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Applied and Environmental Microbiology, July 1999, p. 3075-3083, Vol. 65, No. 7
CSIRO Tropical Agriculture,
Received 8 December 1998/Accepted 29 March 1999
Tannins in forages complex with protein and reduce the availability
of nitrogen to ruminants. Ruminal bacteria that ferment protein or
peptides in the presence of tannins may benefit digestion of these
diets. Bacteria from the rumina of sheep and goats fed Calliandra
calothyrsus (3.6% N and 6% condensed tannin) were isolated on
proteinaceous agar medium overlaid with either condensed (calliandra tannin) or hydrolyzable (tannic acid) tannin. Fifteen genotypes were
identified, based on 16S ribosomal DNA-restriction fragment length
polymorphism analysis, and all were proteolytic and fermented peptides
to ammonia. Ten of the isolates grew to high optical density (OD) on
carbohydrates (glucose, cellobiose, xylose, xylan, starch, and
maltose), while the other isolates did not utilize or had low growth on
these substrates. In pure culture, representative isolates were unable
to ferment protein that was present in calliandra or had been complexed
with tannin. One isolate, Lp1284, had high protease activity (80 U), a
high specific growth rate (0.28), and a high rate of ammonia production
(734 nmol/min/ml/OD unit) on Casamino Acids and Trypticase Peptone.
Phylogenetic analysis of the 16S ribosomal DNA sequence showed that
Lp1284 was related (97.6%) to Clostridium botulinum NCTC
7273. Purified plant protein and casein also supported growth of Lp1284
and were fermented to ammonia. This is the first report of a
proteolytic, ammonia-hyperproducing bacterium from the rumen. In
conclusion, a diverse group of proteolytic and peptidolytic bacteria
were present in the rumen, but the isolates could not digest protein
that was complexed with condensed tannin.
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Isolation and Characterization of Proteolytic
Ruminal Bacteria from Sheep and Goats Fed the Tannin-Containing Shrub
Legume Calliandra calothyrsus
*
Corresponding author. Mailing address: CSIRO Tropical
Agriculture, Private Bag No. 3, P.O., Indooroopilly, 4068 QLD,
Australia. Phone: 61 7 3214 2820. Fax: 61 7 3214 2880. E-mail:
Chris.McSweeney{at}tag.csiro.au.
Applied and Environmental Microbiology, July 1999, p. 3075-3083, Vol. 65, No. 7
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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