The enrichment of a ruminal bacterium (Megasphaera elsdenii YJ-4) that produces the trans-10, cis-12 isomer of conjugated linoleic acid

J Appl Microbiol. 2002;92(5):976-82. doi: 10.1046/j.1365-2672.2002.01610.x.


Aims: To isolate predominant ruminal bacteria that produce trans-10, cis-12 conjugated linoleic acid (CLA) from linoleic acid (LA).

Methods and results: Mixed bacteria from ruminal contents of a cow fed grain were enriched with DL-lactate and trypticase. They produced more trans-10, cis-12 CLA than those that were not enriched (7 vs 2 microg mg protein(-1), P < 0.05). Enrichments had an abundance of large cocci that produced trans-10, cis-12 CLA from LA. Strain YJ-4 produced the most trans-10, cis-12 CLA (approx. 7 microg mg protein(-1)) and 16S rDNA sequencing indicated that YJ-4 was a strain of Megasphaera elsdenii. Megasphaera elsdenii T81 produced approx. 4 microg trans-10, cis-12 CLA mg protein(-1) while strains B159, AW106 and JL1 produced < 0.5 microg mg protein(-1). The trans-10, cis-12 CLA production of YJ-4 was first order with respect to cell concentration (0-800 microg protein ml(-1)), but kinetics were not first order with respect to substrate concentration.

Conclusions: Some M. elsdenii strains produce significant amounts of trans-10, cis-12 CLA.

Significance and impact of the study: Trans-10, cis-12 CLA appears to cause milk fat depression in cattle fed diets supplemented with grain and polyunsaturated fatty acids, but predominant ruminal bacteria that produced trans-10, cis-12 CLA from LA had not previously been isolated.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Bacteria / classification
  • Bacteria / genetics
  • Bacteria / growth & development*
  • Bacteria / isolation & purification
  • Caseins / metabolism
  • Cattle
  • Culture Media
  • DNA, Ribosomal / analysis
  • Lactic Acid / metabolism
  • Linoleic Acids / biosynthesis*
  • Linoleic Acids / metabolism*
  • Linoleic Acids, Conjugated
  • Molecular Sequence Data
  • Phylogeny
  • Protein Hydrolysates / metabolism
  • RNA, Ribosomal, 16S / genetics
  • Rumen / microbiology*
  • Sequence Analysis, DNA
  • Stereoisomerism


  • 10,12-octadecadienoic acid
  • Caseins
  • Culture Media
  • DNA, Ribosomal
  • Linoleic Acids
  • Linoleic Acids, Conjugated
  • Protein Hydrolysates
  • RNA, Ribosomal, 16S
  • trypticase-soy broth
  • Lactic Acid

Associated data

  • GENBANK/AY038993
  • GENBANK/AY038994
  • GENBANK/AY038995
  • GENBANK/AY038996