Non-conventional yeasts such as Yarrowia lipolytica, Pichia pastoris, Kluyveromyces marxianus, Rhodosporidium toruloides and Hansenula polymorpha have proven to be efficient cell factories in producing a variety of natural products due to their wide substrate utilization spectrum, strong tolerance to environmental stresses and other merits. With the development of synthetic biology and gene editing technology, metabolic engineering tools and strategies for non-conventional yeasts are expanding. This review introduces the physiological characteristics, tool development and current application of several representative non-conventional yeasts, and summarizes the metabolic engineering strategies commonly used in the improvement of natural products biosynthesis. We also discuss the strengths and weaknesses of non-conventional yeasts as natural products cell factories at current stage, and prospects future research and development trends.
Yeasts/genetics* ; Yarrowia/metabolism* ; Gene Editing ; Metabolic Engineering

Aims: Molecular identification of yeast has been conducted on various fermentation products. However, the identification of yeast in fermented Sumbawa mare’s milk based on the genotyping method has not been carried out. This study was aimed to determine the diversity profile of yeasts in fermented Sumbawa mare’s milk using phenetic characters and PCR-RFLP analysis technique based on the ITS region. Methodology and results: Yeast isolates were phenotypically characterized and visualized in a dendrogram using CLAD97 software. Then, the yeast DNA was extracted using heat treatment and amplified using ITS1 and ITS4 primers. The amplicons were analyzed by RFLP using HindIII and HaeIII enzymes. The phylogenetic tree was constructed using MEGA 7.0. Based on the result of grouping by phenetic analysis and PCR-RFLP, the 12 isolates were divided into four groups with different members. The results of the phenetic analysis were divided into group I (all isolates of Dompu), group II (isolate B3, B4, S3), group III (isolate B5) and group IV (isolate S1). The types of yeast that were identified molecularly and represented each group of PCR-RFLP results included in group I were Kluyveromyces marxianus D1A and K. marxianus D1B, group II: K. marxianus D7, group III: Kazachstania humilis D4, while milk from Bima and Sumbawa has one yeast species as a member of group IV, namely Pichia kudriavzevii B3. Kluyveromyces marxianus was the yeast frequently found in Sumbawa fermented mare’s milk. Conclusion, significance and impact of study Various yeast species as a consortium of the milk samples can contribute to the increasing quality of fermented Sumbawa mare’s milk.
Yeasts ; Koumiss

Biodiesel is an alternative fuel to addressing the energy shortage problem. Microbial lipids have attracted widespread attention as one of the potential feed-stocks for cost-effective and efficient biodiesel production. However, the large-scale production of microbial lipids is hampered by the complexity and the high cost of aseptic culturing approach. Metschnikowia pulcherrima is an oleaginous yeast with strong environmental adaptability. It is capable of utilizing a wide spectrum of substrates, and can be cultured under non-sterile conditions. Therefore, this yeast has great potential to replace the traditional oleaginous microorganisms, particularly in the area of recycling wastewater and solid waste for the production of biodiesel. Based on the analysis of lipid production and application conditions of M. pulcherrima, this review summarized the unique advantages of M. pulcherrima and the key factors affecting lipids production. We further discussed the feasibility of cultivating M. pulcherrima on various organic wastes under non-sterile conditions for lipids production. Moreover, we analyzed the challenges associated with M. pulcherrima's in the yield and mechanism for lipids production, and proposed perspectives for how to achieve efficient biodiesel production using this yeast.
Biofuels ; Candida ; Lipids ; Metschnikowia ; Yeasts

Methylotrophic yeasts are considered as promising cell factories for bio-manufacturing due to their several advantages such as tolerance to low pH and high temperature. In particular, their methanol utilization ability may help to establish a methanol biotransformation process, which will expand the substrate resource for bio-refinery and the product portfolio from methanol. This review summarize current progress on engineering methylotrophic yeasts for production of proteins and chemicals, and compare the strengths and weaknesses with the model yeast Saccharomyces cerevisiae. The challenges and possible solutions in metabolic engineering of methylotrophic yeasts are also discussed. With the developing efficient genetic tools and systems biology, the methylotrophic yeasts should play more important roles in future green bio-manufacturing.
Metabolic Engineering ; Methanol ; Saccharomyces cerevisiae/genetics* ; Yeasts

Over the past 30 years, Yarrowia lipolytica, Kluyveromyces, Pichia, Candida, Hansenula and other non-conventional yeasts have attracted wide attention because of their desirable phenotypes, such as rapid growth, capability of utilizing multiple substrates, and stress tolerance. A variety of synthetic biology tools are being developed for exploitation of their unique phenotypes, making them potential cell factories for the production of recombinant proteins and renewable bio-based chemicals. This review summarizes the gene editing tools and the metabolic engineering strategies recently developed for non-conventional yeasts. Moreover, the challenges and future perspectives for developing non-conventional yeasts into efficient cell factories for the production of useful products through metabolic engineering are discussed.
Gene Editing ; Metabolic Engineering ; Pichia/genetics* ; Synthetic Biology ; Yarrowia/genetics* ; Yeasts

Microbial wound infection prolonged the hospitalization and increase the cost for wound management. Silver is commonly used as antimicrobial wound dressing. However, it causes several adverse side effects. Hence, this study was aimed to evaluate the antimicrobial efficiency of Swietenia macrophylla seed extract on clinical wound pathogens. Besides, the bioactive constituents of the seed extract were also determined. S. macrophylla seeds were extracted with methanol by maceration method. The seed extract inhibited 5 test bacteria and 1 yeast on disc diffusion assay. The antibacterial activity was broad spectrum, as the extract inhibited both Gram positive and Gram negative bacteria. On kill curve analysis, the antibacterial activity of the seed extract was concentration-dependent, the increase of extract concentration resulted in more reduction of bacterial growth. The extract also caused 99.9% growth reduction of Bacillus subtilis relative to control. A total of 21 compounds were detected in gas chromatography-mass spectrometry analysis. The predominant compounds present in the extract were oleic acid (18.56%) and linoleic acid (17.72%). In conclusion, the methanolic extract of S. macrophylla seeds exhibited significant antimicrobial activity on clinical wound pathogens. Further investigations should be conducted to purify other bioactive compounds from the seeds of S. macrophylla.
Bacillus subtilis ; Bacteria ; Bandages ; Diffusion ; Gas Chromatography-Mass Spectrometry ; Gram-Negative Bacteria ; Hospitalization ; Linoleic Acid ; Meliaceae ; Methanol ; Methods ; Oleic Acid ; Silver ; Wound Infection ; Wounds and Injuries ; Yeasts

Suppressor of Variegation 3–9 Homolog 2 (SUV39H2) methylates the lysine 9 residue of histone H3 and induces heterochromatin formation, resulting in transcriptional repression or silencing of target genes. SUV39H1 and SUV39H2 have a role in embryonic development, and SUV39H1 was shown to suppress cell cycle progression associated with Rb. However, the function of human SUV39H2 has not been extensively studied. We observed that forced expression of SUV39H2 decreased cell proliferation by inducing G1 cell cycle arrest. In addition, SUV39H2 was degraded through the ubiquitin-proteasomal pathway. Using yeast two-hybrid screening to address the degradation mechanism and function of SUV39H2, we identified translationally controlled tumor protein (TCTP) as an SUV39H2-interacting molecule. Mapping of the interacting regions indicated that the N-terminal 60 amino acids (aa) of full-length SUV39H2 and the C-terminus of TCTP (120–172 aa) were critical for binding. The interaction of SUV39H2 and TCTP was further confirmed by co-immunoprecipitation and immunofluorescence staining for colocalization. Moreover, depletion of TCTP by RNAi led to up-regulation of SUV39H2 protein, while TCTP overexpression reduced SUV39H2 protein level. The half-life of SUV39H2 protein was significantly extended upon TCTP depletion. These results clearly indicate that TCTP negatively regulates the expression of SUV39H2 post-translationally. Furthermore, SUV39H2 induced apoptotic cell death in TCTP-knockdown cells. Taken together, we identified SUV39H2, as a novel target protein of TCTP and demonstrated that SUV39H2 regulates cell proliferation of lung cancer cells.
Amino Acids ; Apoptosis ; Carrier Proteins ; Cell Cycle ; Cell Death ; Cell Proliferation ; Embryonic Development ; Female ; Fluorescent Antibody Technique ; G1 Phase Cell Cycle Checkpoints ; Half-Life ; Heterochromatin ; Histones ; Humans ; Immunoprecipitation ; Lung Neoplasms ; Lysine ; Mass Screening ; Pregnancy ; Repression, Psychology ; RNA Interference ; Up-Regulation ; Yeasts

BACKGROUND: Candida auris was first isolated from the ears of Japanese and Korean patients. However, the prevalence of yeast isolates from ear cultures and their antifungal susceptibility profiles in these nations remain unclear.METHODS: We assessed yeast isolates recovered from ear cultures from a university hospital in Korea over a 4-year period from January 2014 to December 2017. Species identification was performed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and/or sequence analysis. Antifungal minimal inhibitory concentrations (MICs) were determined using the broth microdilution method of the Clinical and Laboratory Standards Institute.RESULTS: Among 81 non-duplicate isolates from ear cultures, Cadida parapsilosis was the most frequently detected yeast species (34.6%), followed by C. auris (28.4%), Candida metapsilosis (9.9%), Candida orthopsilosis (8.6%), Candida albicans (7.4%), and others (11.1%). The MICs of the isolates were 0.125 to > 64 µg/mL, ≤0.03 to 4 µg/mL, 0.25 to 1 µg/mL, 0.125 to 1 µg/mL, and ≤0.03 to 2 µg/mL for fluconazole, voriconazole, amphotericin B, caspofungin, and micafungin, respectively. Of the 81 isolates, 44.4% (36/81) showed decreased susceptibility to fluconazole (MIC ≥4 µg/mL). Of the 23 C. auris isolates, 19 (82.6%) had a fluconazole MIC of ≥32 µg/mL. None of the isolates showed resistance to amphotericin B or echinocandins. Most of these patients suffered from chronic otitis media (84%).CONCLUSION: Candida parapsilosis complex and C. auris were the yeast species identified most frequently from ear cultures and they exhibited a high rate of fluconazole non-susceptibility, particularly C. auris.
Amphotericin B ; Asian Continental Ancestry Group ; Candida ; Candida albicans ; Ear ; Echinocandins ; Fluconazole ; Humans ; Korea ; Mass Spectrometry ; Methods ; Otitis Media ; Prevalence ; Sequence Analysis ; Voriconazole ; Yeasts

Talaromyces marneffei is the only dimorphic species in its genus and causes a fatal systemic mycosis named talaromycosis. Our previous study indicated that knockdown of AcuD gene (encodes isocitrate lyase of glyoxylate bypass) of T. marneffei by RNA interference approach attenuated the virulence of T. marneffei, while the virulence of the AcuD knockout strains was not studied. In this study, T. marneffei-zebrafish infection model was successfully established through hindbrain microinjection with different amounts of T. marneffei yeast cells. After co-incubated at 28°C, the increasing T. marneffei inoculum doses result in greater larval mortality; and hyphae generation might be one virulence factor involved in T. marneffei-zebrafish infection. Moreover, the results demonstrated that the virulence of the ΔAcuD was significantly attenuated in this Zebrafish infection model.
Gene Knockout Techniques ; Hyphae ; Isocitrate Lyase ; Microinjections ; Mortality ; Rhombencephalon ; RNA Interference ; Talaromyces ; Virulence ; Yeasts ; Zebrafish

Vaccination is one of the most successful strategies to prevent diseases caused by pathogens. Although various expression systems including Escherichia coli, yeast, insect, and mammalian cells are currently used for producing many of vaccines, these conventional platforms have the limitation of post-translational modification, high cost, and expensive scalability. In this respect, the plant-based expression system has been considered as an attractive platform to produce recombinant vaccines due to fast, cost-effective and scalable production as well as safety. This review discusses the development of plant-derived vaccines and the current stage of plant-based expression system.
Antibodies ; Efficiency ; Escherichia coli ; Humans ; Insects ; Plants ; Plants, Genetically Modified ; Protein Processing, Post-Translational ; Vaccination ; Vaccines ; Vaccines, Synthetic ; Yeasts