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Appl Environ Microbiol, March 1998, p. 907-913, Vol. 64, No. 3
AgResearch Grasslands, Palmerston North, New
Zealand
Received 7 August 1997/Accepted 4 December 1997
A competitive PCR technique was used to enumerate the proteolytic
bacterium Clostridium proteoclasticum from the rumen. A PCR
primer, which circumscribes this organism and several closely related
strains, was designed for a variable region within their 16S rRNA genes
and was used in conjunction with a universal forward primer. This
primer pair was tested for specificity against 85 ruminal bacterial
strains. An internal control DNA was constructed for use in competitive
PCRs and was shown to amplify under the same reaction conditions and
with the same amplification efficiency as the target DNA. DNA from a
known number of C. proteoclasticum cells was
coamplified with the internal control to construct a standard curve.
Rumen samples were collected from eight dairy cows fed four diets in
rotation: high nitrogen, high nitrogen supplemented with carbohydrate,
low nitrogen, and low nitrogen supplemented with carbohydrate. DNA
extracted from these and spiked with internal control DNA was amplified
with the C. proteoclasticum primer pair. The relative
intensities of the PCR products were used to quantitate the numbers of
C. proteoclasticum cell equivalents from the rumen
samples. The numbers ranged from 2.01 × 106
ml
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Detection of Clostridium proteoclasticum
and Closely Related Strains in the Rumen by Competitive PCR
1 to 3.12 × 107 ml
1.
There was no significant effect on the numbers of C. proteoclasticum detected in rumen samples among cows fed the four
diets. The utility of the competitive PCR approach for quantifying
ruminal bacterial populations in vivo and the occurrence of
C. proteoclasticum in forage-fed dairy cows are
discussed.
*
Corresponding author. Mailing address: AgResearch,
Ruminant Digestion and Metabolism, Grasslands Research Centre, Tennent Drive, Private Bag 11008, Palmerston North, New Zealand. Phone: 64 6 356 8019. Fax: 64 6 351 8003. E-mail:
attwoodg{at}agresearch.cri.nz.
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