Browsing by Subject "aerobic"

The scientific data has demonstrated that surface-associated proteins have a significant role affecting the adaptation to GIT environment, adherence to the intestinal mucus and other potential health benefits occurring through cross-talk of propionibacteria and the host. The reported achievements on the complementary proteomic approaches optimize the accuracy of surface protein identification and surface proteins related to anti-inflammatory activities and adhesion has been identified from Propionibacterium freudenreichii strains. Thus, the aim of this thesis was to compare the effect of atmospheric conditions on surfaceome expression of the P. freudenreichii type strain DSM 20271. Bacterial cultures cultivated in aerobic and anaerobic atmosphere were harvested at the mid-exponential phase of growth. Samples were subjected to gel-free proteomic analysis, based on direct analysis of peptides acquired by trypsin cell-surface shaving followed by identification of released surface-attached proteins and peptides using LC-MS/MS and label-free quantification. It was demonstrated in this work that different atmospheric conditions highly influenced the protein expression patterns. Overall, the expression of more than a hundred proteins were affected by the change of environmental condition, of which the majority were predicted not to include either classical nor non-classical secretion motifs. It is still unresolved question if these cytoplasmic proteins in the shaved-fraction could be transported to the bacterial surface area by uncharacterized mechanisms to serve a specific moonlighting function. Few of the identified proteins, most of which were up-regulated in aerobic growth condition, were already described in other bacterial species to be involved with general stress response (ClpP, ClpB, and Ctc) and reduction of reactive oxygen species (Tpx, AhpC, and AhpF).