Item – Theses Canada

OCLC number
1019472573
Link(s) to full text
LAC copy
Author
Su, Shu-Wei.
Title
Factors contributing to the competitiveness of Lactobacillus reuteri in sourdough and rodent gut.
Degree
Ph. D. -- University of Alberta, 2011
Publisher
Ottawa : Library and Archives Canada = Bibliothèque et Archives Canada, 2013.
Description
1 online resource
Notes
Includes bibliographical references.
Abstract
<?Pub Inc> 'Lactobacillus reuteri' is a common organism in cereal-based foods and a gut symbiont in humans and animals, yet the molecular mechanisms allowing its persistence in various niches are not well understood. ' L. reuteri' LTH2584 produces reutericyclin and persists in industrial sourdoughs, where acidic conditions during fermentation cause acid stress to organisms. Another strain, 'L. reuteri' 100-23, colonizes the murine forestomach, where this type of lactobacilli contributes to digesta preservation through acid production. 'L. reuteri' LTH2584 and 100-23 were studied to gain an understanding of the phylogenetic relationship between these two isolates, as well as the acid resistance mechanisms and the two-component systems that contribute to the persistence of 'L. reuteri' in sourdough and the murine gut. Analysis of genomic content revealed a close evolutionary relationship between the 'L. reuteri ' isolates from sourdough and rodent gut. In addition, a novel double crossover method was developed to generate isogenic deletion mutants for the evaluation of competitiveness, while the acid resistance mechanism was assessed by disruption of glutamate decarboxylase ('gadB') in ' L. reuteri' 100-23. Glutamate decarboxylase enhanced the ability of ' L. reuteri' to adapt to both acidic environments ('in vitro ') and sourdough fermentations ('in vivo') by decarboxylation of glutamate to [gamma]-aminobutyric acid. Biofilm formation may depend on the cross-communication of the 'hk430' and 'cemAKR' operons. Several osmoregulatory genes that may also be associated with cell envelope architecture and cell morphology were also identified.
ISBN
9780494894392
0494894393
9780494894392