Pichia fermentans dimorphic changes depend on the nitrogen source

• Published in: Fungal biology Vol. 116; no. 7; pp. 769 - 777
• Main Authors: Sanna, Maria Lina, Zara, Severino, Zara, Giacomo, Migheli, Quirico, Budroni, Marilena, Mannazzu, Ilaria
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.07.2012
• Subjects: Alcohols - metabolism; ammonium sulfate; Ammonium Sulfate - metabolism; apples; Biofilm; culture media; Culture Media - chemistry; diammonium phosphate; Hydrogen-Ion Concentration; Hyphae - cytology; Hyphae - growth & development; Hyphae - metabolism; Hyphae - pathogenicity; isoamyl alcohol; isopropyl alcohol; methionine; Monilia; morphogenesis; nitrogen; Nitrogen - metabolism; nitrogen content; Nitrogen starvation; peaches; phenylalanine; Phosphates - metabolism; Pichia - cytology; Pichia - growth & development; Pichia - metabolism; Pichia - pathogenicity; Pichia fermentans; Pseudohyphae; quorum sensing; starvation; urea; Urea - metabolism; valine; Yeast morphogenesis; yeasts; Biofilm; Pichia fermentans; Yeast morphogenesis; Pseudohyphae; Nitrogen starvation
• ISSN: 1878-6146; 1878-6162
• DOI: 10.1016/j.funbio.2012.04.008

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. ► Pichia fermentans is biofilm-forming yeast. ► P. fermentans reversibly changes cell morphology in response to nitrogen source and availability. ► Nitrogen starvation results in pseudohyphal growth. ► Equimolar amounts of N induce yeast-like or pseudohyphal growth depending on the nitrogen source. ► Yeast morphogenesis is regulated by quorum-sensing molecules produced under nitrogen starvation.