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Physiological and Transcriptional Response of Lactobacillus casei ATCC 334 to Acid Stress

Physiological and Transcriptional Response of Lactobacillus casei ATCC 334 to Acid Stress Physiological and Transcriptional Response of Lactobacillus casei ATCC 334 to Acid Stress ▿ † § Jeff R. Broadbent 1 , * , Rebecca L. Larsen 1 , Virginia Deibel 2 , ‡ , and James L. Steele 2 1 Department of Nutrition, Dietetics, and Food Science, Utah State University, Logan, Utah 2 Department of Food Science, University of Wisconsin—Madison, Madison, Wisconsin ABSTRACT This study investigated features of the acid tolerance response (ATR) in Lactobacillus casei ATCC 334. To optimize ATR induction, cells were acid adapted for 10 or 20 min at different pH values (range, 3.0 to 5.0) and then acid challenged at pH 2.0. Adaptation over a broad range of pHs improved acid tolerance, but the highest survival was noted in cells acid adapted for 10 or 20 min at pH 4.5. Analysis of cytoplasmic membrane fatty acids (CMFAs) in acid-adapted cells showed that they had significantly ( P < 0.05) higher total percentages of saturated and cyclopropane fatty acids than did control cells. Specifically, large increases in the percentages of C 14:0 , C 16:1n(9) , C 16:0 , and C 19:0(11c) were noted in the CMFAs of acid-adapted and acid-adapted, acid-challenged cells, while C 18:1n(9) and C 18:1n(11) showed the greatest decrease. Comparison of the transcriptome from control cells (grown at pH 6.0) against that from cells acid adapted for 20 min at pH 4.5 indicated that acid adaption invoked a stringent-type response that was accompanied by other functions which likely helped these cells resist acid damage, including malolactic fermentation and intracellular accumulation of His. Validation of microarray data was provided by experiments that showed that L. casei survival at pH 2.5 was improved at least 100-fold by chemical induction of the stringent response or by the addition of 30 mM malate or 30 mM histidine to the acid challenge medium. To our knowledge, this is the first report that intracellular histidine accumulation may be involved in bacterial acid resistance. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Bacteriology American Society For Microbiology

Physiological and Transcriptional Response of Lactobacillus casei ATCC 334 to Acid Stress

Physiological and Transcriptional Response of Lactobacillus casei ATCC 334 to Acid Stress

Journal of Bacteriology , Volume 192 (9): 2445 – May 1, 2010

Abstract

Physiological and Transcriptional Response of Lactobacillus casei ATCC 334 to Acid Stress ▿ † § Jeff R. Broadbent 1 , * , Rebecca L. Larsen 1 , Virginia Deibel 2 , ‡ , and James L. Steele 2 1 Department of Nutrition, Dietetics, and Food Science, Utah State University, Logan, Utah 2 Department of Food Science, University of Wisconsin—Madison, Madison, Wisconsin ABSTRACT This study investigated features of the acid tolerance response (ATR) in Lactobacillus casei ATCC 334. To optimize ATR induction, cells were acid adapted for 10 or 20 min at different pH values (range, 3.0 to 5.0) and then acid challenged at pH 2.0. Adaptation over a broad range of pHs improved acid tolerance, but the highest survival was noted in cells acid adapted for 10 or 20 min at pH 4.5. Analysis of cytoplasmic membrane fatty acids (CMFAs) in acid-adapted cells showed that they had significantly ( P < 0.05) higher total percentages of saturated and cyclopropane fatty acids than did control cells. Specifically, large increases in the percentages of C 14:0 , C 16:1n(9) , C 16:0 , and C 19:0(11c) were noted in the CMFAs of acid-adapted and acid-adapted, acid-challenged cells, while C 18:1n(9) and C 18:1n(11) showed the greatest decrease. Comparison of the transcriptome from control cells (grown at pH 6.0) against that from cells acid adapted for 20 min at pH 4.5 indicated that acid adaption invoked a stringent-type response that was accompanied by other functions which likely helped these cells resist acid damage, including malolactic fermentation and intracellular accumulation of His. Validation of microarray data was provided by experiments that showed that L. casei survival at pH 2.5 was improved at least 100-fold by chemical induction of the stringent response or by the addition of 30 mM malate or 30 mM histidine to the acid challenge medium. To our knowledge, this is the first report that intracellular histidine accumulation may be involved in bacterial acid resistance.

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Publisher
American Society For Microbiology
Copyright
Copyright © 2010 by the American society for Microbiology.
ISSN
0021-9193
eISSN
1098-5530
DOI
10.1128/JB.01618-09
pmid
20207759
Publisher site
See Article on Publisher Site

Abstract

Physiological and Transcriptional Response of Lactobacillus casei ATCC 334 to Acid Stress ▿ † § Jeff R. Broadbent 1 , * , Rebecca L. Larsen 1 , Virginia Deibel 2 , ‡ , and James L. Steele 2 1 Department of Nutrition, Dietetics, and Food Science, Utah State University, Logan, Utah 2 Department of Food Science, University of Wisconsin—Madison, Madison, Wisconsin ABSTRACT This study investigated features of the acid tolerance response (ATR) in Lactobacillus casei ATCC 334. To optimize ATR induction, cells were acid adapted for 10 or 20 min at different pH values (range, 3.0 to 5.0) and then acid challenged at pH 2.0. Adaptation over a broad range of pHs improved acid tolerance, but the highest survival was noted in cells acid adapted for 10 or 20 min at pH 4.5. Analysis of cytoplasmic membrane fatty acids (CMFAs) in acid-adapted cells showed that they had significantly ( P < 0.05) higher total percentages of saturated and cyclopropane fatty acids than did control cells. Specifically, large increases in the percentages of C 14:0 , C 16:1n(9) , C 16:0 , and C 19:0(11c) were noted in the CMFAs of acid-adapted and acid-adapted, acid-challenged cells, while C 18:1n(9) and C 18:1n(11) showed the greatest decrease. Comparison of the transcriptome from control cells (grown at pH 6.0) against that from cells acid adapted for 20 min at pH 4.5 indicated that acid adaption invoked a stringent-type response that was accompanied by other functions which likely helped these cells resist acid damage, including malolactic fermentation and intracellular accumulation of His. Validation of microarray data was provided by experiments that showed that L. casei survival at pH 2.5 was improved at least 100-fold by chemical induction of the stringent response or by the addition of 30 mM malate or 30 mM histidine to the acid challenge medium. To our knowledge, this is the first report that intracellular histidine accumulation may be involved in bacterial acid resistance.

Journal

Journal of BacteriologyAmerican Society For Microbiology

Published: May 1, 2010

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