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Appl. Environ. Microbiol., 08 1995, 3042-3050, Vol 61, No. 8
RB Hespell and MA Cotta
Hemicelluloses, mainly xylans, can be a major component of diets consumed
by ruminants and undergo various degrees of microbial digestion in the
rumen. The ability of Butyrivibrio fibrisolvens, a major xylanolytic
ruminal species, to degrade and utilize nine chemically and physically
different xylans for growth was examined. The arabinoxylans used included
two isolated from corncobs (CCX-A and CCX- B), a native xylan excreted by
corn cell tissue cultures (CX), an oxalic acid-treated, arabinose-depleted
CX, and oat spelt xylan. Except for CCX-A, these xylans were extensively
converted within 3 h of growth to acid-alcohol-soluble forms that remained
at high levels for the duration of culture growth. These xylans contain
mainly xylose and arabinose with small amounts of uronic acids. For a given
xylan, all three components were used at about the same rate and extent.
During the early stages of growth B. fibrisolvens also rapidly solubilized
glucuronoxylans from birchwood, larchwood, 4-O-methylglucuronoxylan, and
the xylose homopolymer xylan isolated from beechwood (BEWX). In contrast to
the findings for the arabinoxylans, little acid-alcohol- soluble
carbohydrate remained in these cultures after 9 h of growth, except for
BEWX. Initially, with birchwood, larchwood, and 4-O- methylglucuronoxylan
the uronic acid components were preferentially used over the xylose. Final
xylan utilization measured at 72 h for all xylans varied from 57% for CCX-A
to 92% for BEWX and was correlated with the initial 12-h utilization rate
for a given xylan. Since CCX-A and BEWX are both highly water insoluble,
this aspect did not appear to influence overall utilization.(ABSTRACT
TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Degradation and utilization by Butyrivibrio fibrisolvens H17c of xylans with different chemical and physical properties
Fermentation Biochemistry Research Unit, National Center for Agricultural Utilization Research, Peoria, IL 61604, USA.
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