Abstract
ABSTRACTTrichosporon cutaneum is able to metabolize high hydrophobic natural compounds such as fatty acids and also can be used as an effective biodegrader to remove a number of toxic aromatic compounds from the environment. However, its growth characteristics were poorly investigated and no yeast–mycelium dimorphism process has been established yet. In the present study, we provided first insights into the effect of nitrogen sources, carbon source, and amino acids together with pH and temperature on morphological switch of T. cutaneum B3. The results showed under close to neutral or weakly alkaline pH conditions, T. cutaneum B3 produced mostly yeast-like cells; while under acidic pH conditions, it produced mostly hyphal-like cells. Under buffered conditions, low nitrogen concentration (<0.2%) would facilitate T. cutaneum B3 to produce yeast-like cells, while the presence of relative high nitrogen concentration (>1%) would induce hyphal-like cells. Under non-buffered conditions, ammonium sulphate, diammonium phosphate, urea and N-acetylglucosamine may via alteration of environmental pH affect yeast–mycelium dimorphism transitions. Methionine, tryptophan and histidine invariably induce pseudohyphal or hyphal morphology. 25 and 28 °C can promote yeast-like cells growth, while cultivated at 37 °C can induce hyphal-like cells growth. Thus, the nitrogen source, alteration of environmental pH and temperature of cultivation played an important role in inducing yeast–mycelium dimorphism transition. Our study confirms the yeast–mycelium dimorphism process of T. cutaneum B3 and highlights that it seems to be a suitable yeast model for further molecular genetics investigation of dimorphism and applications in fermentation morphology engineering.
Highlights
Dimorphism is a peculiar characteristic of several yeast species and filamentous fungi, such as Candida albicans, Saccharomyces cerevisiae, Yarrowia lypolitica, Pichia fermentans, Schizosaccharomyces japonicus, Ustilago maydis, Ophiostoma floccosum, Ceratocystis ulmi, Mycosphaerella graminicola, which can switch between unicellular yeast and multicellular filamentous growth forms in response to changing environmental cues [1,2,3,4,5,6,7,8]
Previous studies reported that the yeast– mycelium dimorphism transition of fungal might be functional and played an important role in their coping with nutrient starvation or other environmental stress, there is increasing evidence that dimorphism may be related to virulence and pathogenicity in several fungal pathogens of plants and animals [3,9,10,11]
Preliminary studies of the morphology of T. cutaneum strain cultivated on yeast extract peptone dextrose medium (YEPD)
Summary
Dimorphism is a peculiar characteristic of several yeast species and filamentous fungi, such as Candida albicans, Saccharomyces cerevisiae, Yarrowia lypolitica, Pichia fermentans, Schizosaccharomyces japonicus, Ustilago maydis, Ophiostoma floccosum, Ceratocystis ulmi, Mycosphaerella graminicola, which can switch between unicellular yeast and multicellular filamentous growth forms in response to changing environmental cues [1,2,3,4,5,6,7,8]. In C. albicans, alterations in pH, high temperature, nutrient deprivation and addition of serum or N-acetylglucosamine are the most commonly environmental cues which can induce its morphology to change from round budding cells to elongated hyphae or filamentous growth and show pathogenic trait to mammals [2,13]. In order to facilitate better control of morphology switch
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