timothy grass fructan, but degraded inulin oligosaccharides and sucrose. Addition of 1,4-dithioerythritol to an enzyme solution did not affect the activity of endolevanase(s), but increased the ability of beta-fructofuranosidase to digest sucrose. The digestion of timothy grass fructan by endolevanase(s) was described by Michaelis-Menten kinetics in which K-m = 2.82 g l(-1) and V-max = 4.01 mu moles reducing sugar equivalents x mg(-1) x min(-1). Conclusion: Strain 3071 synthesizes enzymes enabling it to use grass fructans for growth. Significance and Impact of the Study: Butyrivibrio fibrisolvens strain 3071 can be considered a member of the rumen fructanolytic guild.