title: Glutamine, glutamate, and arginine-based acid resistance in Lactobacillus reuteri.
abstract: This study aimed to determine whether glutamine deamidation improves acid resistance of Lactobacillus reuteri, and to assess whether arginine, glutamine, and glutamate-mediated acid resistance are redundant or complementary mechanisms of acid resistance. Three putative glutaminase genes, gls1, gls2, and gls3, were identified in L. reuteri 100-23. All three genes were expressed during growth in mMRS and wheat sourdough. L. reuteri consistently over-expressed gls3 and the glutamate decarboxylase gadB. L. reuteri 100-23ΔgadB over-expressed gls3 and the arginine deiminase gene adi. Analysis of the survival of L. reuteri in acidic conditions revealed that arginine conversion is effective at pH of 3.5 while glutamine or glutamate conversion were effective at pH of 2.5. Arginine conversion increased the pHin but not ΔΨ; glutamate decarboxylation had only a minor effect on the pHin but increased the ΔΨ. This study demonstrates that glutamine deamidation increases the acid resistance of L. reuteri independent of glutamate decarboxylase activity. Arginine and glutamine/glutamate conversions confer resistance to lactate at pH of 3.5 and phosphate at pH of 2.5, respectively. Knowledge of L. reuteri's acid resistance improves the understanding of the adaptation of L. reuteri to intestinal ecosystems, and facilitates the selection of probiotic and starter cultures.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For, Edmonton, AB, Canada T6G 2P5.
authors.forename: Januana S
authors.initials: JS
authors.lastname: Teixeira
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For, Edmonton, AB, Canada T6G 2P5.
authors.forename: Arisha
authors.initials: A
authors.lastname: Seeras
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For, Edmonton, AB, Canada T6G 2P5.
authors.forename: Alma Fernanda
authors.initials: AF
authors.lastname: Sanchez-Maldonado
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For, Edmonton, AB, Canada T6G 2P5.
authors.forename: Chonggang
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For, Edmonton, AB, Canada T6G 2P5.
authors.forename: Marcia Shu-Wei
authors.initials: MS
authors.lastname: Su
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For, Edmonton, AB, Canada T6G 2P5. Electronic address: mgaenzle@ualberta.ca.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Gänzle
mesh_terms: D000143:Acids / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D005972:Glutaminase / Q000235:genetics / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism; D052200:Limosilactobacillus reuteri / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*
chemical_list: D000143:Acids; D001426:Bacterial Proteins; D005973:Glutamine; D018698:Glutamic Acid; D001120:Arginine; D006867:Hydrolases; D005972:Glutaminase; C019723:arginine deiminase; D005968:Glutamate Decarboxylase
keywords: Acid resistance; Arginine deiminase; Glutamate decarboxylase; Glutaminase; Lactobacillus reuteri 100-23