Rhodotorula toruloides is a non-conventional red yeast that can synthesize various carotenoids and lipids. It can utilize a variety of cost-effective raw materials, tolerate and assimilate toxic inhibitors in lignocellulosic hydrolysate. At present, it is widely investigated for the production of microbial lipids, terpenes, high-value enzymes, sugar alcohols and polyketides. Given its broad industrial application prospects, researchers have carried out multi-dimensional theoretical and technological exploration, including research on genomics, transcriptomics, proteomics and genetic operation platform. Here we review the recent progress in metabolic engineering and natural product synthesis of R. toruloides, and prospect the challenges and possible solutions in the construction of R. toruloides cell factory.
Gene Editing ; Metabolic Engineering ; Rhodotorula/metabolism* ; Lipids

p-coumaric acid is an important natural phenolic compound with a variety of pharmacological activities, and also a precursor for the biosynthesis of many natural compounds. It is widely used in foods, cosmetics and medicines. Compared with the chemical synthesis and plant extraction, microbial production of p-coumaric acid has many advantages, such as energy saving and emission reduction. However, the yield of p-coumaric acid by microbial synthesis is too low to meet the requirements of large-scale industrial production. Here, to further improve p-coumaric acid production, the directed evolution of tyrosine ammonia lyase (TAL) encoded by Rhodotorula glutinis tal gene was conducted, and a high-throughput screening method was established to screen the mutant library for improve the property of TAL. A mutant with a doubled TAL catalytic activity was screened from about 10,000 colonies of the mutant library. There were three mutational amino acid sites in this TAL, namely S9Y, A11N, and E518A. It was further verified by a single point saturation mutation. When S9 was mutated to Y, I or N, or A11 was mutated to N, T or Y, the catalytic activity of TAL increased by more than 1-fold. Through combinatorial mutation of three types of mutations at the S9 and A11, the TAL catalytic activity of S9Y/A11N or S9N/A11Y mutants were significantly higher than that of other mutants. Then, the plasmid containing S9N/A11Y mutant was transformed into CP032, a tyrosine-producing E. coli strain. The engineered strain produced 394.2 mg/L p-coumaric acid, which is 2.2-fold higher than that of the control strain, via shake flask fermentation at 48 h. This work provides a new insight for the biosynthesis study of p-coumaric acid.
Ammonia-Lyases/genetics* ; Escherichia coli/genetics* ; Propionates ; Rhodotorula ; Tyrosine/genetics*

Six kinds of elicitors were prepared respectively from Neurospora crassa, Monascus purpureus, Sporobolomyces roseus, Rhodotorula rubra, Nocardia sp. N89 and Actinoplanes sp. A05. When Penicillium sp. PT95 was incubated in Czapek's agar plates containing appropriate amounts of elicitors, both its sclerotia biomass and carotenoid content accumulated in sclerotia were enhanced significantly (P < 0.01). Among tested elicitors, the elicitors from the fungi N. crassa, M. purpureus, S.-roseus and R. rubra were more effective than those from the actinomycetes Nocardia sp. N89 and Actinoplanes sp. A05; the elicitor from M. purpureus gave the highest carotenoid yield of 599 micrograms/plate, 2.76 times higher than that of control. Every one of elicitors except that from M. purpureus could increase significantly the proportion of beta-carotene in total carotenoids (P < 0.01).
Actinomycetales ; physiology ; Biomass ; Carotenoids ; biosynthesis ; Neurospora crassa ; physiology ; Nocardia ; physiology ; Penicillium ; metabolism ; Rhodotorula ; physiology

BACKGROUND: PCR-based reverse blot hybridization assay (PCR-REBA) has high sensitivity and specificity, can be performed directly on nail samples, is relatively cheaper than other molecular biologic methods, and is useful for diagnosing onychomycosis. OBJECTIVE: This study aims to compare the diagnostic efficacy of fungal culture and REBA Fungus-ID® which is a commercial PCR-REBA-based kit used for onychomycosis diagnosis. METHODS: Fifty nail samples were collected from 50 patients diagnosed with onychomycosis via direct microscopic examination using KOH preparation, and subjected to fungal culture and REBA Fungus-ID® test. RESULTS: The sensitivity of conventional fungal culture and REBA Fungus-ID® was 56% and 100%, respectively. In REBA Fungus-ID®, 43 of 50 samples were found to be infected with Trichophyton rubrum. Four of the remaining 7 samples were identified as infected with Trichophyton spp., one with Trichophyton mentagrophytes, and two revealed a panfungal DNA sequence. In fungal culture, 28 of 50 samples showed growth, of which 18 samples were identified as T. rubrum, 3 as Rhodotorula mucilaginosa, 3 as Cladosporium spp., 1 as Cyphellophora europaea, 1 as Penicillium cvjetkovicii, 1 as Lachnum soppittii, and 1 as non-dermatophytic mold. REBA Fungus-ID® and fungal culture were identical in 20 cases (40%). The non-dermatophytic fungi identified in fungal culture were considered contaminants. CONCLUSION: Nail specimens can be used directly for REBA Fungus-ID®, which has a high sensitivity for onychomycosis diagnosis. Therefore, it can be considered useful for diagnosis and identification of the causative organism in mixed infections like onychomycosis.
Base Sequence ; Cladosporium ; Coinfection ; Diagnosis* ; Fungi ; Humans ; Onychomycosis* ; Penicillium ; Polymerase Chain Reaction ; Rhodotorula ; Sensitivity and Specificity ; Trichophyton

A total of 34 species belonging to 21 genera of fungi were recorded on passion fruits of both pure and hybrid origin in Uganda, however, the pure type exhibited wider spectrum (28 species and 16 genera) than the hybrid type (21 & 15). Also, yeasts (unidentified and Rhodotorula mucilaginosa) were also encountered in high numbers. Moreover, the mean count of all mycobiota obtained from the pure type was higher than that of hybrid, despite the bigger size of the later. Members of yeasts and Cladosporium followed by Phoma, Penicillium, Fusarium and Alternaria species dominated on passion fruits of pure origin, while only C. cladosporioides, F. solani and yeasts dominated on the hybrid type. Treatment with Na-hypochlorite exhibited inhibitory effects on the total mycobiotic propagules as well as the dominant species from fruits of both types. The current results, therefore, suggest the use of Na-hypochlorite to control the post-harvest mycobiota associated with passion fruits. Regarding the mycobiota contaminating passion juice, yeasts were found to be the major contaminants with Candida parapsilosis being the most common. Moulds constituted only a minor proportion with Acremonium strictum followed by Fusarium chlamydosporum, F. moniliforme, F. acuminatum and F. solani as the most dominant species. In the heat-treated juice samples, the counts of the most commonly encountered mycobiota (both yeasts and molds) were significantly inhibited or completely eliminated. Some unidentified Bacillus species were also recovered from the juice, however, their counts in the heated samples were increased but insignificantly.
Acremonium ; Alternaria ; Bacillus ; Candida ; Cladosporium ; Fruit* ; Fungi ; Fusarium ; Heating* ; Hot Temperature* ; Penicillium ; Rhodotorula ; Uganda* ; Yeasts

In order to illustrate the effects of furfural, one of the most common inhibitory compounds in lignocellulosic hydrolysate, on oleaginous yeast Rhodotorula glutinis, we investigated the effects of different concentrations of furfural (0.1, 0.4, 0.6 and 1.5 g/L) on the biomass and lipid production of R. glutinis, as well as the effects of 1.0 g/L furfural on the utilization of glucose and xylose. Results showed that: when the furfural concentration reached 1.5 g/L, the lag phrase time was extended to 96 h, and the residual glucose was up to 17.7 g/L, with maximum biomass of only 6.6 g/L, which accounted for 47% of that in the basic medium (furfural-free), and the corresponding lipid content was reduced about 50%. Furfural showed lighter inhibitory degree on R. glutinis when xylose acted as the carbon source than glucose was the carbon source; more C18 fatty acids or unsaturated C18 fatty acids were generated in the presence of furfural.
Biomass ; Carbon ; Culture Media ; Fatty Acids ; biosynthesis ; Furaldehyde ; chemistry ; Glucose ; Industrial Microbiology ; Rhodotorula ; growth & development ; metabolism ; Xylose

Rhodotorula species are round to oval-shaped, multilateral budding, encapsulated yeasts that produce urease and do not ferment carbohydrates. Rhodotorula species form characteristic salmon-pink colored colonies owing to carotenoid pigment production. These yeasts form a part of the normal flora of moist skin and are found in the environment. Rhodotorula was traditionally considered a contaminant but is now progressively recognized as a human pathogen, especially in immunocompromised patients with central venous catheters. However, isolation of Rhodotorula species from blood has been very rarely reported in Korea. We report a case of sepsis due to Rhodotorula mucilaginosa infection in a patient who had received chemotherapy and supportive care for non-small cell lung cancer.
Carbohydrates ; Carcinoma, Non-Small-Cell Lung* ; Central Venous Catheters ; Drug Therapy ; Fungemia ; Humans ; Immunocompromised Host ; Korea ; Rhodotorula* ; Sepsis* ; Skin ; Urease ; Yeasts

Fungal peritonitis is a serious complication of continuous ambulatory peritoneal dialysis (CAPD). It has been reported with increasing frequency and has been estimated that 1- 10% of peritonitis associated with CAPD is reported to be caused by the fungus. Most cases of fungal peritonitis involve candida species, however, other oppotunistic pathogens including encapsulated yeast named Rhodotorula species have been reported. Reports of infection due to Rhodotorula species, rarely being a pathogenic organism. include septicemia, endocarditis, meningitis, ventriculitis and peritonitis. We report a case of serious fungal peritonitis caused by Rhodotorula mucilaginosa in a neonate with history of neonatal asphyxia undergoing CAPD.
Acute Kidney Injury* ; Asphyxia ; Candida ; Endocarditis ; Fungi ; Humans ; Infant, Newborn* ; Meningitis ; Peritoneal Dialysis ; Peritoneal Dialysis, Continuous Ambulatory* ; Peritonitis* ; Rhodotorula* ; Sepsis ; Yeasts

Acetic acid, as a main by-product generated in the pretreatment process of lignocellulose hydrolysis, significantly affects cell growth and lipid synthesis of oleaginous microorganisms. Therefore, we studied the tolerance of Rhodotorula glutinis to acetic acid and its lipid synthesis from substrate containing acetic acid. In the mixed sugar medium containing 6 g/L glucose and 44 g/L xylose, and supplemented with acetic acid, the cell growth was not:inhibited when the acetic acid concentration was below 10 g/L. Compared with the control, the biomass, lipid concentration and lipid content of R. glutinis increased 21.5%, 171% and 122% respectively when acetic acid concentration was 10 g/L. Furthermore, R. glutinis could accumulate lipid with acetate as the sole carbon source. Lipid concentration and lipid yield reached 3.20 g/L and 13% respectively with the initial acetic acid concentration of 25 g/L. The lipid composition was analyzed by gas chromatograph. The main composition of lipid produced with acetic acid was palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid, including 40.9% saturated fatty acids and 59.1% unsaturated fatty acids. The lipid composition was similar to that of plant oil, indicating that lipid from oleaginous yeast R. glutinis had potential as the feedstock of biodiesel production. These results demonstrated that a certain concentration of acetic acid need not to be removed in the detoxification process when using lignocelluloses hydrolysate to produce microbial lipid by R. glutinis.
Acetic Acid ; Biofuels ; Biomass ; Culture Media ; Fatty Acids ; Hydrolysis ; Industrial Microbiology ; Lignin ; chemistry ; Linoleic Acid ; Lipids ; biosynthesis ; Oleic Acid ; Rhodotorula ; metabolism

Rhodotorula species live in the environment, but can also colonize human epithelium, as well as respiratory, and gastrointestinal tracts. Reports of infection, especially in the past 2 decades, have noted increasing numbers of Rhodotorula infections, particularly in immunocompromised hosts, leading it to be considered emerging opportunistic pathogen. The major risk factors for infection were prolonged use of central venous catheters in patients with hematological and solid malignancies who are taking corticosteroids or cytotoxic drugs. Herein, we report a case of catheter-associated fungemia due to R. mucilaginosa in an immunocompetent host. The patient was admitted to the intensive care unit with mechanical ventilation for treatment of community-acquired pneumonia. After 10 days, the patient developed new-onset fever confirmed to be a result of catheter-associated blood-stream infection by R. mucilaginosa. It was successfully treated by catheter removal and intravenous amphotericin B.
Adrenal Cortex Hormones ; Amphotericin B ; Catheters ; Central Venous Catheters ; Colon ; Epithelium ; Fever ; Fungemia ; Gastrointestinal Tract ; Humans ; Immunocompromised Host ; Intensive Care Units ; Pneumonia ; Respiration, Artificial ; Rhodotorula ; Risk Factors