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Lactobacillus casei combats acid stress by maintaining cell membrane functionality.
MedLine Citation:
PMID:  22366811     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Lactobacillus casei strains have traditionally been recognized as probiotics and frequently used as adjunct culture in fermented dairy products where lactic acid stress is a frequently encountered environmental condition. We have investigated the effect of lactic acid stress on the cell membrane of L. casei Zhang [wild type (WT)] and its acid-resistant mutant Lbz-2. Both strains were grown under glucose-limiting conditions in chemostats; following challenge by low pH, the cell membrane stress responses were investigated. In response to acid stress, cell membrane fluidity decreased and its fatty acid composition changed to reduce the damage caused by lactic acid. Compared with the WT, the acid-resistant mutant exhibited numerous survival advantages, such as higher membrane fluidity, higher proportions of unsaturated fatty acids, and higher mean chain length. In addition, cell integrity analysis showed that the mutant maintained a more intact cellular structure and lower membrane permeability after environmental acidification. These results indicate that alteration in membrane fluidity, fatty acid distribution, and cell integrity are common mechanisms utilized by L. casei to withstand severe acidification and to reduce the deleterious effect of lactic acid on the cell membrane. This detailed comparison of cell membrane responses between the WT and mutant add to our knowledge of the acid stress adaptation and thus enable new strategies to be developed aimed at improving the industrial performance of this species under acid stress.
Authors:
Chongde Wu; Juan Zhang; Miao Wang; Guocheng Du; Jian Chen
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-2-26
Journal Detail:
Title:  Journal of industrial microbiology & biotechnology     Volume:  -     ISSN:  1476-5535     ISO Abbreviation:  -     Publication Date:  2012 Feb 
Date Detail:
Created Date:  2012-2-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9705544     Medline TA:  J Ind Microbiol Biotechnol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, People's Republic of China.
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