High-resolution mass spectrometry-based global proteomic analysis of probiotic strains Lactobacillus fermentum NCDC 400 and RS2

Lactobacillus fermentum strains NCDC 400 and RS2, previously isolated from dairy sources, exhibited excellent probiotic properties were studied for the global proteomic profile. A total of 1125 proteins were identified by a high-resolution mass spectrometer, ESI-qTOF (nano-LC-MS/MS) in the strains of L. fermentum. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis resulted in 60.9% and 59.2% of the total proteins were functionally annotated for NCDC 400 and RS2 respectively. Simultaneously, a cluster of orthologous groups (COGs) and KEGG together revealed the presence of a significant number of proteins involved in transcription, translation, chaperones, peptidoglycan biosynthesis, nucleotide, amino acid and carbohydrate metabolism. Most of the proteins that play a vital role in the formation of RNA polymerase, ribosomal subunits, and aminoacyl-tRNA biosynthesis were fully mapped. Further analysis by bioinformatics tools revealed that 13.83% of the proteins were hydrophobic while 86.17% were hydrophilic in nature. The present findings represent the first draft proteome map of L. fermentum strains and demonstrate the involvement of important proteins in normal physiology and growth of potential probiotic strain.