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Abstract Background Microbial oil is one important bio-product for its important function in energy, chemical, and food industry. Finding suitable substrates is one key issue for its industrial application. Both hydrophilic and hydrophobic substrates can be utilized by oleaginous microorganisms with two different bio-pathways (“de novo” lipid fermentation and “ex novo” lipid fermentation). To date, most of the research on lipid fermentation has focused mainly on only one fermentation pathway and little work was carried out on both “de novo” and “ex novo” lipid fermentation simultaneously; thus, the advantages of both lipid fermentation cannot be fulfilled comprehensively. Results In this study, corncob acid hydrolysate with soybean oil was used as a mix-medium for combined “de novo” and “ex novo” lipid fermentation by oleaginous yeast Trichosporon dermatis. Both hydrophilic and hydrophobic substrates (sugars and soybean oil) in the medium can be utilized simultaneously and efficiently by T. dermatis. Different fermentation modes were compared and the batch mode was the most suitable for the combined fermentation. The influence of soybean oil concentration, inoculum size, and initial pH on the lipid fermentation was evaluated and 20 g/L soybean oil, 5% inoculum size, and initial pH 6.0 were suitable for this bioprocess. By this technology, the lipid composition of extracellular hydrophobic substrate (soybean oil) can be modified. Although adding emulsifier showed little beneficial effect on lipid production, it can modify the intracellular lipid composition of T. dermatis. Conclusions The present study proves the potential and possibility of combined “de novo” and “ex novo” lipid fermentation. This technology can use hydrophilic and hydrophobic sustainable bio-resources to generate lipid feedstock for the production of biodiesel or other lipid-based chemical compounds and to treat some special wastes such as oil-containing wastewater. more...

Background: Trichosporon species are ubiquitously spread and known to be part of the normal human flora of the skin and gastrointestinal tract. Trichosporon spp. normally cause superficial infections. However, in the past decade Trichosporon spp. are emerging as opportunistic agents of invasive fungal infections, particularly in severely immunocompromised patients. Clinical isolates are usually sensitive to triazoles, but strains resistant to multiple triazoles have been reported.Case Presentation: We report a high-level pan-azole resistant Trichosporon dermatis isolate causing an invasive cholangitis in a patient after liver re-transplantation. This infection occurred despite of fluconazole and low dose amphotericin B prophylaxis, and treatment with combined liposomal amphotericin B and voriconazole failed.Conclusion: This case and recent reports in literature show that not only bacteria are evolving towards pan-resistance, but also pathogenic yeasts. Prudent use of antifungals is important to withstand emerging antifungal resistance. [ABSTRACT FROM AUTHOR] more...

In present study, the beneficial effect of corncob acid hydrolysate environment on lipid fermentation of Trichosporon dermatis was elucidated by method of cell biology (mainly using flow cytometry and microscope) for the first time. Propidium iodide (PI) and rhodamine 123 (Rh123) staining showed that corncob acid hydrolysate environment was favorable for the cell membrane integrity and mitochondrial membrane potential of T. dermatis and thus made its lipid fermentation more efficient. Nile red (NR) staining showed that corncob acid hydrolysate environment made the lipid accumulation of T. dermatis slower, but this influence was not serious. Moreover, the cell morphology of T. dermatis elongated in the corncob acid hydrolysate, but the cell morphology changed as elliptical-like during fermentation. Overall, this work offers one simple and effective method to evaluate the influence of lignocellulosic hydrolysates environment on lipid fermentation. [ABSTRACT FROM AUTHOR] more...

In this work, corncob acid hydrolysate and its simulated medium whose sugar composition was the same as the corncob acid hydrolysate were used as fermentation substrate for lipid production by oleaginous yeastTrichosporon dermatis. On the corncob acid hydrolysate, after 7 days of fermentation, the biomass, lipid content, lipid yield, and lipid coefficient ofT. dermatiswere 17.3 g/L, 40.2%, 7.0 g/L, and 16.5%, respectively. Interestingly, during the lipid fermentation on the corncob acid hydrolysate, glucose, xylose, arabinose, and even acetic acid could be well utilized as carbon sources byT. dermatis. Surprisingly, the lipid yield (7.0 g/L) ofT. dermatison the corncob acid hydrolysate was much higher than that (3.8 g/L) on the simulated medium, in spite of the fact that the lipid coefficient (17.4%) on the simulated medium was a little higher. This phenomenon further showed that lignocellulosic acid hydrolysate was a suitable substrate for lipid fermentation byT. dermatis. This work would help the comprehensive utilization of lignocellulosic biomass for lipid production. [ABSTRACT FROM PUBLISHER] more...

Abstract: In this work, microbial conversion of wastewater from butanol fermentation to microbial oil by oleaginous yeast Trichosporon dermatis was carried out for the first time. Wastewater with high COD generated from butanol fermentation mainly contained acetic acid, butyric acid and residual sugars (xylose and arabinose). Without any pretreatment and adding nutrients (nitrogen sources and trace elements), this wastewater was utilized by oleaginous yeast T. dermatis for microbial oil production. After five days'' fermentation, the COD of this wastewater has been removed for about 68%, and the highest biomass and lipid content of T. dermatis were 7.4 g/l and 13.5% respectively. This bioconversion could both solve the environmental problem and offer low-cost lipid feedstock for biodiesel production. [Copyright &y& Elsevier] more...

Corncob was hydrolyzed with Trichoderma reesei cellulase and used as substrate for growth by the oleaginous yeast Trichosporon dermatis without detoxification or addition of a nitrogen source or trace elements. A total biomass of 24.4 g/L with a lipid content of 40.1% (corresponding to a lipid yield of 9.8 g/L), and a high lipid coefficient (lipid yield per mass of sugar, % g/g) of 16.7 could be achieved after cultivation for 7 days. Therefore, T. dermatis is a promising strain for microbial oil production from lignocellulosic biomass. [ABSTRACT FROM AUTHOR] more...

The pathogenicity of Trichosporon dermatis isolated from skin lesions of a patient has been examined in mice. Balb/c mice were treated with two intraperitoneal injections of 100 mg/kg cyclophosphamide on days 4 and 1 and one subcutaneous injection of 10 mg/kg dexamethasone on day 1 pre-inoculation, and then challenged with 0.2 ml T. dermatis inoculum (1 × 10 CFU/ml) by topical application on an abrasive wound in the dermabrasive group and by hypodermic injection in the subcutaneous group. In the intravenous group, 0.2 ml of high (1 × 10 CFU/ml) or low (1 × 10CFU/ml) inoculum was injected into the tail vein. Histopathology and inverse fungal culture were performed on the skin lesion and viscera, and renal fungal burden was also determined. Inoculated sites developed localized infections after dermabrasive and subcutaneous challenge in all mice, but the maximum area of skin lesions, and number of positive cultures from the lesions, were higher for immunocompromised mice. In the intravenous group, all immunocompetent animals survived during the four-week period, whereas 100 and 70% of immunocompromised animals died by 3 and 5 days in the high and low-inoculum groups, respectively. The incidence of disseminated infection and the renal fungal burden of immunocompromised mice were higher than those of immunocompetent mice. Our results demonstrate that subcutaneous and intravenous injection of T. dermatis can successfully establish cutaneous and systemic infection models in immunocompromised mice, with the kidney and lung being most susceptible. [ABSTRACT FROM AUTHOR] more...

• Mutation was used to improve lipid production from dual carbon sources by Trichosporon dermatis. • Mutant L7 was used to produce lipid from enzymatic hydrolysate of pretreated sugarcane bagasse. • L7 produced 34.9 g/L cell mass and 20.2 g/L lipid in shake flask fed-batch cultivation. • L7 produced 51.5 g/L cell mass and 31.3 g/L lipid in fermenter fed-batch cultivation. • L7 is highly efficient in producing lipid from glucose and xylose mixture from lignocellulose. In this study, an oleaginous yeast Trichosporon dermatis was mutated by a sequential plasma and chemical mutagenesis approach. The best mutant (L7) was investigated to produce lipid from enzymatic hydrolysates derived from pretreated sugarcane bagasse at different scales and cultivation modes. The results showed that in shake flasks, L7 produced 26.7 g/L cell mass with 14.0 g/L lipid from the hydrolysate medium containing 80 g/L glucose/xylose (mass ratio of 2:1) in batch mode, and 34.9 g/L cell mass with 20.2 g/L lipid from the medium containing a total of 120 g/L glucose/xylose (2:1) in fed-batch mode, respectively. In a 5 L fermenter, L7 produced 33.3 g/L cell mass with 18.1 g/L lipid in batch mode and 51.5 g/L cell mass with 31.3 g/L lipid in fed-batch mode, respectively. This study demonstrates that L7 is highly efficient T. dermatis strain to produce lipid using glucose and xylose mixture derived from lignocellulose. [ABSTRACT FROM AUTHOR] more...

Summary: To avoid complex procedures in measurement of lipid content of oleaginous yeast especially for that can accumulate microbial lipid in lignocellulosic hydrolysates, fluor escent method using Nile Red as fluorescent dye was applied to measure lipid content of oleaginous yeast Trichosporon dermatis. The fluorescent method was built by fitting of lipid content identified by both conventional gravimetric method and fluorescence intensity of oleaginous yeast. Within the range of lipid content measured, the fitting curves showed linear relationship with good correlation coefficient(R2=0.95), showing this method is suitable for measuring lipid content of T. dermatis in the simulated medium. To evaluate the applicability of this method for lipid fermentation using lignocellulosic acid hydrolysates as substrate, T. dermatis was cultured in corncob acid hydrolysate and rice straw acid hydrolysate and then its lipid content measured by both fluorescent method and gravimetric method were compared. The results showed that the lipid content measured by these two methods were close, therefore, this method was promising for the application in lipid fermentation in lignocellulosic acid hydrolysates. [ABSTRACT FROM AUTHOR] more...