2026-09-21T23:02:21Zhttps://helda.helsinki.fi/server/oai/request

oai:helda.helsinki.fi:10138/349412026-07-22T11:41:01Zcom_10138_18086com_10138_17738col_10138_18092

Helsingin yliopisto, Maatalous-metsätieteellinen tiedekunta, Elintarvike- ja ympäristötieteiden laitos University of Helsinki, Faculty of Agriculture and Forestry, Department of Food and Environmental Sciences Helsingfors universitet, Agrikultur- och forstvetenskapliga fakulteten, Institutionen för livsmedels- och miljövetenskaper Prodan, Andrei Varmanen, Pekka 2012 URN:NBN:fi:hulib-201507211933 http://hdl.handle.net/10138/34941 The literature review describes the characteristics, uses and probiotic potential of propionibacteria and gives an overview of proteomic methods focusing on 2-DE studies related to probiotic bacteria and P. freudenreichii. The aim of the experimental part was to use 2-DE to obtain proteome maps of two strains of P. freudenreichii and detect inter-strain differential protein expression. The influence of a number of parameters on the quality of 2-D gels was also investigated. The pH 3-7 and pH 3-11 NL proteome maps obtained displayed 305 and 356 spots, respectively, and detected the differential expression of 60 and 72 spots, respectively. The 3-11 NL proteome map showed spot over-crowding in the pH 4-6 region. Addition of 50 mM dithiothreitol (DTT) to the samples prior to isoelectric focusing (IEF) and an increase of IPG buffer concentration greatly improved spot resolution. Silver staining achieved higher spot counts than Coomassie staining. The influence of the number of lysis cycles on protein extraction was marginal, while lower protein sample loads produced superior 2-D gels. Results show that data from 2-DE proteome maps can provide an overview of inter-strain differential protein expression in P. freudenreichii. The optimal 2-DE experimental setup would include pH 4-7 IPG strips, a low protein load and inclusion of DTT in the IEF sample, as well as silver staining for spot visualisation. eng Helsingfors universitet University of Helsinki Helsingin yliopisto 2-DE proteomic probiotic Swiss cheese vitamin B12 Propionibacterium freudenreichii Livsmedelsteknologi Food Technology Elintarviketeknologia Gel-based proteomic comparison of two strains of Propionibacterium freudenreichii ssp. shermanii pro gradu-avhandlingar pro gradu -tutkielmat master's thesis URN:NBN:fi:hulib-201507211933 open.access