Meta-analysis of the efficacy and safety of Saccharomyces boulardii versus Bifidobacterium triple live bacteria in the treatment of pediatric diarrhea / 中国药房

OBJECTIVE To compare the efficacy and safety of Saccharomyces boulardii and Bifidobacterium triple live bacteria in the treatment of pediatric diarrhea. METHODS Retrieved from PubMed， Embase， the Cochrane Library， CBM， Wanfang data， CNKI and VIP， randomized controlled trials （RCTs） about S. boulardii （S. boulardii group） versus Bifidobacterium triple liver bacteria （Bifidobacterium group） were collected. After screening the literature， extracting data and evaluating the quality， meta-analysis was performed by using RevMan 5.3 software. RESULTS A total of 9 RCTs were included， involving 898 patients. Results of meta-analysis showed there was no statistical significance in total response rate [OR＝1.69， 95%CI （0.93， 3.09）， P＝0.09]， duration of diarrhea [MD＝－1.39， 95%CI （－3.35， 0.57）， P＝0.16]， the time of abdominal pain disappearance [MD＝0.09， 95%CI（－0.87， 1.05），P＝0.86] or the incidence of adverse reactions [OR＝0.65， 95%CI （0.05， 8.03）， P＝0.74]. The number of stools in S. boulardii group was significantly less than Bifidobacterium group [MD＝－0.91， 95%CI （－1.80， －0.02）， P＝0.04]. The results of subgroup analysis showed that the duration of diarrhea in children with antibiotic-associated diarrhea in S. boulardii group was significantly shorter than Bifidobacterium group （P＜0.05）. CONCLUSIONS The efficacy and safety of S. boulardii are similar to those of Bifidobacterium in the treatment of diarrhea， but S. boulardii is better than Bifidobacterium in terms of stool number， the duration of diarrhea in children with antibiotic-associated diarrhea.

Microbiological and Chemical characterization of water kefir: An innovative source of potential probiotics for bee nutrition / Caracterización microbiológica y química del kéfir de agua: una fuente innovadora de potenciales probióticos para la nutrición de las abejas

Abstract We evaluated the microbial composition of water kefir grains and beverage overthe course of one year to determine whether the number and type of microorganisms changedover the time. Bacteria and yeast colonies with different morphologies were isolated fromwater kefir and their antimicrobial activity was evaluated against Paenibacillus larvae andAscosphaera apis. A chemical characterization of kefir was also carried out. Our results con-firmed that bacteria and yeasts were more numerous in kefir grains compared with those in thebeverage. The counts of microorganisms declined, although an important microbial community was still present in kefir after the long storage period. Eleven strains which inhibited bee pathogens were isolated from kefir. Genotypic results demonstrated that these isolates included Lentilactobacillus hilgardii, Lentilactobacillus buchneri and Saccharomyces cerevisiae. Thus, water kefir may be an innovative source of potential probiotic strains for bee nutrition in order to control honeybee diseases.

Resumen Evaluamos la composición microbiana del kéfir de agua durante un ano para determinar si la cantidad y el tipo de microorganismos cambiaban con el tiempo. Se aislaron colonias de bacterias y de levaduras con diferentes morfologías, y su actividad antimicrobiana se evaluó frente a Paenibacillus larvaey Ascosphaeraapis. También se realizó una caracterización química del kéfir. Nuestros resultados confirmaron que las bacterias y las levaduras eran más numerosas en los gránulos de kéfir en comparación con la parte líquida. Los recuentos de microorganismos disminuyeron, aunque una cantidad igualmente importante se encontró en el kéfir después de un año. Se aislaron del kéfir once cepas que inhibieron los mencionados patógenos de abejas. Los resultados genotípicos demostraron que estos aislamientos eran Lentilactobacillus hilgardii, Lentilactobacillus buchneri y Saccharomyces cerevisiae. Por lo tanto, el kéfir de agua podría ser una fuente innovadora de potenciales cepas probióticas para contribuir a la nutrición y sanidad de las abejas.

Impact of Saccharomyces boulardii on jaundice in premature infants undergoing phototherapy

Abstract Objectives To evaluate the therapeutic effect of Saccharomyces boulardii supplementation on jaundice in premature infants undergoing phototherapy. Methods In this article, the authors reviewed 100 hospitalized jaundiced premature infants under 35 weeks of gestational age. All infants were assigned to a control group (n= 45) and a treatment group (n= 55) randomly. The infants in the treatment group received S. boulardii supplementation by undergoing phototherapy and the infants in the control group were only treated by phototherapy. The total serum bilirubin levels were detected before and at the end of phototherapy, and transcutaneous bilirubin levels were measured on the 1st, 4th, 8th and 15th day of treatment. The duration of jaundice resolution and phototherapy, stool frequency, and characteristics were compared after phototherapy. Results The duration of jaundice resolution and phototherapy were shortened. Total serum bilirubin level was lower than the control group at the end of phototherapy (p < 0.05). Transcutaneous bilirubin levels decreased more significantly on the 8th and 15th day of treatment (p < 0.05), while there were no significant differences on the post-treatment 1st and 4th day (p > 0.05). In addition, bowel movements including stool frequency and Bristol Stool Form Scale ratings of stools also improved after treatment. Conclusions S. boulardii in combination with phototherapy is effective and safe in reducing bilirubin levels and duration of phototherapy, accelerating jaundice resolution in premature infants with jaundice. The procedure also provided an ideal therapeutic effect of diarrhea induced by phototherapy to promote compliance and maternal-infant bonding.

Production of limonene and its derivative in Saccharomyces cerevisiae via metabolic engineering / 生物工程学报

Limonene and its derivative perillic acid are widely used in food, cosmetics, health products, medicine and other industries as important bioactive natural products. However, inefficient plant extraction and high energy-consuming chemical synthesis hamper the industrial production of limonene and perillic acid. In this study, limonene synthase from Mentha spicata was expressed in Saccharomyces cerevisiae by peroxisome compartmentalization, and the yield of limonene was 0.038 mg/L. The genes involved in limonene synthesis, ERG10, ERG13, tHMGR, ERG12, ERG8, IDI1, MVD1, ERG20ww and tLS, were step-wise expressed via modular engineering to study their effects on limonene yield. The yield of limonene increased to 1.14 mg/L by increasing the precursor module. Using the plasmid with high copy number to express the above key genes, the yield of limonene significantly increased up to 86.74 mg/L, which was 4 337 times higher than that of the original strain. Using the limonene-producing strain as the starting strain, the production of perillic acid was successfully achieved by expressing cytochrome P450 enzyme gene from Salvia miltiorrhiza, and the yield reached 4.42 mg/L. The results may facilitate the construction of cell factory with high yield of monoterpene products by S. cerevisiae.

Construction of a 10rolGLP-1-expressing glucose-lowing Saccharomyces cerevisiae by CRISPR/Cas9 technique / 生物工程学报

To develop a novel glucose-lowering biomedicine with potential benefits in the treatment of type 2 diabetes, we used the 10rolGLP-1 gene previously constructed in our laboratory and the CRISPR/Cas9 genome editing technique to create an engineered Saccharomyces cerevisiae strain. The gRNA expression vector pYES2-gRNA, the donor vector pNK1-L-PGK-10rolGLP-1-R and the Cas9 expression vector pGADT7-Cas9 were constructed and co-transformed into S. cerevisiae INVSc1 strain, with the PGK-10rolGLP-1 expressing unit specifically knocked in through homologous recombination. Finally, an S. cerevisiae strain highly expressing the 10rolGLP-1 with glucose-lowering activity was obtained. SDS-PAGE and Western blotting results confirmed that two recombinant strains of S. cerevisiae stably expressed the 10rolGLP-1 and exhibited the desired glucose-lowering property when orally administered to mice. Hypoglycemic experiment results showed that the recombinant hypoglycemic S. cerevisiae strain offered a highly hypoglycemic effect on the diabetic mouse model, and the blood glucose decline was adagio, which can avoid the dangerous consequences caused by rapid decline in blood glucose. Moreover, the body weight and other symptoms such as polyuria also improved significantly, indicating that the orally hypoglycemic S. cerevisiae strain that we constructed may develop into an effective, safe, economic, practical and ideal functional food for type 2 diabetes mellitus treatment.

Biological Functions and Mechanism of Casein KinaseHrr25 / 中国生物化学与分子生物学报

Hrr25 is a member of the casein kinase 1 family in Saccharomyces cerevisiae and has serine / threonine protein kinase activity. It can function by phosphorylating a variety of proteins. The substrate proteins of Hrr25 include autophagy related proteins, COPII (coat protein complexes II) vesicle coat proteins Sec24 and Sec23, eukaryotic translation initiation factor 6, γ- Tubulin tub4, and extender complex protein 1, etc. In addition, Hrr25 can also interact with meiotic recombinant protein Rec8, Nucleoporin Nup53, transcription regulator Crz1, and transcription activator Haa1, etc. A variety of interacting proteins of Hrr25 enable it to play a role in autophagy, vesicular transport, microtubule assembly, meiosis, mitosis, DNA repair, ribosomal biogenesis, weak organic acid stress and other biological processes. In order to better understand the action mechanism of Hrr25 in various biological processes and the relationship between various biological processes, this paper summarizes the biological functions and action mechanism of Hrr25, and the potential significance of its research, so as to provide a theoretical basis for the further research of Hrr25.

Construction of cell factories for production of patchoulol in Saccharomyces cerevisiae / 中国中药杂志

Patchoulol is an important sesquiterpenoid in the volatile oil of Pogostemon cablin, and is also considered to be the main contributing component to the pharmacological efficacy and fragrance of P. cablin oil, which has antibacterial, antitumor, antioxidant, and other biological activities. Currently, patchoulol and its essential oil blends are in high demand worldwide, but the traditional plant extraction method has many problems such as wasting land and polluting the environment. Therefore, there is an urgent need for a new method to produce patchoulol efficiently and at low cost. To broaden the production method of patchouli and achieve the heterologous production of patchoulol in Saccharomyces cerevisiae, the patchoulol synthase(PS) gene from P. cablin was codon optimized and placed under the inducible strong promoter GAL1 to transfer into the yeast platform strain YTT-T5, thereby obtaining strain PS00 with the production of(4.0±0.3) mg·L~(-1) patchoulol. To improve the conversion rate, this study used protein fusion method to fuse SmFPS gene from Salvia miltiorrhiza with PS gene, leading to increase the yield of patchoulol to(100.9±7.4) mg·L~(-1) by 25-folds. By further optimizing the copy number of the fusion gene, the yield of patchoulol was increased by 90% to(191.1±32.7) mg·L~(-1). By optimizing the fermentation process, the strain was able to achieve a patchouli yield of 2.1 g·L~(-1) in a high-density fermentation system, which was the highest yield so far. This study provides an important basis for the green production of patchoulol.

Advances in the production of chemicals by organelle compartmentalization in Saccharomyces cerevisiae / 生物工程学报

As a generally-recognized-as-safe microorganism, Saccharomyces cerevisiae is a widely studied chassis cell for the production of high-value or bulk chemicals in the field of synthetic biology. In recent years, a large number of synthesis pathways of chemicals have been established and optimized in S. cerevisiae by various metabolic engineering strategies, and the production of some chemicals have shown the potential of commercialization. As a eukaryote, S. cerevisiae has a complete inner membrane system and complex organelle compartments, and these compartments generally have higher concentrations of the precursor substrates (such as acetyl-CoA in mitochondria), or have sufficient enzymes, cofactors and energy which are required for the synthesis of some chemicals. These features may provide a more suitable physical and chemical environment for the biosynthesis of the targeted chemicals. However, the structural features of different organelles hinder the synthesis of specific chemicals. In order to ameliorate the efficiency of product biosynthesis, researchers have carried out a number of targeted modifications to the organelles grounded on an in-depth analysis of the characteristics of different organelles and the suitability of the production of target chemicals biosynthesis pathway to the organelles. In this review, the reconstruction and optimization of the biosynthesis pathways for production of chemicals by organelle mitochondria, peroxisome, golgi apparatus, endoplasmic reticulum, lipid droplets and vacuole compartmentalization in S. cerevisiae are reviewed in-depth. Current difficulties, challenges and future perspectives are highlighted.

Construction of cell factories for production of valencene in Saccharomyces cerevisiae / 药学学报

Valencene, a kind of sesquiterpenoid with a citrus flavor, is mainly found in Valencia orange and is commonly used in cosmetics and food additives, as well as industrial synthetic nootkatone. In this study, synthetic biology was used to create a Saccharomyces cerevisiae cell factory to produce valencene. Fistly, valencene synthase gene (CnVS) from Callitropsis nootkatensis was inserted into the chromosome of the chassis strain YTT-T5. The resulting strain VAL-01 could produce 1.1 mg·L-1 valencene. Protein fusion technique was used, different valencene synthases were compared and the copy number of key genes was adjusted, yielding valencene to 436.4 mg·L-1. Then, knocking-out the transcription factor ROX1 resulted in valencene improvement by 17.4%. Moreover, the induction system of galactose was regulated, transcription factor PDR3 and INO2 were overexpressed. The engineered strain VAL-10 could produce 2 798.6 mg·L-1 valencene by high cell density fermentation method (nearly 2 500 times higher than VAL-01). This study provides a basis for green production of valencene.

Construction and preliminary application of drug carrier system based on yeast membrane vesicles / 药学学报

As an edible eukaryotic microorganism, Saccharomyces cerevisiae has the characteristics of high safety, rapid proliferation, low cost, easy transformation, etc. It has been widely used to produce vaccines, antibodies, insulin, etc. Up to now, yeast components, such as cell wall and yeast microcapsules, have been widely used in the treatment of tumors, inflammatory virus infection, post-traumatic osteoarthritis and other diseases. Among them, the components of yeast cell membrane are relatively simple and stable, which are easy to be extracted on a large scale. Therefore, yeast cell membrane material was used to construct yeast membrane vesicle nanosystem, and its biomedical application was preliminarily explored. In this study, Saccharomyces cerevisiae membrane vesicle (SMV) was prepared by co-extrusion method, and the particle size and surface potential of SMV, drug loading and release characteristics, stability, cell safety, and in vitro therapeutic effect were investigated. The results showed that the average particle size of SMV was 185.1 nm. Curcumin and silica nanoparticles were effectively encapsulated by co-incubation and ultrasonic methods, and the characteristics of cell membrane proteins were maintained. Moreover, SMV had good stability and biocompatibility. In addition, SMV could be effectively uptaken by macrophages RAW 264.7, and curcumin loaded SMV could effectively eliminate reactive oxygen species (ROS). In conclusion, the yeast plasma membrane vesicles prepared in this study could effectively deliver curcumin drugs and encapsulate nanoparticles, and could be effectively absorbed by macrophages and effectively eliminate ROS, providing new ideas and new methods for biomedical applications of yeast membrane materials.

Manipulation of IME4 expression, a global regulation strategy for metabolic engineering in Saccharomyces cerevisiae

Metabolic engineering has been widely used for production of natural medicinal molecules. However, engineering high-yield platforms is hindered in large part by limited knowledge of complex regulatory machinery of metabolic network. N6-Methyladenosine (m6A) modification of RNA plays critical roles in regulation of gene expression. Herein, we identify 1470 putatively m6A peaks within 1151 genes from the haploid Saccharomyces cerevisiae strain. Among them, the transcript levels of 94 genes falling into the pathways which are frequently optimized for chemical production, are remarkably altered upon overexpression of IME4 (the yeast m6A methyltransferase). In particular, IME4 overexpression elevates the mRNA levels of the methylated genes in the glycolysis, acetyl-CoA synthesis and shikimate/aromatic amino acid synthesis modules. Furthermore, ACS1 and ADH2, two key genes responsible for acetyl-CoA synthesis, are induced by IME4 overexpression in a transcription factor-mediated manner. Finally, we show IME4 overexpression can significantly increase the titers of isoprenoids and aromatic compounds. Manipulation of m6A therefore adds a new layer of metabolic regulatory machinery and may be broadly used in bioproduction of various medicinal molecules of terpenoid and phenol classes.

Protección del ácido clorogénico frente a lesiones inducidas por venzo(a)pireno en Saccharomyces cerevisiae / Protection of chlorogenic acid against benzo(a)pyrene-induced lesions in Saccharomyces cerevisiae / Proteção do ácido clorogênico contra lesões induzidas por benzo(a)pireno em Saccharomyces cerevisiae

El objetivo del presente estudio fue analizar el efecto del ácido clorogénico, uno de los compuestos polifenólicos con mayor concentración en la infusión de Ilex paraguariensis, sobre el daño celular y molecular inducido por el benzo(a)pireno. La infusión de Ilex paraguariensis ("mate") es bebida por la mayoría de los habitantes de Argentina, Paraguay, sur de Brasil y Uruguay. La levadura Saccharomyces cerevisiae (cepas SC7K lys2-3; SX46A y SX46Arad14() se utilizó como modelo eucariota. Las células en crecimiento exponencial se expusieron a concentraciones crecientes de benzo(a)pireno y a tratamientos combinados con una concentración de 250 ng/mL de benzo(a)pireno y ácido clorogénico a una concentración igual a la encontrada en la infusión de yerba mate. Luego de los tratamientos se determinaron fracciones de sobrevida, frecuencia mutagénica y roturas de doble cadena de ADN así como la modulación en la expresión de la proteína Rad14 a través de un análisis de Western Blot. Se observó un aumento significativo en las fracciones de sobrevida así como una disminución en la frecuencia mutagénica después de la exposición combinada con benzo(a)pireno y ácido clorogénico en comparación con los tratamientos con benzo(a)pireno como único agente. En la cepa mutante deficiente en la proteína Rad14 se observó un aumento significativo en la sensibilidad a benzo(a)pireno en comparación con la cepa SC7K lys2-3. En los tratamientos combinados de benzo(a)pireno y ácido clorogénico se observó una importante disminución de la letalidad. Con respecto a la determinación de roturas de doble cadena de ADN no se observó fraccionamiento cromosómico a la concentración de benzo(a)pireno utilizada en los experimentos. Los análisis de Western Blot mostraron un aumento en la expresión de la proteína Rad14 en las muestras tratadas con benzo(a)pireno como único agente en comparación con la muestra control. Adicionalmente se observó una disminución en la expresión de la proteína cuando en los tratamientos se utilizaron benzo(a)pireno y ácido clorogénico combinados. Los resultados indican que el ácido clorogénico disminuye significativamente la actividad mutagénica producida por el benzo(a)pireno, la cual no se encuentra relacionada con un incremento en la remoción de las lesiones inducidas por el sistema de reparación por escisión de nucleótidos.

The aim of this study was to analyze the effect of chlorogenic acid, a polyphenolic compound found at high concentrations in Ilex paraguariensis infusions, on cellular and molecular damage induced by benzo(a)pyrene. Ilex paraguariensis infusions ("mate") are consumed by most of the population in Argentina, Paraguay, southern Brazil and Uruguay. Saccharomyces cerevisiae yeast (SC7K lys2-3; SX46A and SX46Arad14( strains) were used as eukaryotic model organisms. Cells in an exponential growth phase were exposed to increasing concentrations of benzo(a)pyrene, as well as combined treatments of benzo(a)pyrene at a concentration of 250 ng/mL and chlorogenic acid at a concentration matching that which is commonly found in mate. Determinations of surviving fraction, mutagenic frequency and double strand DNA breaks induction were performed, along with the assessment of the modulation of the expression of protein Rad14 by Western Blot. A significant increase of surviving fractions and a decrease in mutagenic frequency were observed after exposure to benzo(a)pyrene plus chlorogenic acid, contrary to benzo(a)pyrene alone. A substantial increase in sensitivity to benzo(a)pyrene was observed for the Rad14 protein-deficient mutating strain when compared to the SC7K lys2-3 strain. An important decrease in lethality was observed when combined benzo(a)pyrene and chlorogenic acid treatments were applied. As for the determination of DSBs, no chromosomic fractionation was observed at the benzo(a)pyrene concentration tested in the experiments. Western Blot analysis showed an increase in the expression of protein Rad14 for samples treated with benzo(a)pyrene as a single agent when compared against the control sample. Additionally, the expression of this protein was observed to diminish when combined treatments with benzo(a)pyrene and chlorogenic acid were used. Results obtained indicate that chlorogenic acid significantly decreases the mutagenic activity of benzo(a)pyrene, which is not related to an increase in the removal of lesions induced by nucleotide excision repair system.

O objetivo deste estudo foi analisar o efeito do ácido clorogênico, um dos compostos polifenólicos com maior concentração na infusão de Ilex paraguariensis, sobre o dano celular e molecular induzido pelo benzopireno. A infusão de Ilex paraguariensis ("mate") é consumida pela maioria dos habitantes da Argentina, Paraguai, sul do Brasil e Uruguai. A levedura Saccharomyces cerevisiae (cepas SC7K lys2-3; SX46A e SX46Arad14() foi utilizada como modelo eucariótico. Células em crescimento exponencial foram expostas a concentrações crescentes de benzopireno e tratamentos combinados foram realizados com uma concentração de 250 ng/mL de benzo(a)pireno e ácido clorogênico, igual à encontrada na infusão de erva-mate. Após os tratamentos, foram determinadas as frações de sobrevivência, frequência mutagênica e quebras de fita dupla do DNA, bem como a modulação na expressão da proteína Rad14 por meio de análise de Western Blot. Um aumento significativo nas frações de sobrevivência, bem como uma diminuição na frequência mutagênica foram observados após a exposição combinada de benzo(a)pireno e ácido clorogênico em comparação com tratamentos de agente único de benzo(a)pireno. Um aumento significativo na sensibilidade ao benzo(a)pireno foi observado na cepa mutante deficiente em proteína Rad14 em comparação com a cepa SC7K lys2-3. Nos tratamentos combinados de benzo(a)pireno e ácido clorogênico, observou-se uma diminuição significativa na letalidade. Com relação à determinação das quebras de fita dupla de DNA, não foi observado fracionamento cromossômico na concentração de benzo(a)pireno utilizada nos experimentos. A partir da análise de Western Blot, observou-se um aumento na expressão da proteína Rad14 nas amostras tratadas com benzo(a)pireno como agente único em relação à amostra controle. Além disso, uma diminuição na expressão da proteína foi observada quando combinados de benzo(a)pireno e ácido clorogênico foram usados ​​nos tratamentos. Os resultados obtidos neste trabalho indicam que o ácido clorogênico diminui significativamente a atividade mutagênica produzida pelo benzo(a)pireno, a qual não está relacionada a um aumento na remoção de lesões induzidas pelo sistema de reparo por excisão de nucleotídeos.

Homeopathy on cultures of Saccharomyces cerevisiaeand impact on fermentation

Studies have shownthat homeopathy modulates the activity of both single-and multi-celled organisms;therefore, we propose a study into the action of Arnica Montanaand S. cerevisiae fungus nosode on growth "in vitro", and on the fermentation of S. cerevisiaeon brewer's wort. Methods:250 µL of medication in 30% alcohol were placed in 5 mL of Sabouraud Broth (SB) or wort, with 20 µL of fungus ata McFarland standard of 0.5 and in a dilution of 1:100. Fungal growth was evaluated via spectrophotometry at 600 nm or a cell count in a Neubauer chamber in a kinetic of 1 to 5 days' incubation at 25ºC. The production of alcohol by the fungus was evaluated using the BRIX index in the samekinetic. 1x107fungi/mL were previously incubated with medication for 5 days and, afterwards, placed in 20 mL of fresh wort, incubated at 25ºC for 7 days and evaluated for growth and sugar consumption. Resultsand Discussion: The SB results revealed that after 2days incubation with Arnica30CH, an increase in fungal growth was observed (p<0.0001), whilewith nosode 6 and 30CH there was a reduction in growth after 2 and 5 days incubation (p<0.001). The fungi incubated with Arnica30CH exhibited increased sugar consumption after 2 and5 days incubation (p<0.05), while the nosode 30CH resulted in lower sugar consumption after 2 and 3 days incubation (p<0.05). The results for fungal growth and sugar consumption with the wort were similar to those using SB.The fungalcultures previously incubated with homeopathic medication and subsequent incubation with fresh wortindicated a loss of distinction, bothin terms of fungal growth and sugar consumption. This piece of data may suggest action by the homeopathic medication only when in contact with the cells. Conclusion: The treatment of the S. cerevisiae fungus using Arnica and the S. cerevisiae nosode produced a significant modulation in fungal growth and sugar consumption.

Metabolic engineering of yeasts for green and sustainable production of bioactive ginsenosides F2 and 3β,20S-Di-O-Glc-DM

Both natural ginsenoside F2 and unnatural ginsenoside 3β,20S-Di-O-Glc-DM were reported to exhibit anti-tumor activity. Traditional approaches for producing them rely on direct extraction from Panax ginseng, enzymatic catalysis or chemical synthesis, all of which result in low yield and high cost. Metabolic engineering of microbes has been recognized as a green and sustainable biotechnology to produce natural and unnatural products. Hence we engineered the complete biosynthetic pathways of F2 and 3β,20S-Di-O-Glc-DM in Saccharomyces cerevisiae via the CRISPR/Cas9 system. The titers of F2 and 3β,20S-Di-O-Glc-DM were increased from 1.2 to 21.0 mg/L and from 82.0 to 346.1 mg/L at shake flask level, respectively, by multistep metabolic engineering strategies. Additionally, pharmacological evaluation showed that both F2 and 3β,20S-Di-O-Glc-DM exhibited anti-pancreatic cancer activity and the activity of 3β,20S-Di-O-Glc-DM was even better. Furthermore, the titer of 3β,20S-Di-O-Glc-DM reached 2.6 g/L by fed-batch fermentation in a 3 L bioreactor. To our knowledge, this is the first report on demonstrating the anti-pancreatic cancer activity of F2 and 3β,20S-Di-O-Glc-DM, and achieving their de novo biosynthesis by the engineered yeasts. Our work presents an alternative approach to produce F2 and 3β,20S-Di-O-Glc-DM from renewable biomass, which lays a foundation for drug research and development.

Dynamic control of ERG20 expression to improve production of monoterpenes by engineering Saccharomyces cerevisiae / 中国中药杂志

Monoterpenes are widely used in cosmetics, food, medicine, agriculture and other fields. With the development of synthetic biology, it is considered as a potential way to create microbial cell factories to produce monoterpenes. Engineering Saccharomyces cerevisiae to produce monoterpenes has been a research hotspot in synthetic biology. In S. cerevisiae, the production of geranyl pyrophosphate(GPP) and farnesyl pyrophosphate(FPP) is catalyzed by a bifunctional enzyme farnesyl pyrophosphate synthetase(encoded by ERG20 gene) which is inclined to synthesize FPP essential for yeast growth. Therefore, reasonable control of FPP synthesis is the basis for efficient monoterpene synthesis in yeast cell factories. In order to achieve dynamic control from GPP to FPP biosynthesis in S. cerevisiae, we obtained a novel chassis strain HP001-pERG1-ERG20 by replacing the ERG20 promoter of the chassis strain HP001 with the promoter of cyclosqualene cyclase(ERG1) gene. Further, we reconstructed the metabolic pathway by using GPP and neryl diphosphate(NPP), cis-GPP as substrates in HP001-pERG1-ERG20. The yield of GPP-derived linalool increased by 42.5% to 7.6 mg·L~(-1), and that of NPP-derived nerol increased by 1 436.4% to 8.3 mg·L~(-1). This study provides a basis for the production of monoterpenes by microbial fermentation.

Construction of cell factories for high production of ginsenoside Rh_2 in Saccharomyces cerevisiae / 中国中药杂志

Ginsenoside Rh_2 is a rare active ingredient in precious Chinese medicinal materials such as Ginseng Radix et Rhizoma, Notoginseng Radix et Rhizoma, and Panacis Quinquefolii Radix. It has important pharmacological activities such as anti-cancer and improving human immunity. However, due to the extremely low content of ginsenoside Rh_2 in the source plants, the traditional way of obtaining it has limitations. This study intended to apply synthetic biological technology to develop a cell factory of Saccharomyces cerevisiae to produce Rh_2 by low-cost fermentation. First, we used the high protopanaxadiol(PPD)-yielding strain LPTA as the chassis strain, and inserted the Panax notoginseng enzyme gene Pn1-31, together with yeast UDP-glucose supply module genes[phosphoglucose mutase 1(PGM1), α-phosphoglucose mutase(PGM2), and uridine diphosphate glucose pyrophosphorylase(UGP1)], into the EGH1 locus of yeast chromosome. The engineered strain LPTA-RH2 produced 17.10 mg·g~(-1) ginsenoside Rh_2. This strain had low yield of Rh_2 while accumulated much precursor PPD, which severely restricted the application of this strain. In order to further improve the production of ginsenoside Rh_2, we strengthened the UDP glucose supply module and ginsenoside Rh_2 synthesis module by engineered strain LPTA-RH2-T. The shaking flask yield of ginsenoside Rh_2 was increased to 36.26 mg·g~(-1), which accounted for 3.63% of the dry weight of yeast cells. Compared with those of the original strain LPTA-RH2, the final production and the conversion efficiency of Rh_2 increased by 112.11% and 65.14%, respectively. This study provides an important basis for further obtaining the industrial-grade cell factory for the production of ginsenoside Rh_2.

N-terminal truncation of prenyltransferase enhances the biosynthesis of prenylnaringenin / 生物工程学报

8-prenylnaringenin (8-PN) is a potent estrogen with high medicinal values. It also serves as an important precursor for many prenylated flavonoids. Microbial synthesis of 8-PN is mainly hindered by the low catalytic activity of prenyltransferases (PTS) and insufficient supply of precursors. In this work, a SfN8DT-1 from Sophora flavescens was used to improve the efficiency of (2S)-naringenin prenylation. The predicted structure of SfN8DT-1 showed that its main body is comprised of 9 α-helices and 8 loops, along with a long side chain formed by nearly 120 amino acids. SfN8DT-1 mutants with different side-chain truncated were tested in Saccharomyces cerevisiae. A mutant expressing the truncated enzyme at K62 site, designated as SfND8T-1-t62, produced the highest 8-PN titer. Molecular docking of SfN8DT-1-t62 with (2S)-naringenin and dimethylallyl diphosphate (DMAPP) showed that K185 was a potentially crucial residue. Alanine scanning within a range of 0.5 nm around these two substrates showed that the mutant K185A may decrease its affinity to substrates, which also indicated K185 was a potentially critical residue. Besides, the mutant K185W enhanced the affinity to ligands implied by the simulated saturation mutation, while the saturated mutation of K185 showed a great decrease in 8-PN production, indicating K185 is vital for the activity of SfN8DT-1. Subsequently, overexpressing the key genes of Mevalonate (MVA) pathway further improved the titer of 8-PN to 31.31 mg/L, which indicated that DMAPP supply is also a limiting factor for 8-PN synthesis. Finally, 44.92 mg/L of 8-PN was produced in a 5 L bioreactor after 120 h, which is the highest 8-PN titer reported to date.

URA3 affects artemisinic acid production by an engineered Saccharomyces cerevisiae in pilot-scale fermentation / 生物工程学报

CRISPR/Cas9 has been widely used in engineering Saccharomyces cerevisiae for gene insertion, replacement and deletion due to its simplicity and high efficiency. The selectable markers of CRISPR/Cas9 systems are particularly useful for genome editing and Cas9-plasmids removing in yeast. In our previous research, GAL80 gene has been deleted by the plasmid pML104-mediated CRISPR/Cas9 system in an engineered yeast, in order to eliminate the requirement of galactose supplementation for induction. The maximum artemisinic acid production by engineered S. cerevisiae 1211-2 (740 mg/L) was comparable to that of the parental strain 1211 without galactose induction. Unfortunately, S. cerevisiae 1211-2 was inefficient in the utilization of the carbon source ethanol in the subsequent 50 L pilot fermentation experiment. The artemisinic acid yield in the engineered S. cerevisiae 1211-2 was only 20%-25% compared with that of S. cerevisiae 1211. The mutation of the selection marker URA3 was supposed to affect the growth and artemisinic acid production. A ura3 mutant was successfully restored by a recombinant plasmid pML104-KanMx4-u along with a 90 bp donor DNA, resulting in S. cerevisiae 1211-3. This mutant could grow normally in a fed-batch fermentor with mixed glucose and ethanol feeding, and the final artemisinic acid yield (> 20 g/L) was comparable to that of the parental strain S. cerevisiae 1211. In this study, an engineered yeast strain producing artemisinic acid without galactose induction was obtained. More importantly, it was the first report showing that the auxotrophic marker URA3 significantly affected artemisinic acid production in a pilot-scale fermentation with ethanol feeding, which provides a reference for the production of other natural products in yeast chassis.

Engineering Saccharomyces cerevisiae for efficient production of glucaric acid / 生物工程学报

As an important dicarboxylic acids existing in nature, glucaric acid has been widely used in medical, health, and polymer materials industry, therefore it is considered as one of the "top value-added chemicals from biomass". In this study, using Saccharomyces cerevisiae as a chassis microorganism, the effects of overexpression of myo-inositol transporter Itr1, fusional expression of inositol oxygenase MIOX4 and uronate dehydrogenase Udh, and down-expression of glucose-6-phosphate dehydrogenase gene ZWF1 on the glucaric acid production were investigated. The results showed that the yield of glucaric acid was increased by 26% compared with the original strain Bga-3 under shake flask fermentation after overexpressing myo-inositol transporter Itr1. The yield of glucaric acid was increased by 40% compared with Bga-3 strain by expressing the MIOX4-Udh fusion protein. On these basis, the production of glucaric acid reached 5.5 g/L, which was 60% higher than that of Bga-3 strain. In a 5 L fermenter, the highest yield of glucaric acid was 10.85 g/L, which was increased 80% compared with that of Bga-3 strain. The application of the above metabolic engineering strategy improved the pathway efficiency and the yield of glucaric acid, which may serve as a reference for engineering S. cerevisiae to produce other chemicals.

Effect of key enzymes ubiquitination sites on the biosynthesis of naringenin / 生物工程学报

Flavonoids have a variety of biological activities and have important applications in food, medicine, cosmetics, and many other fields. Naringenin is a platform chemical for the biosynthesis of many important flavonoids. Ubiquitination plays a pivotal role in the post-translational modification of proteins and participates in the regulation of cellular activities. Ubiquitinated proteins can be degraded by the ubiquitin-protease system, which is important for maintaining the physiological activities of cells, and may also exert a significant impact on the expression of exogenous proteins. In this study, a real-time in-situ detection system for ubiquitination modification has been established in Saccharomyces cerevisiae by using a fluorescence bimolecular complementation approach. The ubiquitination level of protein was characterized by fluorescence intensity. By using the approach, the potential ubiquitination sites of proteins involved in the naringenin biosynthesis pathway have been obtained. The lysine residues of the relevant ubiquitination sites were mutated to arginine to reduce the ubiquitination level. The mutants of tyrosine ammonia-lyase (FjTAL) and chalcone synthase (SjCHS, SmCHS) showed decreased fluorescence, suggested that a decreased ubiquitination level. After fermentation verification, the S. cerevisiae expressing tyrosine ammonia-lyase FjTAL mutant FjTAL-K487R accumulated 74.2 mg/L p-coumaric acid at 72 h, which was 32.3% higher than that of the original FjTAL. The strains expressing chalcone synthase mutants showed no significant change in the titer of naringenin. The results showed that mutation of the potential ubiquitination sites of proteins involved in the naringenin biosynthesis pathway could increase the titer of p-coumaric acid and have positive effect on naringenin biosynthesis.