title: Proteomic comparison of the probiotic bacterium Lactobacillus casei Zhang cultivated in milk and soy milk.
abstract: Soy milk is regarded as a substitute for milk and has become popular in varied diets throughout the world. It has been shown that a newly characterized probiotic bacterium (Lactobacillus casei Zhang) actually grows faster in soy milk than in bovine milk. To elucidate the mechanism involved, we carried out a proteomic analysis to characterize bacterial proteins that varied upon growth in soy milk and bovine milk at 3 different growth phases, and compare their expression under these conditions. A total of 104 differentially expressed spots were identified from different phases using a peptide mass fingerprinting assay. Functional analysis revealed that a major part of these identified proteins is associated with transport and metabolism of carbohydrates, nucleotides, and amino acids as well. The results from our proteomic analysis were clarified by real-time quantitative PCR assay, which showed that Lb. casei Zhang loci involved in purine and pyrimidine biosynthesis were transcriptionally enhanced during growth in soy milk at lag phase (pH 6.4), whereas the loci involved in carbohydrate metabolism were upregulated in bovine milk. Particularly, our results showed that l-glutamine might play an important role in the growth of Lb. casei Zhang in soy milk and bovine milk, perhaps by contributing to purine, pyrimidine, and amino sugar metabolism.
authors.affiliation: Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Huhhot, Inner Mongolia, P R China.
authors.forename: Jicheng
authors.initials: J
authors.lastname: Wang
authors.forename: Rina
authors.initials: R
authors.lastname: Wu
authors.forename: Wenyi
authors.initials: W
authors.lastname: Zhang
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Sun
authors.forename: Wenjing
authors.initials: W
authors.lastname: Zhao
authors.forename: Heping
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D007780:Lacticaseibacillus casei / Q000235:genetics* / Q000254:growth & development; D008892:Milk / Q000737:chemistry / Q000382:microbiology*; D040901:Proteomics; D060888:Real-Time Polymerase Chain Reaction; D041942:Soy Milk / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins
keywords: 2-dimensional electrophoresis; Lactobacillus casei Zhang; growth in milk and soy milk; proteomic analysis