Heat and osmotic stress responses of probiotic Lactobacillus rhamnosus HN001 (DR20) in relation to viability after drying

Jaya, R, McJarrow, P and Gopal, P 2003, 'Heat and osmotic stress responses of probiotic Lactobacillus rhamnosus HN001 (DR20) in relation to viability after drying', Applied and Environmental Microbiology, vol. 69, no. 2, pp. 917-925.

Document type: Journal Article
Collection: Journal Articles

Title Heat and osmotic stress responses of probiotic Lactobacillus rhamnosus HN001 (DR20) in relation to viability after drying
Author(s) Jaya, R
McJarrow, P
Gopal, P
Year 2003
Journal name Applied and Environmental Microbiology
Volume number 69
Issue number 2
Start page 917
End page 925
Total pages 9
Publisher American Society for Microbiology
Abstract The viability of lactic acid bacteria in frozen, freeze-dried, and air-dried forms is of significant commercial interest to both the dairy and food industries. In this study we observed that when prestressed with either heat (50ºC) or salt (0.6 M NaCl), Lactobacillus rhamnosus HN001 (also known as DR20) showed significant (P < 0.05) improvement in viability compared with the nonstressed control culture after storage at 30ºC in the dried form. To investigate the mechanisms underlying this stress-related viability improvement in L. rhamnosus HN001, we analyzed protein synthesis in cultures subjected to different growth stages and stress conditions, using two-dimensional gel electrophoresis and N-terminal sequencing. Several proteins were up- or down-regulated after either heat or osmotic shock treatments. Eleven proteins were positively identified, including the classical heat shock proteins GroEL and DnaK and the glycolytic enzymes glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, enolase, phosphoglycerate kinase, and triose phosphate isomerase, as well as tagatose 1,6-diphosphate aldolase of the tagatose pathway. The phosphocarrier protein HPr (histidine-containing proteins) was up-regulated in cultures after the log phase irrespective of the stress treatments used. The relative synthesis of an ABC transport-related protein was also up-regulated after shock treatments. Carbohydrate analysis of cytoplasmic contents showed higher levels (20 ± 3 μg/mg of protein) in cell extracts (CFEs) derived from osmotically stressed cells than in the unstressed control (15 ± 3 μg/mg of protein). Liquid chromatography of these crude carbohydrate extracts showed significantly different profiles. Electrospray mass spectrometry analysis of CFEs revealed, in addition to normal mono-, di-, tri-, and tetrasaccharides, the presence of saccharides modified with glycerol.
Subject Biochemistry and Cell Biology not elsewhere classified
Keyword(s) amino acid sequence
amino terminal sequence
bacterial growth
bacterium culture
cell viability
comparative study
controlled study
down regulation
gel electrophoresis
growth curve
heat shock
industrial production
Lactobacillus rhamnosus
liquid chromatography
mass spectrometry
osmotic stress
protein analysis
protein synthesis
statistical analysis
statistical significance
DOI - identifier 10.1128/AEM.69.2.917-925.2003
ISSN 0099-2240
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