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1.
An. Facultad Med. (Univ. Repúb. Urug., En línea) ; 8(1): e203, jun. 2021. tab, graf
Article in Spanish | LILACS, BNUY, UY-BNMED | ID: biblio-1248717

ABSTRACT

El vino tinto variedad Vitis vinifera L. cv Tannat en los últimos años ha tomado relevancia por su alta concentración de polifenoles, esto le podría significar un rol protector sobre el genoma disminuyendo la formación de lesiones oxidativas. Los efectos a nivel celular de las radiaciones ionizantes en blancos como el ADN, componentes de cascadas de transducción de señales, resultan en lesiones letales, mutagénicas y recombinogénicas y en retardos en el ciclo celular. Se utilizó como modelo eucariota poblaciones de Saccharomyces cerevisiae en fase exponencial expuestas a radiación gamma (200 Gy) en presencia, o ausencia, de vino Tannat (10 % v/v) o de ácido tánico (60 µg/mL). Se estimaron las probabilidades de sobrevida y frecuencia mutagénica en distintas condiciones. Las muestras celulares expuestas a radiación ionizante presentaron una fracción de sobrevida de 0.21 ± 0.02 mientras que en las muestras irradiadas en presencia de vino Tannat o de ácido tánico la fracción de sobrevida fue de 0.33 ± 0.03 y 0.30 ± 0.03 respectivamente. Se observó en las poblaciones irradiadas un aumento significativo de la probabilidad de mutagénesis. En el caso de los tratamientos combinados se observó que la frecuencia mutagénica fue significativamente menor (gamma Tannat: 33%, gamma ácido tánico: 45% ). Estos resultados preliminares podrían indicar radioprotección moderada por parte de los compuestos estudiados, efecto que podría explicarse por las interacciones redox del ácido tánico y polifenoles contenidos en el vino con los radicales libres formados por las radiaciones ionizantes, además de la activación de vías de reparación genómica.


The red wine variety Vitis vinifera L. cv Tannat in recent years has gained relevance due to its high concentration of polyphenols, this could mean a protective role on the genome, reducing the formation of oxidative lesions. The effects at the cellular level of ionizing radiation on targets such as DNA, components of signal transduction cascades, result in lethal, mutagenic and recombinogenic lesions and delays in the cell cycle. Exponential phase populations of Saccharomyces cerevisiae exposed to gamma radiation (200 Gy) in the presence or absence of Tannat wine (10% v / v) or tannic acid (60 µg / ml) were used as a eukaryotic model. The probabilities of survival and mutagenic frequency in different conditions were estimated. Cellular samples exposed to ionizing radiation presented a survival fraction of 0.21 ± 0.02, while in samples irradiated in the presence of Tannat wine or tannic acid, the survival fraction was 0.33 ± 0.03 and 0.30 ± 0.03 respectively. A significant increase in the probability of mutagenesis was observed in irradiated populations. In the case of the combined treatments, it was observed that the mutagenic frequency was significantly lower (Tannat gamma: 33%, Tannic acid gamma: 45%). These preliminary results could indicate moderate radioprotection by the compounds studied, an effect that could be explained by the redox interactions of tannic acid and polyphenols contained in wine with the free radicals formed by ionizing radiation, in addition to the activation of genomic repair pathways.


A variedade de vinho tinto Vitis vinifera L. cv Tannat nos últimos anos tem ganhado relevância devido à sua alta concentração de polifenóis, o que pode significar um papel protetor do genoma, reduzindo a formação de lesões oxidativas. Os efeitos no nível celular da radiação ionizante em alvos como o DNA, componentes de cascatas de transdução de sinal, resultam em lesões letais, mutagênicas e recombinogênicas e atrasos no ciclo celular. Populações de fase exponencial de Saccharomyces cerevisiae expostas à radiação gama (200 Gy) na presença ou ausência de vinho Tannat (10% v / v) ou ácido tânico (60 µg / ml) foram utilizadas como modelo eucariótico. Foram estimadas as probabilidades de sobrevivência e frequência mutagênica em diferentes condições. As amostras celulares expostas à radiação ionizante apresentaram uma fração de sobrevivência de 0,21 ± 0,02, enquanto nas amostras irradiadas na presença de vinho Tannat ou ácido tânico, a fração de sobrevivência foi de 0,33 ± 0,03 e 0,30 ± 0,03, respectivamente. Um aumento significativo na probabilidade de mutagênese foi observado nas populações irradiadas. No caso dos tratamentos combinados, observou-se que a frequência mutagênica foi significativamente menor (Tannat gama: 33%, ácido tânico gama: 45%). Esses resultados preliminares podem indicar radioproteção moderada pelos compostos estudados, efeito que pode ser explicado pelas interações redox do ácido tânico e polifenóis contidos no vinho com os radicais livres formados pela radiação ionizante, além da ativação de vias de reparo genômico.


Subject(s)
Animals , Saccharomyces cerevisiae/drug effects , Saccharomyces cerevisiae/genetics , Tannins/pharmacology , Mutagenesis/drug effects , Polyphenols/pharmacology , Gamma Rays/adverse effects , Radiation-Protective Agents/pharmacology , Survival Rate , Drug Therapy, Combination , Mutation Rate
2.
Article in Chinese | WPRIM | ID: wpr-921633

ABSTRACT

Azadirachtin, as a botanical insecticide, is a highly oxidized limonoid triterpenoid existing in the seeds of Azadirachta indica. However, due to the low content in the seeds, the production of azadirachtin by seed extraction has low yield. Chemical synthesis of azadirachtin is characterized by complex process and low yield. Synthetic biology provides an alternative for the supply of azadirach-tin. In this study, two oxidosqualene cyclases AiOSC1 and MaOSC1 respectively derived from A. indica and Melia azedarach were identified in yeast. A yeast strain producing tirucalla-7,24-dien-3β-ol was constructed by integration of AiOSC1, Arabidopsis thaliana-derived squalene synthase gene(AtAQS2), and Saccharomyces cerevisiae-derived truncated 3-hydroxy-3-methyl-glutaryl coenzyme A reductase gene(PgtHMGR) into the delta site of yeast. Then, the function of MaCYP71BQ5 was successfully verified in yeast after this gene was introduced into the constructed yeast strain. This study not only laid a foundation for the biosynthesis of tirucalla-7,24-dien-3β-ol, but also provided a chassis cell for the functional identification of cytochrome oxidases(CYP450 s) in azadirachtin biosynthesis pathway.


Subject(s)
Azadirachta , Limonins , Saccharomyces cerevisiae/genetics , Triterpenes
3.
Chinese Journal of Biotechnology ; (12): 3348-3360, 2021.
Article in Chinese | WPRIM | ID: wpr-921430

ABSTRACT

Tyrosine is an important aromatic amino acid. Besides its nutritional value, tyrosine is also an important precursor for the synthesis of coumarins and flavonoids. Previously, our laboratory constructed a Saccharomyces cerevisiae strain LTH0 (ARO4K229L, ARO7G141S, Δaro10, Δzwf1, Δura3) where tyrosine feedback inhibition was released. In the present study, heterologous expression of betaxanthins synthesis genes DOD (from Mirabilis jalapa) and CYP76AD1 (from sugar beet B. vulgaris) in strain LTH0 enabled production of yellow fluorescence. The engineered strain LTH0-DOD-CYP76AD1 was subjected to UV combined with ARTP mutagenesis, followed by flow cytometry screening. Among the mutants screened, the fluorescence intensity of the mutant strain LTH2-5-DOD-CYP76AD1 at the excitation wavelength of 485 nm and emission wavelength of 505 nm was (5 941±435) AU/OD, which was 8.37 times higher than that of strain LTH0-DOD-CYP76AD1. Fourteen mutant strains were subjected to fermentation to evaluate their tyrosine producing ability. The highest extracellular tyrosine titer reached 26.8 mg/L, which was 3.96 times higher than that of strain LTH0-DOD-CYP76AD1. Heterologous expression of the tyrosine ammonia lyase FjTAL derived from Flavobacterium johnsoniae further increased the titer of coumaric acid to 119.8 mg/L, which was 1.02 times higher than that of the original strain LTH0-FjTAL.


Subject(s)
Flavobacterium , High-Throughput Screening Assays , Mirabilis , Saccharomyces cerevisiae/genetics , Tyrosine
4.
Chinese Journal of Biotechnology ; (12): 3334-3347, 2021.
Article in Chinese | WPRIM | ID: wpr-921429

ABSTRACT

Cordycepin is the key active component of medicinal fungus Cordyceps militaris, and it shows multiple functional activities such as anti-tumor and anti-virus. Cordycepin was conventionally produced by liquid fermentation of C. militaris, but the long production cycle and the low productivity constrained its development and application. In this study, two key genes for cordycepin biosynthesis (ScCNS1 and ScCNS2) were introduced into Saccharomyces cerevisiae S288C, producing 67.32 mg/L cordycepin at 240 h. Analysis of gene expression profiles indicated that ZWF1, PRS4, ADE4, ScCNS1 and ScCNS2 which encode enzymes involved in pentose phosphate pathway, purine metabolism and cordycepin biosynthesis pathway, were significantly up-regulated in the late phage of fermentation. Optimization of fermentation medium determined that 50 g/L initial glucose followed by feeding, supplemented with 5 mmol/L Cu²⁺ and 1.0 g/L adenine were the best condition. Fed-batch fermentation using the engineered yeast in a 5 L stirred fermenter produced 137.27 mg/L cordycepin at 144 h, with a productivity up to 0.95 mg/(L·h) reached, which was 240% higher than that of the control.


Subject(s)
Cordyceps , Culture Media , Deoxyadenosines , Saccharomyces cerevisiae/genetics
5.
Chinese Journal of Biotechnology ; (12): 2085-2104, 2021.
Article in Chinese | WPRIM | ID: wpr-887783

ABSTRACT

Terpenoids are a group of structurally diverse compounds with good biological activities and versatile functions such as anti-cancer and immunity-enhancing effects, and are widely used in food, healthcare and medical industries. Facilitated by the increasing understandings on the natural biosynthetic pathways of terpenoids in recent years, Saccharomyces cerevisiae has been engineered into high-yield strains for production of a variety of terpenoids, some of which have reached or become close to the level required by industrial production. In this connection, synthetic biology driven biotechnological production of terpenoids has become a promising alternative to chemical synthesis and traditional extraction approaches. This article summarizes the recent process in engineering S. cerevisiae for terpenoids biosynthesis, highlighting the effect of synthetic biology strategies by taking a couple of typical terpenoids as examples.


Subject(s)
Biosynthetic Pathways , Metabolic Engineering , Saccharomyces cerevisiae/genetics , Synthetic Biology , Terpenes
6.
Chinese Journal of Biotechnology ; (12): 2050-2076, 2021.
Article in Chinese | WPRIM | ID: wpr-887781

ABSTRACT

Plant polyphenols are phenylpropanoid derivatives including phenolic acids, stilbenes, curcumins and flavonoids. These compounds display a variety of biological and pharmacological activities such as antioxidation, vasorelaxation, anti-coagulation, anti-inflammation, anti-tumor and anti-virus, conferring a huge application potential in the sectors of drugs, foods, cosmetics, and chemicals. Microorganisms have become important hosts for heterologous synthesis of natural products due to the advantages of fast growth, easiness of culture and industrial operation. In recent years, the development of synthetic biology has boosted the microbial synthesis of plant natural products, achieving substantial progress. In this review, we summarize the synthesis of plant polyphenols in engineered Escherichia coli, Saccharomyces cerevisiae and other microorganisms equipped with the designed biosynthetic pathways of polyphenols. We also discuss the optimization strategies such as precursor engineering, dynamic regulation, and co-cultivation to improve the production of polyphenols and propose future prospects for polyphenol pathway engineering.


Subject(s)
Biosynthetic Pathways , Metabolic Engineering , Plants , Polyphenols , Saccharomyces cerevisiae/genetics
7.
Chinese Journal of Biotechnology ; (12): 1578-1602, 2021.
Article in Chinese | WPRIM | ID: wpr-878656

ABSTRACT

Since its birth in the early 1990s, metabolic engineering technology has gone 30 years rapid development. As one of the preferred chassis for metabolic engineering, S. cerevisiae cells have been engineered into microbial cell factories for the production of a variety of bulk chemicals and novel high value-added bioactive compounds. In recent years, synthetic biology, bioinformatics, machine learning and other technologies have also greatly contributed to the technological development and applications of metabolic engineering. This review summarizes the important technological development for metabolic engineering of S. cerevisiae in the past 30 years. Firstly, classical metabolic engineering tools and strategies were reviewed, followed by reviewing systems metabolic engineering and synthetic biology driven metabolic engineering approaches. The review is concluded with discussing future perspectives for metabolic engineering of S. cerevisiae in the light of state-of-the-art technological development.


Subject(s)
Computational Biology , Metabolic Engineering , Saccharomyces cerevisiae/genetics , Synthetic Biology
8.
Chinese Journal of Biotechnology ; (12): 1042-1057, 2021.
Article in Chinese | WPRIM | ID: wpr-878613

ABSTRACT

Effective utilization of xylose is a basis for economic production of biofuels or chemicals from lignocellulose biomass. Over the past 30 years, through metabolic engineering, evolutionary engineering and other strategies, the metabolic capacity of xylose of the traditional ethanol-producing microorganism Saccharomyces cerevisiae has been significantly improved. In recent years, the reported results showed that the transcriptome and metabolome profiles between xylose and glucose metabolism existed significant difference in recombinant yeast strains. Compared with glucose, the overall process of xylose metabolism exhibits Crabtree-negative characteristics, including the limited glycolytic pathway activity, which reduces the metabolic flux of pyruvate to ethanol, and the enhanced cytosolic acetyl-CoA synthesis and respiratory energy metabolism. These traits are helpful to achieve efficient synthesis of downstream products using pyruvate or acetyl-CoA as precursors. This review provides a detailed overview on the modification and optimization of xylose metabolic pathways in S. cerevisiae, the characteristics of xylose metabolism, and the construction of cell factories for production of chemicals using xylose as a carbon source. Meanwhile, the existed difficulties and challenges, and future studies on biosynthesis of bulk chemicals using xylose as an important carbon source are proposed.


Subject(s)
Biofuels , Ethanol , Fermentation , Metabolic Engineering , Saccharomyces cerevisiae/genetics , Xylose
9.
Chinese Journal of Biotechnology ; (12): 966-979, 2021.
Article in Chinese | WPRIM | ID: wpr-878607

ABSTRACT

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.


Subject(s)
Metabolic Engineering , Methanol , Saccharomyces cerevisiae/genetics , Yeasts
10.
Chinese Journal of Biotechnology ; (12): 950-965, 2021.
Article in Chinese | WPRIM | ID: wpr-878606

ABSTRACT

Saccharomyces cerevisiae is one of the most important hosts in metabolic engineering. Advanced gene editing technology has been widely used in the design and construction of S. cerevisiae cell factories. With the rapid development of gene editing technology, early gene editing technologies based on recombinase and homologous recombination have been gradually replaced by new editing systems. In this review, the principle and application of gene editing technology in S. cerevisiae are summarized. Here, we first briefly describe the classical gene editing techniques of S. cerevisiae. Then elaborate the genome editing system of MegNs, ZFNs and TALENs based on endonuclease. The latest research progress is especially introduced and discussed, including the CRISPR/Cas system, multi-copy integration of heterologous metabolic pathways, and genome-scale gene editing. Finally, we envisage the application prospects and development directions of Saccharomyces cerevisiae gene editing technology.


Subject(s)
CRISPR-Cas Systems/genetics , Endonucleases/genetics , Gene Editing , Saccharomyces cerevisiae/genetics , Technology
11.
Chinese Journal of Biotechnology ; (12): 806-815, 2021.
Article in Chinese | WPRIM | ID: wpr-878597

ABSTRACT

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.


Subject(s)
Biodiversity , Biofuels , Industrial Microbiology , Metabolic Engineering , Saccharomyces cerevisiae/genetics , Synthetic Biology
12.
Chinese Journal of Biotechnology ; (12): 2193-2205, 2020.
Article in Chinese | WPRIM | ID: wpr-878478

ABSTRACT

Endoglucanase (EG) is an important component of cellulases and play an important role in cellulose degradation. However, its application is limited due to the low yield of endoglucanase from natural microorganisms. Efficient heterologous expression of endoglucanase is an effective way to solve this problem. To obtain the engineered Saccharomyces cerevisiae for high-yield endoglucanase, endoglucanase gene was cloned from Clostridium cellulovorans, with a total length of 1 996 bp, encoding 440 amino acids, and the complete expression cassette (PαEGC) was constructed with the PGK promoter sequence from Saccharomyces cerevisiae, α-signal peptide sequence from pPIC9K plasmid and CYC1 terminator sequence from pSH65 plasmid by gene splicing by overlap extension PCR (SOE PCR), and the expression vector of endoglucanase in Saccharomyces cerevisiae was constructed by rDNA integration. The relationship between copy number and protein expression was explored. Random multicopy expression of endoglucanase was performed in Saccharomyces cerevisiae. The copy number of endoglucanase was identified by Droplet Digital PCR and explore the relationship between copy number and protein expression.The engineered Saccharomyces cerevisiae of endoglucanase with copy numbers of 1, 3, 4, 7, 9, 11, 15, 16, 19, 21, 22 and 23 were obtained by rDNA integration, respectively. The results showed that when the copy number was 15, the enzyme activity was the highest, namely 351 U/mL. The engineered strain of Saccharomyces cerevisiae for endoglucanase was successfully constructed, which can provide reference for the heterologous expression of other industrial enzymes.


Subject(s)
Cellulase/genetics , Genetic Engineering , Industrial Microbiology , Plasmids/genetics , Saccharomyces cerevisiae/genetics
13.
Electron. j. biotechnol ; 41: 88-94, sept. 2019. tab, ilus, graf
Article in English | LILACS | ID: biblio-1087247

ABSTRACT

Background: In industrial yeasts, selection and breeding for resistance to multiple stresses is a focus of current research. The objective of this study was to investigate the tolerance to multiple stresses of Saccharomyces cerevisiae obtained through an adaptive laboratory evolution strategy involving a repeated liquid nitrogen freeze­thaw process coupled with multi-stress shock selection. We also assessed the related resistance mechanisms and very high-gravity (VHG) bioethanol production of this strain. Results: Elite S. cerevisiae strain YF10-5, exhibiting improved VHG fermentation capacity and stress resistance to osmotic pressure and ethanol, was isolated following ten consecutive rounds of liquid nitrogen freeze­thaw treatment followed by plate screening under osmotic and ethanol stress. The ethanol yield of YF10-5 was 16% higher than that of the parent strain during 35% (w/v) glucose fermentation. Furthermore, there was upregulation of three genes (HSP26, HSP30, and HSP104) encoding heat-shock proteins involved in the stress response, one gene (TPS1) involved in the synthesis of trehalose, and three genes (ADH1, HXK1, and PFK1) involved in ethanol metabolism and intracellular trehalose accumulation in YF10-5 yeast cells, indicating increased stress tolerance and fermentative capacity. YF10-5 also showed excellent fermentation performance during the simultaneous saccharification and fermentation of VHG sweet potato mash, producing 13.40% (w/ v) ethanol, which corresponded to 93.95% of the theoretical ethanol yield. Conclusions: A multiple-stress-tolerant yeast clone was obtained using adaptive evolution by a freeze­thaw method coupled with stress shock selection. The selected robust yeast strain exhibits potential for bioethanol production through VHG fermentation.


Subject(s)
Saccharomyces cerevisiae/physiology , Ethanol/chemical synthesis , Saccharomyces cerevisiae/genetics , Selection, Genetic , Stress, Physiological , Trehalose , Yeasts , Breeding , Adaptation, Physiological , Hypergravity , Fermentation , Real-Time Polymerase Chain Reaction , Freezing , Heat-Shock Proteins
14.
Braz. j. microbiol ; 49(4): 808-815, Oct.-Dec. 2018. tab, graf
Article in English | LILACS | ID: biblio-974288

ABSTRACT

ABSTRACT Chicha, a type of beer made mainly with maize or cassava, is a traditional fermented beverage of the Andean region. There have only been a few studies on yeasts associated with chicha fermentation, and the species diversity occurring during the production of this beverage is not known. The objective of this study was to determine the biodiversity of yeasts in chicha, and to characterize the Saccharomyces cerevisiae populations associated with the production of chicha de jora, seven-grain chicha, chicha de yuca, and chicha de morocho in Ecuador. The molecular diversity of S. cerevisiae populations was determined by restriction polymorphism mitochondrial profiles. The beverages were characterized based on their physicochemical parameters. Twenty-six species were identified, and the most prevalent species were S. cerevisiae and Torulaspora delbrueckii. Other yeast species were isolated at low frequencies. Among 121 isolates of S. cerevisiae, 68 different mtDNA molecular profiles were identified. These results showed that chichas are fermented by a high number of different strains of S. cerevisiae. Some other species provided a minor contribution to the fermentation process. The chicha presented generally similar physicochemical parameters to those observed for other traditional fermented beverages, and can be considered as an acid fermented beverage.


Subject(s)
Saccharomyces cerevisiae/isolation & purification , Beer/microbiology , Yeasts/isolation & purification , Yeasts/metabolism , Saccharomyces cerevisiae/classification , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Beer/analysis , Yeasts/classification , Yeasts/genetics , Manihot/metabolism , Manihot/microbiology , Zea mays/metabolism , Zea mays/microbiology , Biodiversity , Ecuador , Fermentation
15.
Braz. j. microbiol ; 48(4): 791-800, Oct.-Dec. 2017. graf
Article in English | LILACS | ID: biblio-889166

ABSTRACT

ABSTRACT Lignocellulose-derived inhibitors have negative effects on the ethanol fermentation capacity of Saccharomyces cerevisiae. In this study, the effects of eight typical inhibitors, including weak acids, furans, and phenols, on glucose and xylose co-fermentation of the recombinant xylose-fermenting flocculating industrial S. cerevisiae strain NAPX37 were evaluated by batch fermentation. Inhibition on glucose fermentation, not that on xylose fermentation, correlated with delayed cell growth. The weak acids and the phenols showed additive effects. The effect of inhibitors on glucose fermentation was as follows (from strongest to weakest): vanillin > phenol > syringaldehyde > 5-HMF > furfural > levulinic acid > acetic acid > formic acid. The effect of inhibitors on xylose fermentation was as follows (from strongest to weakest): phenol > vanillin > syringaldehyde > furfural > 5-HMF > formic acid > levulinic acid > acetic acid. The NAPX37 strain showed substantial tolerance to typical inhibitors and showed good fermentation characteristics, when a medium with inhibitor cocktail or rape straw hydrolysate was used. This research provides important clues for inhibitors tolerance of recombinant industrial xylose-fermenting S. cerevisiae.


Subject(s)
Saccharomyces cerevisiae/drug effects , Xylose/metabolism , Glucose/metabolism , Phenols/metabolism , Phenols/pharmacology , Saccharomyces cerevisiae/growth & development , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Acids/metabolism , Acids/pharmacology , Industrial Microbiology , Fermentation , Furans/metabolism , Furans/pharmacology
16.
Braz. j. microbiol ; 48(3): 403-409, July-Sept. 2017. tab, graf
Article in English | LILACS | ID: biblio-889142

ABSTRACT

Abstract Very high gravity (VHG) technology was employed on industrial scale to produce ethanol from molasses (fermented) as well as by-products formation estimation. The effect of different Brix° (32, 36 and 40) air-flow rates (0.00, 0.20, 0.40, and 0.60 vvm) was studied on ethanol production. The maximum ethanol production was recorded to be 12.2% (v/v) at 40 Brix° with 0.2 vvm air-flow rate. At optimum level aeration and 40 Brix° VHG, the residual sugar level was recorded in the range of 12.5-18.5 g/L, whereas the viable cell count remained constant up to 50 h of fermentation and dry matter production increased with fermentation time. Both water and steam consumption reduced significantly under optimum conditions of Brix° and aeration rate with compromising the ethanol production. Results revealed VHG with continuous air flow is viable technique to reduce the ethanol production cost form molasses at commercial scale.


Subject(s)
Chick Embryo , Ethanol/metabolism , Industrial Microbiology/methods , Molasses/microbiology , Saccharomyces cerevisiae/metabolism , Fermentation , Hypergravity , Industrial Microbiology/instrumentation , Molasses/analysis , Molasses/economics , Saccharomyces cerevisiae/genetics
17.
Braz. j. microbiol ; 48(3): 537-543, July-Sept. 2017. graf
Article in English | LILACS | ID: biblio-889126

ABSTRACT

Abstract Metallothioneins are a superfamily of low-molecular-weight, cysteine (Cys)-rich proteins that are believed to play important roles in protection against metal toxicity and oxidative stress. The main purpose of this study was to investigate the effect of heterologous expression of a rice metallothionein isoform (OsMTI-1b) on the tolerance of Saccharomyces cerevisiae to Cd2+, H2O2 and ethanol stress. The gene encoding OsMTI-1b was cloned into p426GPD as a yeast expression vector. The new construct was transformed to competent cells of S. cerevisiae. After verification of heterologous expression of OsMTI-1b, the new strain and control were grown under stress conditions. In comparison to control strain, the transformed S. cerevisiae cells expressing OsMTI-1b showed more tolerance to Cd2+ and accumulated more Cd2+ ions when they were grown in the medium containing CdCl2. In addition, the heterologous expression of GST-OsMTI-1b conferred H2O2 and ethanol tolerance to S. cerevisiae cells. The results indicate that heterologous expression of plant MT isoforms can enhance the tolerance of S. cerevisiae to multiple stresses.


Subject(s)
Plant Proteins/genetics , Oryza/genetics , Saccharomyces cerevisiae/metabolism , Cadmium/metabolism , Gene Expression , Ethanol/metabolism , Hydrogen Peroxide/metabolism , Metallothionein/genetics , Plant Proteins/metabolism , Saccharomyces cerevisiae/genetics , Oxidative Stress , Protein Isoforms/genetics , Protein Isoforms/metabolism , Metallothionein/metabolism
18.
Braz. j. microbiol ; 48(3): 461-475, July-Sept. 2017. tab, graf
Article in English | LILACS | ID: biblio-889144

ABSTRACT

Abstract The application of high-potential thermotolerant yeasts is a key factor for successful ethanol production at high temperatures. Two hundred and thirty-four yeast isolates from Greater Mekong Subregion (GMS) countries, i.e., Thailand, The Lao People's Democratic Republic (Lao PDR) and Vietnam were obtained. Five thermotolerant yeasts, designated Saccharomyces cerevisiae KKU-VN8, KKU-VN20, and KKU-VN27, Pichia kudriavzevii KKU-TH33 and P. kudriavzevii KKU-TH43, demonstrated high temperature and ethanol tolerance levels up to 45 °C and 13% (v/v), respectively. All five strains produced higher ethanol concentrations and exhibited greater productivities and yields than the industrial strain S. cerevisiae TISTR5606 during high-temperature fermentation at 40 °C and 43 °C. S. cerevisiae KKU-VN8 demonstrated the best performance for ethanol production from glucose at 37 °C with an ethanol concentration of 72.69 g/L, a productivity of 1.59 g/L/h and a theoretical ethanol yield of 86.27%. The optimal conditions for ethanol production of S. cerevisiae KKU-VN8 from sweet sorghum juice (SSJ) at 40 °C were achieved using the Box-Behnken experimental design (BBD). The maximal ethanol concentration obtained during fermentation was 89.32 g/L, with a productivity of 2.48 g/L/h and a theoretical ethanol yield of 96.32%. Thus, the newly isolated thermotolerant S. cerevisiae KKU-VN8 exhibits a great potential for commercial-scale ethanol production in the future.


Subject(s)
Pichia/metabolism , Saccharomyces cerevisiae/metabolism , Ethanol/metabolism , Pichia/isolation & purification , Pichia/genetics , Pichia/chemistry , Asia, Southeastern , Saccharomyces cerevisiae/isolation & purification , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/chemistry , Sorghum/metabolism , Glucose/metabolism , Hot Temperature
19.
Braz. j. microbiol ; 48(2): 268-274, April.-June 2017. tab, graf
Article in English | LILACS | ID: biblio-839369

ABSTRACT

Abstract Strains of Saccharomyces cerevisiae may display characteristics that are typical of rough-type colonies, made up of cells clustered in pseudohyphal structures and comprised of daughter buds that do not separate from the mother cell post-mitosis. These strains are known to occur frequently in fermentation tanks with significant lower ethanol yield when compared to fermentations carried out by smooth strains of S. cerevisiae that are composed of dispersed cells. In an attempt to delineate genetic and phenotypic differences underlying the two phenotypes, this study analysed 10 microsatellite loci of 22 S. cerevisiae strains as well as stress resistance towards high concentrations of ethanol and glucose, low pH and cell sedimentation rates. The results obtained from the phenotypic tests by Principal-Component Analysis revealed that unlike the smooth colonies, the rough colonies of S. cerevisiae exhibit an enhanced resistance to stressful conditions resulting from the presence of excessive glucose and ethanol and high sedimentation rate. The microsatellite analysis was not successful to distinguish between the colony phenotypes as phenotypic assays. The relevant industrial strain PE-2 was observed in close genetic proximity to rough-colony although it does not display this colony morphology. A unique genetic pattern specific to a particular phenotype remains elusive.


Subject(s)
Saccharomyces cerevisiae/physiology , Saccharomyces cerevisiae/genetics , Genetic Variation , Microsatellite Repeats , Ethanol/metabolism , Phenotype , Saccharomyces cerevisiae/classification , Saccharomyces cerevisiae/metabolism , Stress, Physiological , Genotype , Glucose/metabolism , Hydrogen-Ion Concentration
20.
Braz. j. microbiol ; 47(1): 136-142, Jan.-Mar. 2016. tab, graf
Article in English | LILACS | ID: lil-775098

ABSTRACT

Abstract The kinetics of an extracellular β-D-fructofuranosidase fructohydrolase production by Saccharomyces cerevisiae in a chemically defined medium, i.e., sucrose peptone agar yeast extract at pH 6, was investigated. The wild-type was treated with a chemical mutagen, methyl methane sulfonate. Among the six mutants isolated, methyl methane sulfonate-V was found to be a better enzyme producing strain (52 ± 2.4a U/mL). The maximum production (74 ± 3.1a U/mL) was accomplished after at 48 h (68 ± 2.7a mg/mL protein). The mutants were stabilized at low levels of 5-fluoro-cytocine and the viable ones were further processed for optimization of cultural conditions and nutritional requirements. The sucrose concentration, incubation period and pH were optimized to be 30 g/L, 28 °C, and 6.5, respectively. The methyl methane sulfonate-V exhibited an improvement of over 10 folds in enzyme production when 5 g/L ammonium sulfate was used as a nitrogen source. Thin layer chromatography and high-performance liquid chromatography analysis illustrated the optimal enzyme activity supported by the higher rate of hydrolysis of sucrose into monosaccharides, particularly α-D-glucose and β-D-fructose. The values for Qp (2 ± 0.12c U/mL/h) and Yp/s (4 ± 1.24b U/g) of the mutant were considerably increased in comparison with other yeast strains (both isolates and viable mutants). The mutant could be exploited for enzyme production over a wider temperature range (26–34 °C), with significantly high enzyme activity (LSD 0.048, HS) at the optimal temperature.


Subject(s)
Mutation , Saccharomyces cerevisiae/growth & development , Saccharomyces cerevisiae/metabolism , beta-Fructofuranosidase/biosynthesis , Chromatography, High Pressure Liquid , Chromatography, Thin Layer , Culture Media/chemistry , Hydrogen-Ion Concentration , Hydrolysis , Mutagenesis , Mutagens/metabolism , Serratia , Saccharomyces cerevisiae/genetics , Sucrose/metabolism , Sulfinic Acids/metabolism , Temperature
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