Add reference The present study was initiated to evaluate the quantitative proteomic profiling of Protothecazopfiigenotypes. The cells (P.zopfii genotype 1 –noninfectious and genotype 2 -infectious) were cultured in triplicates until the mid-logarithmic growth phase; the proteins were extracted after sonication on ice, followed by 2D DIGE separation as recommended by the manufacturer (GE Healthcare). The differentially expressed proteins spots were identified using Decodon software analysis (Delta 2D version 4.0 software). Protein identification was carried out by MALDI TOF MS/MS (Ultraflex III TOF/TOF, Bruker Daltonics, Bremen, Germany). The spectra was acquired using the automated option (AutoXecute ) of the Flex Analysis software version 3.3 (Bruker Daltonics, Leipzig, Germany), processed using Flex analysis software version 3.3 (Bruker Daltonics, Leipzig, Germany) and the database search was conducted using the MS/MS ion search (MASCOT, http://www.matrixscience.com) against all entries of NCBInr (GenBank)/Swissprot with subsequent parameters: trypsin digestion, up to one missed cleavage, fixed modifications: carbamidomethyl and with the following variable modifications: oxidation (M), peptide tol.: +- 1.2 Da, MS/MS tol.: +- 0.6 Da, peptide charge: +1. The results were assessed using MOWSE score, p- and E values and those possess positive hits with cRAP database were eliminated from the list.