Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.658
Filtrar
1.
Int J Mol Sci ; 23(19)2022 Oct 02.
Artículo en Inglés | MEDLINE | ID: mdl-36232994

RESUMEN

Yeasts provide attractive host/vector systems for heterologous gene expression. The currently used yeast-based expression platforms include mesophilic and thermotolerant species. A eukaryotic expression system working at low temperatures could be particularly useful for the production of thermolabile proteins and proteins that tend to form insoluble aggregates. For this purpose, an expression system based on an Antarctic psychrotolerant yeast Debaryomyces macquariensis strain D50 that is capable of growing at temperatures ranging from 0 to 30 °C has been developed. The optimal physical culture conditions for D. macquariensis D50 in a fermenter are as follows: temperature 20 °C, pH 5.5, aeration rate of 1.5 vvm, and a stirring speed of 300 rpm. Four integrative plasmid vectors equipped with an expression cassette containing the constitutive GAP promoter and CYC1 transcriptional terminator from D. macquariensis D50 were constructed and used to clone and express a gene-encoding cold-active ß-d-galactosidase of Paracoccus sp. 32d. The yield was 1150 U/L of recombinant yeast culture. Recombinant D. macquariensis D50 strains were mitotically stable under both selective and non-selective conditions. The D. macquariensis D50 host/vector system has been successfully utilized for the synthesis of heterologous thermolabile protein, and it can be an alternative to other microbial expression systems.


Asunto(s)
Paracoccus , Saccharomycetales , beta-Galactosidasa , Fermentación , Galactosidasas , Paracoccus/enzimología , Saccharomycetales/metabolismo , beta-Galactosidasa/biosíntesis
2.
Waste Manag ; 131: 403-411, 2021 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-34247138

RESUMEN

Converting wastes to valuable products is the main target for many kinds of research nowadays. Wastes represent an environmental problem and getting rid of it is not easy and causes pollution. Accordingly, this study offers production of the valuable enzyme ß-galactosidase using rice straw and orange peel as the main medium constituents. ß-galactosidase converts lactose to glucose and galactose which are simple sugars and can be fermented easily by lactose-intolerant people who represent more than 50% of the world's population. It was produced by Lactobacillus paracasei, a series isolated from fermented milk, identified using 16S ribosomal RNA gene partial sequence and had the accession number MK852178. Plackett-Burman (PB) and Central Composite (CCD) Designs optimized the production scoring 1.683(10)6 U/ml with a difference five times higher than the non-optimized medium. The addition of 0.3 or 0.6% of ß-galactosidase serves as a good fortification for manufacturing nutritional and therapeutic low-lactose yogurt with no significant differences in total protein, total solids, fat, and ash between control and all treatments. The chemical, rheological and sensory properties of the final produced yogurt were evaluated during storage periods up to 9 days at 5 °C. In conclusion, L. paracasei MK852178 ß-galactosidase is a promising additive in manufacturing low lactose yogurt for lactose-intolerant people since it reduces the lactose content and doesn't influence the chemical and sensory properties.


Asunto(s)
Citrus sinensis , Lacticaseibacillus paracasei , Oryza , beta-Galactosidasa/biosíntesis , Animales , Lactasa , Lactosa , Leche , Yogur
3.
Microb Cell Fact ; 19(1): 126, 2020 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-32513169

RESUMEN

BACKGROUND: Thermostable enzymes are commonly produced in mesophilic hosts for research and bioengineering purposes. However, these hosts do not overexpress the active forms of some biologically functional thermoenzymes. Therefore, an efficient thermophilic expression system is needed. Thermus thermophilus contains an easily manipulable genome and is therefore among the best candidate microbes for a "hot" expression system. We previously identified a strong and inducible promoter that was active in T. thermophilus under supersaturated silica conditions. Here, we report a new heterologous gene expression system based on a silica-inducible promoter in T. thermophilus. RESULTS: A Thermus sp. A4 gene encoding thermostable ß-galactosidase was cloned as a reporter gene into the expression vector pSix1, which contains a selection marker that confers thermostable resistance to hygromycin and a 600 bp DNA region containing a putative silica-inducible promoter. ß-galactosidase activity was 11-fold higher in the presence than in the absence of 10 mM silicic acid. SDS-PAGE revealed a prominent band corresponding to 73 kDa of ß-galactosidase, and this enzyme was expressed as an active and soluble protein (yield: 27 mg/L) in Thermus but as an inclusion body in Escherichia coli. Truncation of the putative silica-inducible promoter region in Thermus expression vector improved the yield of the target protein, possibly by avoiding plasmid instability due to homologous recombination. Finally, we developed an expression vector containing the pSix1 backbone and a 100 bp DNA region corresponding to the silica-inducible promoter. We used this vector to successfully express the active form of glutamate dehydrogenase from Pyrobaculum islandicum (PisGDH) without additional treatment (yield: 9.5 mg/L), whereas the expression of active PisGDH in E. coli required heat treatment. CONCLUSION: We successfully expressed the thermostable ß-galactosidase and PisGDH in T. thermophilus as active and soluble forms and achieved with our system the highest known protein expression levels in this species. These thermoenzymes were expressed in active and soluble forms. Our results validate the use of our silica-inducible expression system as a novel strategy for the intracellular overexpression of thermostable proteins.


Asunto(s)
Proteínas Bacterianas/biosíntesis , Vectores Genéticos , Regiones Promotoras Genéticas , Thermus thermophilus/genética , Clonación Molecular , Expresión Génica , Regulación Bacteriana de la Expresión Génica , Glutamato Deshidrogenasa/biosíntesis , beta-Galactosidasa/biosíntesis
4.
Metab Eng ; 57: 43-50, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31562926

RESUMEN

Acid whey, a byproduct in cheese and yogurt production, demands high costs in disposal at large quantities. Nonetheless, it contains abundant sugars and nutrients that can potentially be utilized by microorganisms. Here we report a novel platform technology that converts acid whey into value-added products using Yarrowia lipolytica. Since wild type strains do not assimilate lactose, a major carbon source in whey, a secreted ß-galactosidase was introduced. Additionally, to accelerate galactose metabolism, we overexpressed the relevant native four genes of the Leloir pathway. The engineered strain could achieve rapid total conversion of all carbon sources in acid whey, producing 6.61 g/L of fatty acids (FAs) with a yield of 0.146 g-FAs/g-substrates. Further engineering to introduce an omega-3 desaturase enabled the synthesis of α-linolenic acid from acid whey, producing 10.5 mg/gDCW within a short fermentation time. Finally, PEX10 knockout in our platform strain was shown to minimize hyphal formation in concentrated acid whey cultures, greatly improving fatty acid content. These results demonstrate the feasibility of using acid whey as a previously untapped resource for biotechnology.


Asunto(s)
Ácidos Grasos/biosíntesis , Ingeniería Metabólica , Microorganismos Modificados Genéticamente , Suero Lácteo/metabolismo , Yarrowia , Ácidos Grasos/genética , Microorganismos Modificados Genéticamente/genética , Microorganismos Modificados Genéticamente/crecimiento & desarrollo , Yarrowia/genética , Yarrowia/crecimiento & desarrollo , beta-Galactosidasa/biosíntesis , beta-Galactosidasa/genética
5.
Biomed Res Int ; 2019: 8010635, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30915359

RESUMEN

ß-Galactosidase (E.C.3.2.1.23) catalyzes the hydrolysis of lactose into glucose and galactose and the synthesis of galacto-oligosaccharides as well. The ß-galactosidases from bacteria, especially lactobacilli, and yeast have neutral pH and are much more likely to be developed as food additives. However, the challenges of cumbersome purification, product toxicity, and low yield in protein production have limited the commercialization of many excellent candidates. In this study, we identified a ß-galactosidase gene (bg42-106) in Bifidobacterium animalis ACCC05790 and expressed the gene product in Escherichia coli BL21(DE3) and Pichia pastoris GS115, respectively. The recombinant bG42-106 purified from E. coli cells was found to be optimally active at pH 6.0 and 60°C and had excellent stability over a wide pH range (5.0-8.0) and at high temperature (60°C). The specific activity of bG42-106 reached up to 2351 U/mg under optimal conditions. The galacto-oligosaccharide yield was 24.45 g/L after incubation with bG42-106 at 60°C for 2 h. When recombinant bG42-106 was expressed in Pichia pastoris GS115, it was found in the culture medium but only at a concentration of 1.73 U/ml. To increase its production, three strategies were employed, including codon optimization, disulfide formation, and fusion with a Cherry tag, with Cherry-tag fusion being most effective. The culture medium of P. pastoris that expressed Cherry-tagged bG42-106 contained 24.4 U/mL of ß-galactosidase activity, which is 14-fold greater than that produced by culture of P. pastoris harboring wild-type bG42-106.


Asunto(s)
Proteínas Bacterianas , Bifidobacterium animalis/enzimología , Bifidobacterium animalis/genética , Pichia , Proteínas Recombinantes de Fusión , beta-Galactosidasa , Proteínas Bacterianas/biosíntesis , Proteínas Bacterianas/genética , Proteínas Bacterianas/aislamiento & purificación , Clonación Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Pichia/genética , Pichia/metabolismo , Proteínas Recombinantes de Fusión/biosíntesis , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/aislamiento & purificación , beta-Galactosidasa/biosíntesis , beta-Galactosidasa/genética , beta-Galactosidasa/aislamiento & purificación
6.
Int J Mol Med ; 43(2): 717-726, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30535505

RESUMEN

Oxidative stress and neuroinflammation are important in the pathogenesis of ageing and age­related neurodegenerative diseases, including Alzheimer's disease. NADPH oxidase 2 (NOX2) is a major source of reactive oxygen species (ROS) in the brain. The nucleotide­binding oligomerisation domain (NOD)­like receptor protein 1 (NLRP1) inflammasome is responsible for the formation of pro­inflammatory molecules in neurons. Whether the NOX2­NLRP1 inflammasome signalling pathway is involved in neuronal ageing and age­related damage remains to be elucidated. Ginsenoside Rg1 (Rg1) is a steroidal saponin found in ginseng. In the present study, the primary hippocampal neurons were treated with H2O2 (200 µM) and Rg1 (1, 5 and 10 µM) for 24 h to investigate the protective effects and mechanisms of Rg1 on H2O2­induced hippocampal neuron damage, which mimics age­related damage. The results showed that H2O2 treatment significantly increased ROS production and upregulated the expression of NOX2 and the NLRP1 inflammasome, and led to neuronal senescence and damage to hippocampal neurons. Rg1 decreased ROS production, reducing the expression of NOX2 and the NLRP1 inflammasome in H2O2­treated hippocampal neurons. Furthermore, Rg1 and tempol treatment significantly decreased neuronal apoptosis and the expression of ß­galactosidase, and alleviated the neuronal senescence and damage induced by H2O2. The present study indicates that Rg1 may reduce NOX2­mediated ROS generation, inhibit NLRP1 inflammasome activation, and inhibit neuronal senescence and damage.


Asunto(s)
Fármacos del Sistema Nervioso Central/farmacología , Ginsenósidos/farmacología , Hipocampo/patología , Inflamasomas/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Neuronas/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Animales , Apoptosis/efectos de los fármacos , Caspasa 1/metabolismo , Células Cultivadas , Medicamentos Herbarios Chinos/farmacología , Peróxido de Hidrógeno , Inflamasomas/efectos de los fármacos , Interleucina-18/metabolismo , Interleucina-1beta/metabolismo , NADPH Oxidasa 2/antagonistas & inhibidores , Proteínas NLR/metabolismo , Proteínas del Tejido Nervioso/antagonistas & inhibidores , Neuronas/patología , Estrés Oxidativo/efectos de los fármacos , Ratas , Especies Reactivas de Oxígeno/metabolismo , beta-Galactosidasa/biosíntesis
7.
Metab Eng ; 52: 87-97, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30453038

RESUMEN

The biosynthesis of surfactin has attracted broad interest; however, there is a bottleneck in its low yield in wild strains and the ability to engineer Bacillus producers. Because the key metabolic mechanisms in the surfactin synthesis pathway remain unclear, genetic engineering approaches are all ending up with a single or a few gene modifications. The aim of this study is to develop a systematic engineering approach to improve the biosynthesis of surfactin. First, we restored surfactin biosynthetic activity by integrating a complete sfp gene into the nonproducing Bacillus subtilis 168 strain and obtained a surfactin titer of 0.4 g/l. Second, we reduced competition by deleting biofilm formation-related genes and nonribosomal peptide synthetases/polyketide synthase pathways (3.8% of the total genome), which increased the surfactin titer by 3.3-fold. Third, we improved cellular tolerance to surfactin by overexpressing potential self-resistance-associated proteins, which further increased the surfactin titer by 8.5-fold. Fourth, we increased the supply of precursor branched-chain fatty acids by engineering the branched-chain fatty acid biosynthesis pathway, resulting in an increase of the surfactin titer to 8.5 g/l (a 20.3-fold increase). Finally, due to the preference of the glycolytic pathway for cell growth, we diverted precursor acetyl-CoA away from cell growth to surfactin biosynthesis by enhancing the transcription of srfA. The final surfactin titer increased to 12.8 g/l, with a yield of 65.0 mmol/mol sucrose (42% of the theoretical yield) in the metabolically engineered strain. To the best of our knowledge, this is the highest titer and yield that has been reported. This study may pave the way for the commercial production of green surfactin. More broadly, our work presents another successful example of the modularization of metabolic pathways for improving titer and yield in biotechnological production.


Asunto(s)
Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Ingeniería Metabólica/métodos , Biopelículas , Endopeptidasas/genética , Ácidos Grasos/farmacología , Técnicas de Inactivación de Genes , Cetoácidos/metabolismo , Redes y Vías Metabólicas/genética , Péptidos Cíclicos/biosíntesis , Plásmidos/genética , ARN Bacteriano/genética , beta-Galactosidasa/biosíntesis
8.
Proc Natl Acad Sci U S A ; 115(33): 8346-8351, 2018 08 14.
Artículo en Inglés | MEDLINE | ID: mdl-30061400

RESUMEN

In this paper, we report an example of the engineered expression of tetrameric ß-galactosidase (ß-gal) containing varying numbers of active monomers. Specifically, by combining wild-type and single-nucleotide polymorphism plasmids at varying ratios, tetrameric ß-gal was expressed in vitro with one to four active monomers. The kinetics of individual enzyme molecules revealed four distinct populations, corresponding to the number of active monomers in the enzyme. Using single-molecule-level enzyme kinetics, we were able to measure an accurate in vitro mistranslation frequency (5.8 × 10-4 per base). In addition, we studied the kinetics of the mistranslated ß-gal at the single-molecule level.


Asunto(s)
Multimerización de Proteína , Subunidades de Proteína/fisiología , beta-Galactosidasa/fisiología , Cinética , Plásmidos , Polimorfismo de Nucleótido Simple , Biosíntesis de Proteínas , beta-Galactosidasa/biosíntesis , beta-Galactosidasa/química , beta-Galactosidasa/genética
9.
Int J Biol Macromol ; 120(Pt A): 279-287, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30036621

RESUMEN

Microbial ß-galactosidases (EC 3.1.2.23) have applications in the production of galacto-oligosaccharides, which are established prebiotic food ingredients. The ß-galactosidase from Bacillus subtilis (YesZ) was expressed as a heterologous protein in Escherichia coli, and presented an optimum activity at pH 6.5 and 40 °C. The catalytic constants Km and Vmax of the enzyme were 8.26 mM and 1.42 µmol·min-1·mg-1 against pNP-ß-d-galactopyranoside, respectively. Structural characterization revealed that YesZ is a homotrimer in solution, and homology modeling suggested that the YesZ conserves a Cys cluster zinc binding site. Flame photometry experiments confirmed the presence of bound zinc in the recombinant enzyme, and YesZ activity was inhibited by 1 mM zinc, copper and silver ions. Transgalactosylation activity of YesZ was observed with the synthetic substrate p-NP-ßGal in the presence of a d-xylose acceptor, producing a ß-d-galactopyranosyl-(1 → 4)-d-xylopyranose disaccharide. Analysis of this disaccharide by MALDI-ToF-MS/MS suggested a ß-1,4 glycosidic linkage between a non-reducing galactose residue and the xylose. The ß-galactosidase YesZ from B. subtilis is a candidate for enzymatic synthesis showing favorable thermostability (with residual activity of 50% after incubation at 30 °C for 25 h) and transgalactosylation activity.


Asunto(s)
Bacillus subtilis/enzimología , Disacáridos/síntesis química , Multimerización de Proteína , beta-Galactosidasa/química , Bacillus subtilis/genética , Disacáridos/química , Estabilidad de Enzimas , Expresión Génica , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , beta-Galactosidasa/biosíntesis , beta-Galactosidasa/genética
10.
Toxicol Sci ; 166(1): 16-24, 2018 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-30010981

RESUMEN

Cellular senescence is a tumor-suppressive mechanism which leads to near irreversible proliferative arrest. However, senescent cells can cause tissue dysfunction, in large part because they express a senescence-associated secretory phenotype (SASP) involving secretion of, amongst other factors, proinflammatory cytokines known to compromise neuronal health. Therefore, established neurotoxicants may cause neurotoxicity in vivo, in part by triggering mitotic cells in the brain to undergo senescence and adopt an inflammatory SASP which in turn could cause deleterious effects to surrounding neurons. To begin to address this hypothesis, we examined whether we could screen known neurotoxicants for their ability to cause astrocytes (a mitotic cell type especially important for maintaining neuronal health) to undergo senescence. For this purpose, we utilized inducible pluripotent stem cell-derived human astrocytes and screened an 80 compound neurotoxicant library provided by the Biomolecular Screening Branch of the NIEHS National Toxicology Program. Here we present a screening method based on induction of the senescent marker, senescent-associated beta-galactosidase (SA-ß-gal). We describe in detail an automated method for the unbiased quantitation of percentage of SA-ß-gal + astrocytes. Although our results suggest that conducting an SA-ß-gal senescence screen using human inducible pluripotent stem cell-derived astrocytes may be feasible, they also highlight challenges that likely preclude its adaptation to high-throughput. We also explore the possibility of using primary mouse astrocytes for this purpose and explain why this platform is problematic and very unlikely to yield meaningful results, even in small screens with compound replicates.


Asunto(s)
Astrocitos/efectos de los fármacos , Senescencia Celular/efectos de los fármacos , Histocitoquímica/métodos , Bibliotecas de Moléculas Pequeñas/toxicidad , beta-Galactosidasa/análisis , Animales , Astrocitos/enzimología , Biomarcadores/análisis , Biomarcadores/metabolismo , Humanos , Ratones , Cultivo Primario de Células , beta-Galactosidasa/biosíntesis
11.
Int J Biol Macromol ; 120(Pt A): 274-278, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30055277

RESUMEN

ß-Galactosidases can catalyze the hydrolysis of lactose and the synthesis of galacto-oligosaccharides (GOS) from lactose. The catalytic activity of ß-galactosidases is usually inhibited by galactose and glucose, which hampers the complete hydrolysis of lactose in food products. In this report, a ß-galactosidase (denoted as BMG) from Bacillus megaterium YZ08 without the inhibition by galactose and glucose is the first to our knowledge reported. Efficient secretory expression of BMG was successfully achieved in Bacillus subtilis WB800. With the increasing of galactose and glucose, the activity of BMG dramatically enhanced. With addition of 0.6 M galactose or 1 M glucose, the initial activity to oNPG hydrolysis was increased by 2.1-fold and 4.3-fold, respectively. Moreover, the synthetic rate of galacto-oligosaccharides was enhanced by 1.1-fold and 1.9-fold with the addition of 0.7 M galactose or glucose, respectively. The GOS (278 g/L) from 600 g/L lactose by BMG were efficiently produced within 12 h, and the substrate lactose was completely used up. These results suggest that BMG shows a potential application in the food industry.


Asunto(s)
Bacillus megaterium/genética , Bacillus subtilis , Proteínas Bacterianas , Expresión Génica , beta-Galactosidasa , Bacillus megaterium/enzimología , Bacillus subtilis/enzimología , Bacillus subtilis/genética , Proteínas Bacterianas/biosíntesis , Proteínas Bacterianas/genética , Galactosa/farmacología , Glucosa/farmacología , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genética , beta-Galactosidasa/biosíntesis , beta-Galactosidasa/genética
12.
Protein Expr Purif ; 151: 72-77, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-29894806

RESUMEN

Bacillus subtilis is widely used for the large-scale industrial production of proteins. In this study, the transcriptomes of B. subtilis 168 and B. megaterium DSM319 cells grown in stationary phase were analyzed to expand the repertoire of highly-active promoters for high-level protein expression based on the transcriptomes of these Bacillus strains. 24 genes with the highest expression levels among 2048 highly expressed gene families were chosen to examine promoter activity. The activities of four promoters with the beta-galactosidase (bgaB) gene as a reporter were stronger than those of the well-characterized strong promoter P43. The expression level of recombinant Pro-transglutaminase (pro-MTG) from Streptomyces mobaraensis achieved 87.6 U/mL and 70.7 U/mL under the control of two constitutive promoter PsodA and PydzA, respectively, compared to the promoter P43. Our study provides a basis for further studies on the Bacillus transcriptome by identifying strong promoters for industrial uses.


Asunto(s)
Bacillus megaterium/genética , Bacillus subtilis/genética , Transcriptoma/genética , Bacillus megaterium/metabolismo , Bacillus subtilis/metabolismo , Espacio Extracelular/metabolismo , Genes Reporteros , Regiones Promotoras Genéticas , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genética , Streptomyces/genética , Streptomyces/metabolismo , Transglutaminasas/biosíntesis , Transglutaminasas/genética , beta-Galactosidasa/biosíntesis , beta-Galactosidasa/genética
14.
J Basic Microbiol ; 58(6): 475-491, 2018 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29660847

RESUMEN

As of date the two temperature sensitive mutations isolated in pheST operon include pheS5 (G293 →A293 ) and pheT354. Recently, we reported that G673 of pheS defines a hot spot for intragenic suppressors of pheS5. In this investigation, in 13 independent experiments, a collection of temperature sensitive mutants were isolated by localized mutagenesis. Complementation using clones bearing pheS+ , pheT+ , and pheS+ T+ indicated that 34 mutants could harbor lesion(s) in pheS and four could be in pheT and one mutant might be a double mutant. Surprisingly, all the 34 pheS mutants harbored the very same (G293 →A293 ) transition mutation as present in the classical pheS5 mutant. Most unexpectedly, the four pheT mutants isolated harbored the same G1711 →A1711 transition, a mutation which is hitherto unreported. Since all the four pheT mutants were defined by the same G1711 →A1711 base change, we believe that getting other mutations could be hard hitting and therefore it is proposed that G1711 itself could be a "hot spot" for emergence of Ts mutations in pheT and similarly G293 itself could be a "hot spot" for Ts lesions in pheS. These results clearly imply a vital role for Glutamic acid571 (Glu571 ) of PheT and reinforce criticality of Glycine98 (Gly98 ) of PheS in the thermal stability of PheRS enzyme.


Asunto(s)
Secuencia de Bases/fisiología , Estabilidad de Enzimas/genética , Estabilidad de Enzimas/fisiología , Escherichia coli K12/enzimología , Escherichia coli K12/genética , Mutagénesis , Mapeo Cromosómico , ADN Bacteriano/análisis , Escherichia coli K12/fisiología , Genes Bacterianos/genética , Prueba de Complementación Genética , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Operón , Fenotipo , Mutación Puntual , Análisis de Secuencia , Temperatura , Transducción Genética , beta-Galactosidasa/biosíntesis
15.
Stem Cell Res Ther ; 9(1): 6, 2018 01 10.
Artículo en Inglés | MEDLINE | ID: mdl-29321040

RESUMEN

BACKGROUND: Senescent cells are undesirable in cell therapy products due to reduced therapeutic activity and risk of aberrant cellular effects, and methods for assessing senescence are needed. Early-passage mesenchymal stromal cells (MSCs) are known to be small and spindle-shaped but become enlarged upon cell aging. Indeed, cell morphology is routinely evaluated during MSC production using subjective methods. We have therefore explored the possibility of utilizing automated imaging-based analysis of cell morphology in clinical cell manufacturing. METHODS: An imaging system was adopted for analyzing changes in cell morphology of bone marrow-derived MSCs during long-term culture. Cells taken from the cultures at the desired passages were plated at low density for imaging, representing morphological changes observed in the clinical-grade cultures. The manifestations of aging and onset of senescence were monitored by population doubling numbers, expression of p16INK4a and p21Cip1/Waf1, ß-galactosidase activity, and telomeric terminal restriction fragment analysis. RESULTS: Cell area was the most statistically significant and practical parameter for describing morphological changes, correlating with biochemical senescence markers. MSCs from passages 1 (p1) and 3 (p3) were remarkably uniform in size, with cell areas between 1800 and 2500 µm2. At p5 the cells began to enlarge resulting in a 4.8-fold increase at p6-9 as compared to p1. The expression of p16INK4a and activity of ß-galactosidase had a strong correlation with the increase in cell area, whereas the expression of p21Cip1/Waf1 reached its maximum at the onset of growth arrest and subsequently decreased. Mean telomere length shortened at an apparently constant rate during culture, from 8.2 ± 0.3 kbp at p1, reaching 6.08 ± 0.6 kbp at senescence. CONCLUSIONS: Imaging analysis of cell morphology is a useful tool for evaluating aging in cell cultures throughout the lifespan of MSCs. Our findings suggest that imaging analysis can reproducibly detect aging-related changes in cell morphology in MSC cultures. These findings suggest that cell morphology is still a supreme measure of cell quality and may be utilized to develop new noninvasive imaging-based methods to screen and quantitate aging in clinical-grade cell cultures.


Asunto(s)
Senescencia Celular/fisiología , Procesamiento de Imagen Asistido por Computador/métodos , Células Madre Mesenquimatosas/citología , Control de Calidad , Proliferación Celular , Tratamiento Basado en Trasplante de Células y Tejidos , Células Cultivadas , Inhibidor p16 de la Quinasa Dependiente de Ciclina/biosíntesis , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/biosíntesis , Humanos , Homeostasis del Telómero/fisiología , beta-Galactosidasa/biosíntesis
16.
Biotechnol Bioeng ; 115(3): 557-564, 2018 03.
Artículo en Inglés | MEDLINE | ID: mdl-29131302

RESUMEN

We report a spore-based biocatalysis platform capable of producing and self-assembling active multimeric enzymes on a spore surface with a high loading density. This was achieved by co-expressing both a spore surface-anchoring scaffoldin protein containing multiple cohesin domains and a dockerin-tagged enzyme of interest in the mother cell compartment during Bacillus subtilis sporulation. Using this method, tetrameric ß-galactosidase was successfully displayed on the spore surface with a loading density of 1.4 × 104 active enzymes per spore particle. The resulting spore biocatalysts exhibited high conversion rates of transgalactosylation in water/organic emulsions. With easy manufacture, enhanced thermostability, excellent reusability, and long-term storage stability at ambient temperature, this approach holds a great potential in a wide range of biocatalysis applications especially involving organic phases.


Asunto(s)
Bacillus subtilis/enzimología , Proteínas Bacterianas , Regulación Bacteriana de la Expresión Génica , Regulación Enzimológica de la Expresión Génica , Multimerización de Proteína , Esporas Bacterianas/enzimología , beta-Galactosidasa , Proteínas Bacterianas/biosíntesis , Proteínas Bacterianas/química , Biocatálisis , beta-Galactosidasa/biosíntesis , beta-Galactosidasa/química
17.
Appl Microbiol Biotechnol ; 102(1): 17-37, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29032473

RESUMEN

Oligosaccharides are polymers with two to ten monosaccharide residues which have sweetener functions and sensory characteristics, in addition to exerting physiological effects on human health. The ones called nondigestible exhibit a prebiotic behavior being fermented by colonic microflora or stimulating the growth of beneficial bacteria, playing roles in the immune system, protecting against cancer, and preventing cardiovascular and metabolic issues. The global prebiotics market is expected to grow around 12.7% in the next 8 years, so manufacturers are developing new alternatives to obtain sustainable and efficient processes for application on a large scale. Most studied examples of biotechnological processes involve the development of new strategies for fructooligosaccharide, galactooligosaccharide, xylooligosaccharide, and mannanooligosaccharide synthesis. Among these, the use of whole cells in fermentation, synthesis of microbial enzymes (ß-fructofuranosidases, ß-galactosidases, xylanases, and ß-mannanases), and enzymatic process development (permeabilization, immobilization, gene expression) can be highlighted, especially if the production costs are reduced by the use of agro-industrial residues or by-products such as molasses, milk whey, cotton stalks, corncobs, wheat straw, poplar wood, sugarcane bagasse, and copra meal. This review comprises recent studies to demonstrate the potential for biotechnological production of oligosaccharides, and also aspects that need more investigation for future applications in a large scale.


Asunto(s)
Biotecnología/métodos , Industria de Alimentos , Oligosacáridos/genética , Oligosacáridos/metabolismo , Prebióticos , Biotecnología/economía , Colon/microbiología , Productos Lácteos , Fermentación , Glucuronatos/biosíntesis , Glucuronatos/metabolismo , Humanos , Oligosacáridos/biosíntesis , Oligosacáridos/economía , Polisacáridos/metabolismo , beta-Galactosidasa/biosíntesis , beta-Galactosidasa/metabolismo , beta-Manosidasa/biosíntesis , beta-Manosidasa/metabolismo
18.
Sci Rep ; 7(1): 12511, 2017 10 02.
Artículo en Inglés | MEDLINE | ID: mdl-28970494

RESUMEN

We describe an electrochemical measurement technique that enables bioelectronic measurements of reporter proteins in living cells as an alternative to traditional optical fluorescence. Using electronically programmable microfluidics, the measurement is in turn used to control the concentration of an inducer input that regulates production of the protein from a genetic promoter. The resulting bioelectronic and microfluidic negative-feedback loop then serves to regulate the concentration of the protein in the cell. We show measurements wherein a user-programmable set-point precisely alters the protein concentration in the cell with feedback-loop parameters affecting the dynamics of the closed-loop response in a predictable fashion. Our work does not require expensive optical fluorescence measurement techniques that are prone to toxicity in chronic settings, sophisticated time-lapse microscopy, or bulky/expensive chemo-stat instrumentation for dynamic measurement and control of biomolecules in cells. Therefore, it may be useful in creating a: cheap, portable, chronic, dynamic, and precise all-electronic alternative for measurement and control of molecules in living cells.


Asunto(s)
Técnicas Electroquímicas/métodos , Electrones , Escherichia coli/genética , Retroalimentación Fisiológica , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , beta-Galactosidasa/genética , Clorofenoles/metabolismo , Técnicas Electroquímicas/instrumentación , Escherichia coli/química , Escherichia coli/efectos de los fármacos , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Galactosa/metabolismo , Galactósidos/metabolismo , Genes Reporteros , Isopropil Tiogalactósido/farmacología , Operón Lac , Represoras Lac/genética , Represoras Lac/metabolismo , Técnicas Analíticas Microfluídicas/instrumentación , Oxidación-Reducción , Fenolsulfonftaleína/análogos & derivados , Fenolsulfonftaleína/análisis , Fenolsulfonftaleína/metabolismo , Regiones Promotoras Genéticas , beta-Galactosidasa/biosíntesis
19.
FEMS Microbiol Lett ; 364(15)2017 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-28859317

RESUMEN

Fibrobacter succinogenes rapidly colonizes the preruminant calf rumen and becomes a dominant cellulolytic bacterium in the rumen after weaning. Although F. succinogenes actively degrades cellulose in the rumen, it seems that there is no or little of its substrate, cellulose, in the rumen of preweaned calves. We thus evaluated the ability of F. succinogenes to utilize lactose, a main sugar of milk, with or without the presence of cellobiose. We grew F. succinogenes S85 on media containing 2.5% lactose combined with 0%-0.2% cellobiose or a medium with 0.2% cellobiose but without lactose. The generation times on the 0.2% cellobiose medium and the 2.5% lactose medium were 1.9 and 16.2 h, respectively. The bacterium showed rapid growth on cellobiose and diauxic growth on the lactose media containing 0.05%-0.2% cellobiose. Moreover, the production of ß-galactosidase was low in the presence of 0.1%-0.2% cellobiose. Since the ß-galactosidase contained a signal peptide and a Por secretion system C-terminal sorting domain, we speculate that the ß-galactosidase would be secreted from the bacterial cells by the Por secretion system. Our data indicate the possibility that F. succinogenes could colonize preruminant calf rumen, consuming the lactose present in cow milk.


Asunto(s)
Celobiosa/metabolismo , Fibrobacter/crecimiento & desarrollo , Fibrobacter/metabolismo , Lactosa/metabolismo , Animales , Sistemas de Secreción Bacterianos/genética , Bovinos , Medios de Cultivo/química , Fibrobacter/efectos de los fármacos , Fibrobacter/genética , Rumen/microbiología , beta-Galactosidasa/biosíntesis , beta-Galactosidasa/genética
20.
ACS Synth Biol ; 6(12): 2198-2208, 2017 12 15.
Artículo en Inglés | MEDLINE | ID: mdl-28795570

RESUMEN

Cell-free gene expression systems are emerging as an important platform for a diverse range of synthetic biology and biotechnology applications, including production of robust field-ready biosensors. Here, we combine programmed cellular autolysis with a freeze-thaw or freeze-dry cycle to create a practical, reproducible, and a labor- and cost-effective approach for rapid production of bacterial lysates for cell-free gene expression. Using this method, robust and highly active bacterial cell lysates can be produced without specialized equipment at a wide range of scales, making cell-free gene expression easily and broadly accessible. Moreover, live autolysis strain can be freeze-dried directly and subsequently lysed upon rehydration to produce active lysate. We demonstrate the utility of autolysates for synthetic biology by regulating protein production and degradation, implementing quorum sensing, and showing quantitative protection of linear DNA templates by GamS protein. To allow versatile and sensitive ß-galactosidase (LacZ) based readout we produce autolysates with no detectable background LacZ activity and use them to produce sensitive mercury(II) biosensors with LacZ-mediated colorimetric and fluorescent outputs. The autolysis approach can facilitate wider adoption of cell-free technology for cell-free gene expression as well as other synthetic biology and biotechnology applications, such as metabolic engineering, natural product biosynthesis, or proteomics.


Asunto(s)
Proteínas de Escherichia coli , Escherichia coli , Expresión Génica , Mercurio/análisis , beta-Galactosidasa , Técnicas Biosensibles/métodos , Sistema Libre de Células/química , Sistema Libre de Células/metabolismo , Escherichia coli/química , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/biosíntesis , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , beta-Galactosidasa/biosíntesis , beta-Galactosidasa/química , beta-Galactosidasa/genética
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...