Yeast are comprised of diverse single-cell fungal species including budding yeast Saccharomyces cerevisiae and various nonconventional yeasts. Budding yeast is well known as an important industrial microorganism, which has been widely applied in various fields, such as biopharmaceutical and health industry, food, light industry and biofuels production. In the recent years, various yeast strains from different ecological environments have been isolated and characterized. Novel species have been continuously identified, and strains with diverse physiological characteristics such as stress resistance and production of bioactive compounds were selected, which proved abundant biodiversity of natural yeast resources. Genome mining of yeast strains, as well as multi-omics analyses (transcriptome, proteome and metabolome, etc.) can reveal diverse genetic diversity for strain engineering. The genetic resources including genes encoding various enzymes and regulatory proteins, promoters, and other elements, can be employed for development of robust strains. In addition to exploration of yeast natural diversity, phenotypes that are more suitable for industrial applications can be obtained by generation of a variety of genetic diversity through mutagenesis, laboratory adaptation, metabolic engineering, and synthetic biology design. The optimized genetic elements can be used to efficiently improve strain performance. Exploration of yeast biodiversity and genetic diversity can be employed to build efficient cell factories and produce biological enzymes, vaccines, various natural products as well as other valuable products. In this review, progress on yeast diversity is summarized, and the future prospects on efficient development and utilization of yeast biodiversity are proposed. The methods and schemes described in this review also provide a reference for exploration of diversity of other industrial microorganisms and development of efficient strains.
Biodiversity ; Biofuels ; Industrial Microbiology ; Metabolic Engineering ; Saccharomyces cerevisiae/genetics* ; Synthetic Biology

Development of "liquid sunshine" could be a key technology to deal with the issue of fossil fuel depletion. β-caryophyllene is a terpene compound with high energy density and has attracted attention for its potential application as a jet fuel. The high temperature and high light-tolerant photosynthetic cyanobacterium Synechococcus elongatus UTEX 2973 (hereafter Synechococcus 2973), whose doubling time is as short as 1.5 h, has great potential for synthesizing β-caryophyllene using sunlight and CO₂. In this study, a production of ~121.22 μg/L β-caryophyllene was achieved at 96 h via a combined strategy of pathway construction, key enzyme optimization and precursor supply enhancement. In addition, a final production of ~212.37 μg/L at 96 h was realized in a high-density cultivation. To our knowledge, this is the highest production reported for β-caryophyllene using cyanobacterial chassis and our study provide important basis for high-density fuel synthesis in cyanobacteria.
Biofuels/microbiology* ; Carbon Dioxide/metabolism* ; Light ; Photosynthesis ; Synechococcus/radiation effects*

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

Production of bioethanol using starch as raw material has become a very prominent technology. However, phytate in the raw material not only decreases ethanol production efficiency, but also increases phosphorus discharge. In this study, to decrease phytate content in an ethanol fermentationprocess, Saccharomyces cerevisiae was engineered forheterologous expression of phytase on the cell surface. The phy gene encoding phytase gene was fused with the C-terminal-half region of α-agglutinin and then inserted downstream of the secretion signal gene, to produce a yeast surface-display expression vector pMGK-AG-phy, which was then transformed into S. cerevisiae. The recombinant yeast strain, PHY, successfully displayed phytase on the surface of cells producing 6.4 U/g wet cells and its properties were further characterized. The growthrate and ethanol production of the PHY strain were faster than the parent S. cerevisiae strain in the fermentation medium by simultaneous saccharification and fermentation. Moreover, the phytate concentration decreased by 91% in dry vinasse compared to the control. In summary, we constructed recombinant S. cerevisiae strain displaying phytase on the cell surface, which could effectively reduce the content of phytate, improve the utilization value of vinasse and reduce the discharge of phosphorus. The strain reported here represents a useful novel engineering platform for developing an environment-friendly system for bioethanol production from a corn substrate.
6-Phytase ; metabolism ; Biofuels ; Ethanol ; chemistry ; Fermentation ; Industrial Microbiology ; Saccharomyces cerevisiae ; metabolism ; Starch ; chemistry ; Zea mays ; chemistry

Homoacetogens are a group of microorganisms with application potential to produce chemicals and biofuels by the bioconversion of synthesis gas. In this study, we collected waste activated sludge samples to screen homoacetogens by Hungate anaerobic technique, and studied the effect of pH on acetate and alcohol production from H2/CO2 gas. The mixed culture contained Clostridium ljungdahlii, Lysinibacillus fusiformis and Bacillus cereus. Acetate concentration achieved 31.69 mmol/L when the initial pH was 7. The mixed culture containing homoacetogen could converting H2/CO2 to acetate, which provides an efficient microbial resource for the bioconversion of synthesis gas.
Acetates ; chemistry ; Bacteria ; classification ; Biofuels ; Carbon Dioxide ; Hydrogen ; Sewage ; microbiology

In the present study, we developed a two-liquid phase fermentation system by adding 1% n-dodecane as oxygen-vector to enhance the microbial lipids productivity of Trichosporon fermentans using cassava starch hydrolysate. Results suggest that the oxygen-vector could alleviate the oxygen shortage in flask fermentation. The cell mass and lipids concentration were 101.2 g/L and 50.28 respectively in 2 L fermenter with the presence of 1% n-dodecane. Additionally, gas chromatography analysis also reveals that the microbial lipids produced by T. fermentans contained a higher percentage of saturated fatty acid in the oxygen-vector case.
Alkanes ; chemistry ; Biofuels ; Fermentation ; Industrial Microbiology ; methods ; Lipids ; biosynthesis ; Manihot ; metabolism ; Starch ; metabolism ; Trichosporon ; genetics ; metabolism

Bioenergy, as a renewable energy, is one of the best solutions to substitute part of fossil fuels. Based on the 6th World Bioenergy Symposium, this special issue includes latest reports and articles on the fields of bioethanol, biodiesel, microbial lipid, biofuel standard and aviation biofuels.
Bioelectric Energy Sources ; microbiology ; Biofuels ; microbiology ; Biotechnology ; instrumentation ; methods ; Ethanol ; isolation & purification ; metabolism

To evaluate the effectiveness of enzymatic assisted extraction (EAE) of lipid from the oleaginous yeast Rhodosporidium toruloides in the presence of beta-1,3-glucomannanase at a larger scale, we investigated the effects of enzymatic treatment and extraction conditions on lipid extraction yields at 10-L scale by using the broth of R. toruloides Y4 as the feed and ethyl acetate as the solvent. When it was treated for 0.5 h, the lipid extraction yield reached 71.1%, indicating that the enzymatic treatment process reached similar efficiency to that obtained at 10-mL scale. The inhibitory effect of emulsification was greatly reduced by repeated extraction. After extracted for three times, yields of lipid extraction, solvent recovery and total material recovery reached 92.9%, 87.0% and 94.2% respectively. As it can use the lipid production slurry with good extraction efficiency, EAE technology is promising for industrial production of microbial lipids.
Basidiomycota ; metabolism ; Biofuels ; Bioreactors ; Fermentation ; Industrial Microbiology ; Lipids ; biosynthesis ; isolation & purification ; beta-Mannosidase ; metabolism

Bacillus amyloliquefaciens B10-127 was used to produce 2,3-butanediol (2,3-BD) from residual glycerol obtained from biodiesel synthesis. Important variables for 2,3-BD fermentation, pH and dissolved oxygen, were studied. When pH was maintained constant, the yield of 2,3-BD was inhibited. The highest 2,3-BD yields were achieved by fermentation without any pH control with an optimized initial pH 6.5. Batch fermentative production of 2,3-BD by B. amyloliquefaciens was investigated using various oxygen supply methods by changing agitation speed. Based on the analysis of three kinetic parameters including specific cell growth rate (micro), specific glucose consumption rate (q(s)) and specific 2,3-BD formation rate (q(p)), a three-stage agitation speed control strategy was proposed, aimed at achieving high concentration, high yield and high productivity of 2,3-BD. Maximum concentration of 2,3-BD reached 38.1 g/L, with the productivity of 1.06 g/(L x h), which were 14.8% and 63.1% over the best results from constant agitation speeds. In a pulse fed-batch fermentation, 2,3-BD concentration and productivity were significantly improved to 71.2 g/L and 0.99 g/(L x h), respectively. To our knowledge, these results were the highest for 2,3-BD production from biodiesel-derived glycerol.
Bacillus ; classification ; metabolism ; Biofuels ; analysis ; Bioreactors ; Butylene Glycols ; metabolism ; Fermentation ; Glycerol ; metabolism ; Hydrogen-Ion Concentration ; Industrial Microbiology ; Oxygen ; analysis

Lignocellulosic biomass represents an abundant, low-cost and renewable source of potentially fermentable sugars. It is acandidate besides petroleum as feedstock for fuel and chemical production. Recent researches on utilizing lignocellulosicsas feedstock boost development of numerous-promising processes for a variety of fuels and chemicals, such as biodiesel, biohydrogen and ethanol. However, high cost in depolymerization is a primary obstacle preventing the use of lignocellulosic biomass as feedstock. Consolidated bioprocessing (CBP), refers to the bioprocess without any exogenous cellulolyotic enzymes added, converting the lignocellulosic material into biochemicals directly, which could potentially avoid the cost of the dedicated enzyme generation step by incorporating enzyme-generating, biomass-degrading and bioproduct-producing capabilities into a single organism through genetic engineering. There are two CBP strategies, native strategy and recombinant strategy. We mainly introduce the recombinant strategy, including its principle, the two responding styles, the contributions of synthetic biology and metabolic engineering and the future challenges.
Bacteria ; genetics ; metabolism ; Biofuels ; Biotechnology ; methods ; Ethanol ; metabolism ; Fungi ; genetics ; metabolism ; Hydrolases ; biosynthesis ; genetics ; Industrial Microbiology ; methods ; Lignin ; metabolism ; Metabolic Engineering ; methods ; Recombinant Proteins ; biosynthesis ; genetics