“…Fig. 6Signal transduction pathways and transcriptional regulators affecting the filamentous growth of dimorphic pathopoiesis fungus in response to environmental conditions, which were reconstructed based on the predicted morphological shift in C. albicans [9, 38, 40, 42]. The red and blue colors highlight the homologous genes significantly up- and down-regulated in T. cutaneum B3.…”
Section: Resultsmentioning
confidence: 99%
“…Another differentially expressed genes are c11060_g1 and c18673_g1 , which were up-regulated at 1.07- and 1.58-folds, respectively, in the yeast-from cells. These genes are homologs to SLN1 and SSK1 in C. albicans , which encode the histidine kinase SLN1 and its regulating protein SSK1 to activate the HOG (high osmolarity glycerol) MAPK pathway through the SLN1 branch for sensing not only osmotic pressure but also other signals, particularly a repression on filamentation for yeast cells to grow with unicellular morphology [40].…”
Background
Compared to the oleaginous yeast
Yarrowia lipolytica
,
Trichosporon cutaneum
can metabolize pentose sugars more efficiently, and in the meantime is more tolerant to inhibitors, which is suitable for lipid production from lignocellulosic biomass. However, this species experiences dimorphic transition between yeast-form cells and hyphae during submerged fermentation, which consequently affects the rheology and mass transfer performance of the fermentation broth and its lipid production.
Results
The strain
T. cutaneum
B3 was cultured with medium composed of yeast extract, glucose and basic minerals. The experimental results indicated that yeast-form morphology was developed when yeast extract was supplemented at 1 g/L, but hyphae were observed when yeast extract supplementation was increased to 3 g/L and 5 g/L, respectively. We speculated that difference in nitrogen supply to the medium might be a major reason for the dimorphic transition, which was confirmed by the culture with media supplemented with yeast extract at 1 g/L and urea at 0.5 g/L and 1.0 g/L to maintain total nitrogen at same levels as that detected in the media with yeast extract supplemented at 3 g/L and 5 g/L. The morphological change of
T. cutaneum
B3 affected not only the content of intracellular lipids but also their composition, due to its impact on the rheology and oxygen mass transfer performance of the fermentation broth, and more lipids with less polyunsaturated fatty acids such as linoleic acid (C18:2) were produced by the yeast-form cells. When
T. cutaneum
B3 was cultured at an aeration rate of 1.5 vvm for 72 h with the medium composed of 60 g/L glucose, 3 g/L yeast extract and basic minerals, 27.1 g (dry cell weight)/L biomass was accumulated with the lipid content of 46.2%, and lipid productivity and yield were calculated to be 0.174 g/L/h and 0.21 g/g, respectively. Comparative transcriptomics analysis identified differently expressed genes for sugar metabolism and lipid synthesis as well as signal transduction for the dimorphic transition of
T. cutaneum
B3.
Conclusions
Assimilable nitrogen was validated as one of the major reasons for the dimorphic transition between yeast-form morphology and hyphae with
T. cutaneum
, and the yeast-form morphology was more suitable for lipid production at high content with less polyunsaturated fatty acids as feedstock for biodiesel production.
Electronic supplementary material
The online version of this article (10.1186/s13068-019-1543-3) contains supplementary material, which is available to authorized users.
“…Fig. 6Signal transduction pathways and transcriptional regulators affecting the filamentous growth of dimorphic pathopoiesis fungus in response to environmental conditions, which were reconstructed based on the predicted morphological shift in C. albicans [9, 38, 40, 42]. The red and blue colors highlight the homologous genes significantly up- and down-regulated in T. cutaneum B3.…”
Section: Resultsmentioning
confidence: 99%
“…Another differentially expressed genes are c11060_g1 and c18673_g1 , which were up-regulated at 1.07- and 1.58-folds, respectively, in the yeast-from cells. These genes are homologs to SLN1 and SSK1 in C. albicans , which encode the histidine kinase SLN1 and its regulating protein SSK1 to activate the HOG (high osmolarity glycerol) MAPK pathway through the SLN1 branch for sensing not only osmotic pressure but also other signals, particularly a repression on filamentation for yeast cells to grow with unicellular morphology [40].…”
Background
Compared to the oleaginous yeast
Yarrowia lipolytica
,
Trichosporon cutaneum
can metabolize pentose sugars more efficiently, and in the meantime is more tolerant to inhibitors, which is suitable for lipid production from lignocellulosic biomass. However, this species experiences dimorphic transition between yeast-form cells and hyphae during submerged fermentation, which consequently affects the rheology and mass transfer performance of the fermentation broth and its lipid production.
Results
The strain
T. cutaneum
B3 was cultured with medium composed of yeast extract, glucose and basic minerals. The experimental results indicated that yeast-form morphology was developed when yeast extract was supplemented at 1 g/L, but hyphae were observed when yeast extract supplementation was increased to 3 g/L and 5 g/L, respectively. We speculated that difference in nitrogen supply to the medium might be a major reason for the dimorphic transition, which was confirmed by the culture with media supplemented with yeast extract at 1 g/L and urea at 0.5 g/L and 1.0 g/L to maintain total nitrogen at same levels as that detected in the media with yeast extract supplemented at 3 g/L and 5 g/L. The morphological change of
T. cutaneum
B3 affected not only the content of intracellular lipids but also their composition, due to its impact on the rheology and oxygen mass transfer performance of the fermentation broth, and more lipids with less polyunsaturated fatty acids such as linoleic acid (C18:2) were produced by the yeast-form cells. When
T. cutaneum
B3 was cultured at an aeration rate of 1.5 vvm for 72 h with the medium composed of 60 g/L glucose, 3 g/L yeast extract and basic minerals, 27.1 g (dry cell weight)/L biomass was accumulated with the lipid content of 46.2%, and lipid productivity and yield were calculated to be 0.174 g/L/h and 0.21 g/g, respectively. Comparative transcriptomics analysis identified differently expressed genes for sugar metabolism and lipid synthesis as well as signal transduction for the dimorphic transition of
T. cutaneum
B3.
Conclusions
Assimilable nitrogen was validated as one of the major reasons for the dimorphic transition between yeast-form morphology and hyphae with
T. cutaneum
, and the yeast-form morphology was more suitable for lipid production at high content with less polyunsaturated fatty acids as feedstock for biodiesel production.
Electronic supplementary material
The online version of this article (10.1186/s13068-019-1543-3) contains supplementary material, which is available to authorized users.
“…In eukaryotes, MAPK signaling transduction pathways mediate this adaptation, leading to specific and adequate responses. The role of the MAP kinase Hog1 in the response to osmotic shock is essential and has been extensively study in S. cerevisiae and other organisms [46][47][48][49]. In C. albicans two MAP kinases, Hog1 and Cek1 have been involved in the response to hyperosmotic conditions [20,21] being the double mutant cek1 hog1 highly hypersensitive to osmostress.…”
As opportunistic pathogen, Candida albicans adapts to different environmental conditions and its corresponding stress. The Hog1 MAPK (Mitogen Activated Protein Kinase) was identified as the main MAPK involved in the response to osmotic stress. It was later shown that this MAPK is also involved in the response to a variety of stresses and therefore, its role in virulence, survival to phagocytes and establishment as commensal in the mouse gastrointestinal tract was reported. In this work, the role of Hog1 in osmotic stress is further analyzed, showing that this MAPK is involved in lipid homeostasis. The hog1 mutant accumulates lipid droplets when exposed to osmotic stress, leading to an increase in cell permeability and delaying the endocytic trafficking routes. Cek1, a MAPK also implicated in the response to osmotic challenge, did not play a role in lipid homeostasis indicating that Hog1 is the main MAP kinase in this response. The alteration on lipid metabolism observed in hog1 mutants is proposed to contribute to the sensitivity to osmotic stress.
“…Importantly, the virulence factors Sap6p and Hyr1p were found to be essential for Ume6p-related inhibition of GI tract colonization (Witchley et al, 2019). As well as these effects in yeast-hyphal transition, fungal MAPK signaling has also been associated with C. albicans gut colonization (Román et al, 2019), not just with virulence (Román et al, 2007). In a recent study, all three MAPK pathways (Mkc1p, Cek1p, and Hog1p) were identified as important for fungal fitness in the gut, but in particular the HOG pathway as null mutants in HOG1 or PBS2 were unable to colonize the GI tract (Prieto et al, 2014).…”
Section: Candida Albicans As An Essential Part Of the Healthy Mycobiotamentioning
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
