Presentation Title

Enriching branched-chain fatty acids in cellular lipids of rumen bacteria and protozoa

Project Collaborators

Jamie Burke, Dr. Sabrina Greenwood, Dr. Jana Kraft

Abstract

Branched-chain fatty acids (BCFA), such as 17:0 iso, are bioactive compounds that have been shown to have various positive human health effects. Milk is one of the main sources of BCFA (2% of total milk fat) due to the bacteria and protozoa that inhabit a cow’s rumen. Using exogenous (i.e., dietary) branched-chain amino acid (BCAA) precursors, microorganisms can synthesize BCFA and incorporate them into their cell membranes. This biosynthetic pathway of BCFA has been thoroughly studied in some bacterial species, including Bacillus subtilis, Escherichia coli, and Staphylococcus aureus, however, there is surprisingly little known on the synthesis pathway of BCFA in bacteria and protozoa in the context of the rumen ecosystem. We hypothesized that the supplementation of the BCAA precursor, leucine, would increase the content of BCFA in rumen bacterial and protozoal cell membranes in a rumen-simulating continuous culture fermenter. The objective of our study was to measure the composition and content of BCFA in bacterial and protozoal cell membranes following a dose response of leucine supplementation. In a 4x4 Latin square design, rumen contents were collected from four-ruminally fistulated dairy cows, transferred to four rumen-stimulating continuous culture fermenters, and randomly assigned to one of four leucine treatments: 1) control (CON) - a total mixed ration representative of a cow’s diet, 2) control supplemented with 150% leucine, 3) CON supplemented with 200% leucine, and 4) CON supplemented with 300% leucine. After a seven-day adaptation period, rumen fluid contents were collected daily for three consecutive days and fractionated to isolate bacteria and protozoa from the rumen fluid. Bacterial and protozoal fatty acids were analyzed using gas-liquid chromatography. Data on the fatty acid composition (g/100g FA) and content (mg fatty acid/g sample) of rumen bacterial and protozoal membranes in response to the dietary treatments of CON, 150%, 200%, and 300% leucine supplementation will be presented.

Primary Faculty Mentor Name

Jana Kraft

Secondary Mentor NetID

slgreenw

Secondary Mentor Name

Sabrina Greenwood

Status

Graduate

Student College

College of Agriculture and Life Sciences

Program/Major

Animal Science

Primary Research Category

Biological Sciences

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Enriching branched-chain fatty acids in cellular lipids of rumen bacteria and protozoa

Branched-chain fatty acids (BCFA), such as 17:0 iso, are bioactive compounds that have been shown to have various positive human health effects. Milk is one of the main sources of BCFA (2% of total milk fat) due to the bacteria and protozoa that inhabit a cow’s rumen. Using exogenous (i.e., dietary) branched-chain amino acid (BCAA) precursors, microorganisms can synthesize BCFA and incorporate them into their cell membranes. This biosynthetic pathway of BCFA has been thoroughly studied in some bacterial species, including Bacillus subtilis, Escherichia coli, and Staphylococcus aureus, however, there is surprisingly little known on the synthesis pathway of BCFA in bacteria and protozoa in the context of the rumen ecosystem. We hypothesized that the supplementation of the BCAA precursor, leucine, would increase the content of BCFA in rumen bacterial and protozoal cell membranes in a rumen-simulating continuous culture fermenter. The objective of our study was to measure the composition and content of BCFA in bacterial and protozoal cell membranes following a dose response of leucine supplementation. In a 4x4 Latin square design, rumen contents were collected from four-ruminally fistulated dairy cows, transferred to four rumen-stimulating continuous culture fermenters, and randomly assigned to one of four leucine treatments: 1) control (CON) - a total mixed ration representative of a cow’s diet, 2) control supplemented with 150% leucine, 3) CON supplemented with 200% leucine, and 4) CON supplemented with 300% leucine. After a seven-day adaptation period, rumen fluid contents were collected daily for three consecutive days and fractionated to isolate bacteria and protozoa from the rumen fluid. Bacterial and protozoal fatty acids were analyzed using gas-liquid chromatography. Data on the fatty acid composition (g/100g FA) and content (mg fatty acid/g sample) of rumen bacterial and protozoal membranes in response to the dietary treatments of CON, 150%, 200%, and 300% leucine supplementation will be presented.