Applied Microbiology and Biotechnology

, Volume 93, Issue 2, pp 707–722

A combined physiological and proteomic approach to reveal lactic-acid-induced alterations in Lactobacillus casei Zhang and its mutant with enhanced lactic acid tolerance

Genomics, transcriptomics, proteomics

DOI: 10.1007/s00253-011-3757-6

Cite this article as:
Wu, C., Zhang, J., Chen, W. et al. Appl Microbiol Biotechnol (2012) 93: 707. doi:10.1007/s00253-011-3757-6

Abstract

Lactobacillus casei has traditionally been recognized as a probiotic and frequently used as an adjunct culture in fermented dairy products, where acid stress is an environmental condition commonly encountered. In the present study, we carried out a comparative physiological and proteomic study to investigate lactic-acid-induced alterations in Lactobacillus casei Zhang (WT) and its acid-resistant mutant. Analysis of the physiological data showed that the mutant exhibited 33.8% higher glucose phosphoenolpyruvate:sugar phosphotransferase system activity and lower glycolytic pH compared with the WT under acidic conditions. In addition, significant differences were detected in both cells during acid stress between intracellular physiological state, including intracellular pH, H+-ATPase activity, and intracellular ATP pool. Comparison of the proteomic data based on 2D-DIGE and i-TRAQ indicated that acid stress invoked a global change in both strains. The mutant protected the cells against acid damage by regulating the expression of key proteins involved in cellular metabolism, DNA replication, RNA synthesis, translation, and some chaperones. Proteome results were validated by Lactobacillus casei displaying higher intracellular aspartate and arginine levels, and the survival at pH 3.3 was improved 1.36- and 2.10-fold by the addition of 50-mM aspartate and arginine, respectively. To our knowledge, this is the first demonstration that aspartate may be involved in acid tolerance in Lactobacillus casei. Results presented here may help us understand acid resistance mechanisms and help formulate new strategies to enhance the industrial applications of this species.

Keywords

Acid stressLactobacillus casei2D-DIGEi-TRAQPhysiological analysis

Supplementary material

253_2011_3757_MOESM1_ESM.doc (426 kb)
Fig. S12D-gels for spot-picker. A total of 1200 μμg of protein was focused on 24 cm pH 4–7 IEF strips and stained with Coomassie blue R-250. Indicated protein spots were picked and subjected to in-gel digestion and mass spectrometry. (DOC 426 kb)
253_2011_3757_MOESM2_ESM.doc (311 kb)
Fig. S2Hierarchical clustering of proteomic data arranged by functional categories according to the COG classification. C, Energy production and conversion; D, Cell-cycle control, mitosis and meiosis; E, Amino acid transporter and metabolism; F, Nucleotide transport and metabolism; G, Carbohydrate transport and metabolism; H, Coenzyme transport and metabolism; I, Lipid transport and metabolism; J, Translation, ribosomal structure and biogenesis; K, Transcription; L, Replication recombination and repair; M, Cell wall/membrane biogenesis; O, Posttranslational modification, protein turnover, chaperones; P, Inorganic ion transport and metabolism; R, General function prediction only; UN, Function unknown and not in COG. (DOC 311 kb)

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  1. 1.Key Laboratory of Industrial Biotechnology, Ministry of Education, and School of BiotechnologyJiangnan UniversityWuxiPeople’s Republic of China
  2. 2.State Key Laboratory of Food Science and TechnologyJiangnan UniversityWuxiPeople’s Republic of China
  3. 3.School of Food Science and TechnologyJiangnan UniversityWuxiPeople’s Republic of China