Enumeration of Megasphaera elsdenii in rumen contents by real-time Taq nuclease assay

J Appl Microbiol. 2002;92(4):753-8. doi: 10.1046/j.1365-2672.2002.01580.x.


Aims: To develop a real-time Taq nuclease assay (TNA) to enable the in vivo enumeration of Megasphaera elsdenii.

Methods and results: Megasphaera elsdenii YE34 was phenotypically characteristic of the species and had 16S rDNA sequence similarity of 98% to previously described isolates. Calibration of the number of cells of M. elsdenii against the cycle threshold of fluorescent dye release gave a straight-line relationship with a correlation coefficient approximating unity. The specificity of the assay for M. elsdenii was confirmed by performing it against a panel of 24 heterogeneous, mainly ruminal bacteria. Megasphaera elsdenii was not detected in ruminal contents from a pasture-fed steer but was readily detected 2 and 50 h after the probiotic introduction of the bacterium into the rumen.

Conclusions: Real-time TNA has provided a sensitive and specific means of enumerating the M. elsdenii population in rumen contents.

Significance and impact of the study: Megasphaera elsdenii is an important lactate-degrading ruminal bacterium that has been selected for probiotic use to prevent acidosis and enhance starch utilization in grain-fed cattle. The assay developed in this study provides a tool for determining the ability of probiotically-introduced M. elsdenii to establish useful populations in the rumen.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • DNA, Bacterial / analysis
  • DNA, Bacterial / genetics
  • Molecular Sequence Data
  • Polymerase Chain Reaction / methods*
  • RNA, Ribosomal, 16S / genetics
  • Rumen / microbiology*
  • Sensitivity and Specificity
  • Sequence Analysis, DNA
  • Species Specificity
  • Taq Polymerase / metabolism*
  • Veillonellaceae / genetics
  • Veillonellaceae / isolation & purification*


  • DNA, Bacterial
  • RNA, Ribosomal, 16S
  • Taq Polymerase

Associated data

  • GENBANK/AF283705