|Kim, Y - CORNELL UNIVERSITY|
|Rychlik, J - CORNELL UNIVERSITY|
|Liu, R - CORNELL UNIVERSITY|
Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: June 15, 2001
Publication Date: August 15, 2001
Citation: Kim, Y.J., Rychlik, J.L., Russell, J.B., Liu, R.H. 2001. In vitro production of conjugated linoleic acid (cla) by ruminal bacteria and identification of megasphaera elsdenii as a trans-10, cis-12 cla isomerproducing bacterium. Annual Meeting of the Institute of Food Technologists. p. 51. Technical Abstract: Trans-10, cis-12 conjugated linoleic acid (CLA) causes milk fat depression in cattle fed grain-based diets, but the predominant ruminal bacteria that produced trans-10, cis-12 CLA had not previously been isolated. When cattle were fed 100% hay or 90% grain, the ruminal pH values were 6.8 and 6.0, respectively. Mixed ruminal bacteria from cattle fed grain produced more trans-10, cis-12 CLA than bacteria from cattle fed hay, even if both bacterial preparations were resuspended in a basal medium that had been adjusted to 6.8. When bacteria from a cow fed grain were provided with DL-lactate and Trypticase, trans-10, cis-12 CLA increased (7 versus 2 ug/mg protein). Bacteria that were repeatedly transferred with lactate and Trypticase produced >6 ug trans-10, cis-12 CLA per mg protein, and large cocci predominated. Several strains were isolated, and strain YJ-4 produced the most trans-10, cis-12 CLA. 16S rDNA sequencing indicated that tYJ-4 was a strain of Megasphaera elsdenii. The involvement of M. elsdenii in trans-10, cis-12 CLA production and milk fat depression is consistent with the observation that M. elsdenii is a lactate-utilizing bacterium and is found at high numbers in cattle fed grain. However, it has long been noted that some grain-fed cattle do not produce low milk fat, and some M. elsdenii strains did not produce nearly as much trans-10, cis-12 CLA as YJ-4.