Proteome changes during yeast-like and pseudohyphal growth in the biofilm-forming yeast Pichia fermentans

The Pichia fermentans strain DISAABA 726 is a biofilm-forming yeast that has been proposed as biocontrol agent to control brown rot on apple. However, when inoculated on peach, strain 726 shows yeast-like to pseudohyphal transition coupled to a pathogenic behaviour. To identify the proteins potentially involved in such transition process, a comparative proteome analysis of P. fermentans 726 developed on peach (filamentous growth) vs apple (yeast-like growth) was carried out using two-dimensional gel electrophoresis (2 DE) coupled with mass spectrometry analysis. The proteome comparison was also performed between the two different cell morphologies induced in a liquid medium amended with urea (yeast-like cells) or methionine (filamentous cells) to exclude fruit tissue impact on the transition. Seventy-three protein spots showed significant variations in abundance (± 2 fold, p < 0.01, confidence intervals 99%) between pseudohyphal vs yeast-like morphology produced on fruits. Among them, thirty proteins changed their levels when the two morphologies were developed in liquid medium. The identified proteins belong to several pathways and functions, such as glycolysis, amino acid synthesis, chaperones and signalling transduction. The possible role of a group of proteins belonging to the carbohydrate pathway in the metabolic re-organization during P. fermentans dimorphic transition is discussed.