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The role of microbes in rumen lipolysis and biohydrogenation and their manipulation

Marta Ribeiro Alves Lourenço UGent, E Ramos-Morales and RJ Wallace (2010) ANIMAL. 4(7). p.1008-1023
abstract
Despite the fact that the ruminant diet is rich in polyunsaturated fatty acids (PUFA), ruminant products - meat, milk and dairy - contain mainly saturated fatty acids (SFA) because of bacterial lipolysis and subsequent biohydrogenation of ingested PUFA in the rumen. The link between SFA consumption by man and coronary heart disease is well established. In contrast, ruminant products also contain fatty acids that are known to be beneficial to human health, namely conjugated linoleic acids (CLAs). The aims of research in this field have been to understand the microbial ecology of lipolysis and biohydrogenation and to find ways of manipulating ruminal microbes to increase the flow of PUFA and CLA from the rumen into meat and milk. This review describes our present understanding of the microbial ecology of ruminal lipid metabolism, including some apparently anomalous and paradoxical observations, and the status of how the metabolism may be manipulated and the possible consequential effects on other aspects of ruminal digestion. Intuitively, it may appear that inhibiting the ruminal lipase would cause more dietary PUFA to reach the mammary gland. However, lipolysis releases the non-esterified fatty acids that form the substrates for biohydrogenation, but which can, if they accumulate, inhibit the whole process. Thus, increasing lipase activity could be beneficial if the increased release of non-esterified PUFA inhibited the metabolism of CLA. Rumen ciliate protozoa do not carry out biohydrogenation, yet protozoal lipids are much more highly enriched in CLA than bacterial lipids. How could this happen if protozoa do not metabolise PUFA? The answer seems to lie in the ingestion of plant organelles, particularly chloroplasts, and the partial metabolism of the fatty acids by contaminating bacteria. Bacteria related to Butyrivibrio fibrisolvens are by far the most active and numerous biohydrogenating bacteria isolated from the rumen. But do we misunderstand the role of different bacterial species in biohydrogenation because there are uncultivated species that we need to understand and include in the analysis? Manipulation methods include dietary vegetable and fish oils and plant-derived chemicals. Their usefulness, efficacy and possible effects on fatty acid metabolism and on ruminal microorganisms and other areas of their metabolism are described, and areas of opportunity identified.
Please use this url to cite or link to this publication:
author
organization
year
type
journalArticle (proceedingsPaper)
publication status
published
subject
keyword
lipase, biohydrogenation, rumen, microbial protein synthesis, cellulose digestion, CONJUGATED LINOLEIC-ACID, UNSATURATED FATTY-ACIDS, ESSENTIAL OIL COMPOUNDS, IN-VITRO DEGRADATION, LACTATING DAIRY-COWS, MILK-FAT, RUMINAL FERMENTATION, FISH-OIL, ANAEROVIBRIO-LIPOLYTICA, METHANE PRODUCTION
journal title
ANIMAL
Animal
volume
4
issue
7
pages
1008 - 1023
conference name
11th International symposium on Ruminant Physiology
conference location
Clermont Ferrand, France
conference start
2009-09-06
conference end
2009-09-09
Web of Science type
Proceedings Paper
Web of Science id
000279124100004
JCR category
VETERINARY SCIENCES
JCR impact factor
1.458 (2010)
JCR rank
32/145 (2010)
JCR quartile
1 (2010)
ISSN
1751-7311
DOI
10.1017/S175173111000042X
language
English
UGent publication?
yes
classification
A1
copyright statement
I have transferred the copyright for this publication to the publisher
id
1083480
handle
http://hdl.handle.net/1854/LU-1083480
date created
2010-12-06 13:01:23
date last changed
2011-08-01 00:30:29
@article{1083480,
  abstract     = {Despite the fact that the ruminant diet is rich in polyunsaturated fatty acids (PUFA), ruminant products - meat, milk and dairy - contain mainly saturated fatty acids (SFA) because of bacterial lipolysis and subsequent biohydrogenation of ingested PUFA in the rumen. The link between SFA consumption by man and coronary heart disease is well established. In contrast, ruminant products also contain fatty acids that are known to be beneficial to human health, namely conjugated linoleic acids (CLAs). The aims of research in this field have been to understand the microbial ecology of lipolysis and biohydrogenation and to find ways of manipulating ruminal microbes to increase the flow of PUFA and CLA from the rumen into meat and milk. This review describes our present understanding of the microbial ecology of ruminal lipid metabolism, including some apparently anomalous and paradoxical observations, and the status of how the metabolism may be manipulated and the possible consequential effects on other aspects of ruminal digestion. Intuitively, it may appear that inhibiting the ruminal lipase would cause more dietary PUFA to reach the mammary gland. However, lipolysis releases the non-esterified fatty acids that form the substrates for biohydrogenation, but which can, if they accumulate, inhibit the whole process. Thus, increasing lipase activity could be beneficial if the increased release of non-esterified PUFA inhibited the metabolism of CLA. Rumen ciliate protozoa do not carry out biohydrogenation, yet protozoal lipids are much more highly enriched in CLA than bacterial lipids. How could this happen if protozoa do not metabolise PUFA? The answer seems to lie in the ingestion of plant organelles, particularly chloroplasts, and the partial metabolism of the fatty acids by contaminating bacteria. Bacteria related to Butyrivibrio fibrisolvens are by far the most active and numerous biohydrogenating bacteria isolated from the rumen. But do we misunderstand the role of different bacterial species in biohydrogenation because there are uncultivated species that we need to understand and include in the analysis? Manipulation methods include dietary vegetable and fish oils and plant-derived chemicals. Their usefulness, efficacy and possible effects on fatty acid metabolism and on ruminal microorganisms and other areas of their metabolism are described, and areas of opportunity identified.},
  author       = {Ribeiro Alves Louren\c{c}o, Marta and Ramos-Morales, E and Wallace, RJ},
  issn         = {1751-7311},
  journal      = {ANIMAL},
  keyword      = {lipase,biohydrogenation,rumen,microbial protein synthesis,cellulose digestion,CONJUGATED LINOLEIC-ACID,UNSATURATED FATTY-ACIDS,ESSENTIAL OIL COMPOUNDS,IN-VITRO DEGRADATION,LACTATING DAIRY-COWS,MILK-FAT,RUMINAL FERMENTATION,FISH-OIL,ANAEROVIBRIO-LIPOLYTICA,METHANE PRODUCTION},
  language     = {eng},
  location     = {Clermont Ferrand, France},
  number       = {7},
  pages        = {1008--1023},
  title        = {The role of microbes in rumen lipolysis and biohydrogenation and their manipulation},
  url          = {http://dx.doi.org/10.1017/S175173111000042X},
  volume       = {4},
  year         = {2010},
}

Chicago
Ribeiro Alves Lourenço, Marta, E Ramos-Morales, and RJ Wallace. 2010. “The Role of Microbes in Rumen Lipolysis and Biohydrogenation and Their Manipulation.” Animal 4 (7): 1008–1023.
APA
Ribeiro Alves Lourenço, M., Ramos-Morales, E., & Wallace, R. (2010). The role of microbes in rumen lipolysis and biohydrogenation and their manipulation. ANIMAL, 4(7), 1008–1023. Presented at the 11th International symposium on Ruminant Physiology.
Vancouver
1.
Ribeiro Alves Lourenço M, Ramos-Morales E, Wallace R. The role of microbes in rumen lipolysis and biohydrogenation and their manipulation. ANIMAL. 2010;4(7):1008–23.
MLA
Ribeiro Alves Lourenço, Marta, E Ramos-Morales, and RJ Wallace. “The Role of Microbes in Rumen Lipolysis and Biohydrogenation and Their Manipulation.” ANIMAL 4.7 (2010): 1008–1023. Print.