Fermentation of xylans by Butyrivibrio fibrisolvens and other ruminal bacteria

Abstract

The ability of Butyrivibriofibrisolvens and other ruminal bacteria (6 species, 18 strains) to ferment a crude xylan from wheat straw or to ferment xylans from larchwood or oat spelts was studied. Liquid cultures were monitored for carbohydrate utilization, cell growth (protein), and fermentation acid production. B.fibrisolvens 49, H17c, AcTF2, and Dl grew almost as well on one or more of the xylans as they did on cellobiose-maltose. B. fibrisolvens 12, R28, A38, X1OC34, ARD22a, and X6C61 exhibited moderate growth on xylans. Partial fermentation of xylans was observed with Bacteroides ruminicola B14, Bacteroides succinogenes S85, Ruminococcus albus 7, Ruminococcus flavefaciens C94 and FD1, and Succinivibrio dextrinosolvens 22B. All xylans tested appeared to have a small fraction of carbohydrate that supported low levels of growth of nonxylanolytic strains such as Selenomonas ruminantium HD4. Compared to growth on hexoses, the same array of fermentation acids was produced upon growth on xylans for most strains; however, reduced lactate levels were observed for B. fibrisolvens 49 and Selenomonas ruminantium HD4. Measurements of enzyme activities of B. fibrisolvens AcTF2, 49, H17c, and D1 indicated that the xylobiase activities were cell associated and that the xylanase activities were predominantly associated with the culture fluid. The pattern of expression of these enzymes varied both between strains and between the carbon sources on which the strains were grown.

Development of molecular methods for identification of Streptococcus bovis from human and ruminal origins

“…The sources of the strains have been previously identi¢ed [18], except strains RG [3] and FM [4]. All strains were grown anaerobically in routine growth medium (RGM, [19]), a complex Trypticase-yeast extract medium, containing 0.2% glucose. Puri¢ed DNA used for hybridizations and PCR analyses was isolated as described previously [11,20].…”

Heterologous expression of the Bacteroides ruminicola xylanase gene in Bacteroides fragilis and Bacteroides uniformis

“…E. coh strains were grown on LB medium (10 g of tryptone, 5 g of yeast extract, 5 g NaC1 per liter) or LB supplemented with ampicillin (50 ttg/mi), tetracycline (10 /~g/ml), or trimethoprim (200 pg/ml) for maintenance of plasmlds. B. rwmmcola were grown anaerobically on RGM medium, a complex yeast extract-trypticase-saits medium [8] containing 0.270 carbon source.…”

Evidence for the possible involvement of Selenomonas ruminantium in rumen fiber digestion

“…Selenomonas ruminantium also appears to be functionally diverse, because S. ruminantium HD4 possesses CMCase, whereas other S. ruminantium strains do not. The strain HD4 also possesses xylanolytic activity, even though it is weak (Hespell et al, 1987). Pristas et al (2008) have stated the necessity for further study of rumen selenomonas, pointing out the complex genetic structure within the S. ruminantium population.…”