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Diversity and mechanisms of alkali tolerance in lactobacilli

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Title: Diversity and mechanisms of alkali tolerance in lactobacilli
Authors: Sawatari, Yuki Browse this author
Yokota, Atsushi2 Browse this author →KAKEN DB
Authors(alt): 横田, 篤2
Issue Date: Jun-2007
Publisher: American Society for Microbiology
Journal Title: Applied and Environmental Microbiology
Volume: 73
Issue: 12
Start Page: 3909
End Page: 3915
Publisher DOI: 10.1128/AEM.02834-06
PMID: 17449704
Abstract: We determined the maximum pH that allows growth (pHmax) for 34 strains of lactobacilli. High alkali tolerance was exhibited by strains of Lactobacillus casei, L. paracasei subsp. tolerans, L. paracasei subsp. paracasei, L. curvatus, L. pentosus, and L. plantarum that originated from plant material, with pHmax values between 8.5 and 8.9. Among these, L. casei NRIC 1917 and L. paracasei subsp. tolerans NRIC 1940 showed the highest pHmax, at 8.9. Digestive tract isolates of L. gasseri, L. johnsonii, L. reuteri, L. salivarius subsp. salicinius, and L. salivarius subsp. salivarius exhibited moderate alkali tolerance, with pHmax values between 8.1 and 8.5. Dairy isolates of L. delbrueckii subsp. bulgaricus, L. delbrueckii subsp. lactis, and L. helveticus exhibited no alkali tolerance, with pHmax values between 6.7 and 7.1. Measurement of the internal pH of representative strains revealed the formation of transmembrane proton gradients (pH) in a reversed direction (i.e., acidic interior) at alkaline external-pH ranges, regardless of their degrees of alkali tolerance. Thus, the reversed pH did not determine alkali tolerance diversity. However, the pH contributed to alkali tolerance, as the pHmax values of several strains decreased with the addition of nigericin, which dissipates pH. Although neutral external-pH values resulted in the highest glycolysis activity in the presence of nigericin regardless of alkali tolerance, substantial glucose utilization was still detected in the alkali-tolerant strains, even in a pH range of between 8.0 and 8.5, at which the remaining strains lost most activity. Therefore, the alkali tolerance of glycolysis reactions contributes greatly to the determination of alkali tolerance diversity.
Rights: Copyright © American Society for Microbiology.
Type: article
Appears in Collections:農学院・農学研究院 (Graduate School of Agriculture / Faculty of Agriculture) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 横田 篤

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