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osu1124142014.pdf (909.87 KB)
ETD Abstract Container
Abstract Header
Gluconate metabolism in
Lactobacillus
and its role in persistence in the human intestine
Author Info
Jenkins, Julie Kay
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=osu1124142014
Abstract Details
Year and Degree
2005, Doctor of Philosophy, Ohio State University, Food Science and Nutrition.
Abstract
The demand for foods that provide a health benefit beyond basic nutrition is on the rise. Prebiotics are non-viable food components that promote growth of a number of beneficial bacteria that naturally inhabit the human intestine. Some of these beneficial bacteria, such as
Lactobacillus
and
Bifidobacterium
species, are capable of eliciting health benefits such as reduced incidence of lactose intolerance and diarrhea, improved immune response and reduced cancer risk. The present studies address the effect of gluconate, a component of many foods and food supplements, on human intestinal microflora. Genes involved in gluconate metabolism in
Lactobacillus reuteri
were characterized. The effect of dietary gluconate supplementation on human intestinal populations of
Lactobacillus, Bifidobacterium, Propionibacterium
, and
Escherchia coli
was assessed over a 7-week period. Weekly stool samples were collected from 12 subjects and selected bacterial populations were enumerated. Colonies were subsequently grown on medium containing glucose or gluconate as the primary carbon source. At the level tested, dietary calcium gluconate did not significantly affect the overall quantity of
Lactobacillus, Bifidobacterium, E. coli
or
Propionibacterium
in most of the subjects tested. However, the proportion of gluconate-fermenting
Lactobacillus
and
Propionibacterium
strains increased upon gluconate consumption in some subjects, suggesting that a shift in species composition may occur. Speciation using the 16S-23S rRNA intergenic spacer region showed 2-6 different gluconate-fermenting
Lactobacillus
species in each subject and 11 different species overall. A 500 base pair (bp) putative gluconate kinase and a 750 bp putative gluconate permease fragments were found in the
Lactobacillus reuteri
100-23 genome by amplifying DNA with degenerate primers. A gluconate-negative mutant of
L. reuteri
100-23 was constructed via homologous recombination utilizing the putative gluconate permease fragment. The mutant (100-23D) and wild-type strains were characterized for gluconokinase, 6-phosphogluconate dehydrogenase and gluconate uptake activities. The mutant had significantly lower gluconokinase and gluconate uptake activities compared to wild-type. This suggests that gluconate genes in
L. reuteri
100-23 are induced by gluconate and potentially arranged in an operon. Transcriptional analysis of wild-type and mutant strains showed a single transcript, indicating the gluconate permease gene is constitutively transcribed, and not inducible, in the presence of glucose or gluconate.
Committee
Ahmed Yousef (Advisor)
Keywords
Lactobacillus
;
gluconate
;
human intestinal microflora
Recommended Citations
Refworks
EndNote
RIS
Mendeley
Citations
Jenkins, J. K. (2005).
Gluconate metabolism in
Lactobacillus
and its role in persistence in the human intestine
[Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1124142014
APA Style (7th edition)
Jenkins, Julie.
Gluconate metabolism in
Lactobacillus
and its role in persistence in the human intestine.
2005. Ohio State University, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=osu1124142014.
MLA Style (8th edition)
Jenkins, Julie. "Gluconate metabolism in
Lactobacillus
and its role in persistence in the human intestine." Doctoral dissertation, Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1124142014
Chicago Manual of Style (17th edition)
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Document number:
osu1124142014
Download Count:
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Copyright Info
© 2005, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.