The enrichment of a ruminal bacterium (Megasphaera elsdenii YJ-4) that produces the trans-10, cis-12 isomer of conjugated linoleic acid.
OBJECTIVE
To isolate predominant ruminal bacteria that produce trans-10, cis-12 conjugated linoleic acid (CLA) from linoleic acid (LA).


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.


CONCLUSIONS
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.
Kim
Y J
YJ
Department of Food Science, Cornell University, Ithaca, NY 14853, USA.
Liu
R H
RH
Rychlik
J L
JL
Russell
J B
JB
D000818:Animals; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D002364:Caseins / Q000378:metabolism; D002417:Cattle; D003470:Culture Media; D004275:DNA, Ribosomal / Q000032:analysis; D019344:Lactic Acid / Q000378:metabolism; D008041:Linoleic Acids / Q000096:biosynthesis* / Q000378:metabolism*; D044243:Linoleic Acids, Conjugated; D008969:Molecular Sequence Data; D010802:Phylogeny; D011492:Protein Hydrolysates / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012417:Rumen / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013237:Stereoisomerism
C094849:10,12-octadecadienoic acid; D002364:Caseins; D003470:Culture Media; D004275:DNA, Ribosomal; D008041:Linoleic Acids; D044243:Linoleic Acids, Conjugated; D011492:Protein Hydrolysates; D012336:RNA, Ribosomal, 16S; C026375:trypticase-soy broth; D019344:Lactic Acid