title: Pichia fermentans dimorphic changes depend on the nitrogen source.
abstract: Pichia fermentans DiSAABA 726 is a biofilm-forming yeast that undergoes dimorphic transition. Under yeast-like morphology it controls brown rot caused by Monilia spp. on apple fruit, while under pseudohyphal form, it shows pathogenic behaviour itself on peach fruit. The present study investigates the nutritional factors that induce and separate yeast-like and pseudohyphal morphologies under laboratory conditions. We show that P. fermentans DiSAABA 726 produces mainly yeast-like cells on media containing millimolar concentrations of urea and diammonium phosphate, and forms pseudohyphae at micromolar concentrations of these two salts. With ammonium sulphate, yeast-like or pseudohyphal morphology depends on the N concentration and the pH of the culture media. Amino acids such as methionine, valine, and phenylalanine invariably induce pseudohyphal morphology irrespective of the N concentration and the pH of the culture media. Methionol, 1-butanol, isobutanol, and isopropanol induce pseudohyphal growth, while phenylethanol and isoamyl alcohol fail to induce the formation of filaments. Thus, the morphogenesis of P. fermentans DiSAABA 726 depends more on the nitrogen source than on the N concentration, and is regulated by the quorum-sensing molecules that are generally produced from amino-acid assimilation under nitrogen starvation.
authors: Dipartimento di Agraria, Università degli Studi di Sassari, Viale Italia 39, 07100 Sassari, Italy.
authors: Maria Lina
authors: ML
authors: Sanna
authors: Severino
authors: S
authors: Zara
authors: Giacomo
authors: G
authors: Zara
authors: Quirico
authors: Q
authors: Migheli
authors: Marilena
authors: M
authors: Budroni
authors: Ilaria
authors: I
authors: Mannazzu
mesh_terms: D000438:Alcohols / Q000378:metabolism; D000645:Ammonium Sulfate / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D025301:Hyphae / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism* / Q000472:pathogenicity; D009584:Nitrogen / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010843:Pichia / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism* / Q000472:pathogenicity; D014508:Urea / Q000378:metabolism
chemical_list: D000438:Alcohols; D003470:Culture Media; D010710:Phosphates; C024788:ammonium phosphate; D014508:Urea; D009584:Nitrogen; D000645:Ammonium Sulfate