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Applied and Environmental Microbiology, September 2004, p. 5659-5666, Vol. 70, No. 9
0099-2240/04/$08.00+0     DOI: 10.1128/AEM.70.9.5659-5666.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Microbial Species Involved in Production of 1,2-sn-Diacylglycerol and Effects of Phosphatidylcholine on Human Fecal Microbiota

Jelena Vulevic,1* Anne L. McCartney,1 Jennifer M. Gee,2 Ian T. Johnson,2 and Glenn R. Gibson1

Food Microbial Sciences Unit, School of Food Biosciences, The University of Reading, Reading,1 Institute of Food Research, Colney, Norwich, United Kingdom2

Received 26 January 2004/ Accepted 12 May 2004

1,2-sn-Diacylglycerols (DAGs) are activators of protein kinase C (PKC), which is involved in the regulation of colonic mucosal proliferation. Extracellular DAG has been shown to stimulate the growth of cancer cell lines in vitro and may therefore play an important role in tumor promotion. DAG has been detected in human fecal extracts and is thought to be of microbial origin. Hitherto, no attempts have been made to identify the predominant fecal bacterial species involved in its production. We therefore used anaerobic batch culture systems to determine whether fecal bacteria could utilize phosphatidylcholine (0.5% [wt/vol]) to produce DAG. Production was found to be dependent upon the presence of the substrate and was enhanced in the presence of high concentrations of deoxycholate (5 and 10 mM) in the growth medium. Moreover, its production increased with the pH, and large inter- and intraindividual variations were observed between cultures seeded with inocula from different individuals. Clostridia and Escherichia coli multiplied in the fermentation systems, indicating their involvement in phosphatidylcholine metabolism. On the other hand, there was a significant decrease in the number of Bifidobacterium spp. in the presence of phosphatidylcholine. Pure-culture experiments showed that 10 of the 12 strains yielding the highest DAG levels (>50 nmol/ml) were isolated from batch culture enrichments run at pH 8.5. We found that the strains capable of producing large amounts of DAG were predominantly Clostridium bifermentans (8 of 12), followed by Escherichia coli (2 of 12). Interestingly, one DAG-producing strain was Bifidobacterium infantis, which is often considered a beneficial gut microorganism. Our results have provided further evidence that fecal bacteria can produce DAG and that specific bacterial groups are involved in this process. Future strategies to reduce DAG formation in the gut should target these species.

* Corresponding author. Mailing address: Food Microbial Sciences Unit, School of Food Biosciences, The University of Reading, Whiteknights, P.O. Box 226, Reading RG6 6AP, United Kingdom. Phone: 44(0)118 935 7136. Fax: 44(0)118 935 7222. E-mail: jvulevic{at}yahoo.com.

Applied and Environmental Microbiology, September 2004, p. 5659-5666, Vol. 70, No. 9
0099-2240/04/$08.00+0     DOI: 10.1128/AEM.70.9.5659-5666.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Depeint, F., Tzortzis, G., Vulevic, J., I'Anson, K., Gibson, G. R (2008). Prebiotic evaluation of a novel galactooligosaccharide mixture produced by the enzymatic activity of Bifidobacterium bifidum NCIMB 41171, in healthy humans: a randomized, double-blind, crossover, placebo-controlled intervention study. Am. J. Clin. Nutr. 87: 785-791 [Abstract] [Full Text]  


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