Metabolic control analysis of L-tryptophan production with Escherichia coli based on data from short-term perturbation experiments

Publication date: Available online 19 October 2019Source: Journal of BiotechnologyAuthor(s): Julia Tröndle, Kristin Schoppel, Arne Bleidt, Natalia Trachtmann, Georg A. Sprenger, Dirk Weuster-BotzAbstractE. coli strain NT1259 /pF112aroFBLkan was able to produce 14.3 g L-1 L-tryptophan within 68 h in a fed-batch process from glycerol on a 15 L scale. To gain detailed insight into metabolism of this E. coli strain in the fed-batch process, a sample of L-tryptophan producing cells was withdrawn after 47 h, was separated rapidly and then resuspended in four parallel stirred-tank bioreactors with fresh media. Four different carbon sources (glucose, glycerol, succinate, pyruvate) were supplied individually with varying feeding rates within 19 min and the metabolic reactions of the cells in the four parallel reactors were analyzed by quantification of extracellular and intracellular substrate, product and metabolite concentrations. Data analysis allowed the estimation of intracellular carbon fluxes and of thermodynamic limitations concerning intracellular concentrations and reaction energies. Carbon fluxes and intracellular metabolite concentrations enabled the estimation of elasticities and flux control coefficients by applying metabolic control analysis making use of a metabolic model considering 48 enzymatic reactions and 56 metabolites. As the flux control coefficients describe connections between enzyme activities and metabolic fluxes, the...
Source: Journal of Biotechnology - Category: Biotechnology Source Type: research

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Hejátko J Abstract Determining conditions optimal for host growth, maximal protein yield, and lysis buffer composition is of critical importance for the efficient purification of soluble and well-folded recombinant proteins suitable for functional and/or structural studies. Small-scale optimization of conditions for protein production and stability saves time, labor, and costs. Here we describe a protocol for quick protein production and solubility screen using TissueLyser II system from Qiagen enabling simultaneous processing of 96 protein samples, with application to recombinant proteins encompassing two...
Source: Mol Biol Cell - Category: Molecular Biology Authors: Tags: Methods Mol Biol Source Type: research
ConclusionEthyl acetate &Water extracts have represented potent activity against Salmonella typhi, Escherichia coli, &Staphylococcus aureus bacteria as well, provided cytotoxicity against tested cancer cell lines. These results can be explored to identify individual phyto-molecules from the extracts for anticancer &antimicrobial potentials to identify new phytomedicines.
Source: European Journal of Integrative Medicine - Category: Complementary Medicine Source Type: research
koh Disease outbreaks caused by the ingestion of contaminated vegetables and fruits pose a significant problem to human health. The sources of contamination of these food products at the preharvest level of agricultural production, most importantly, agricultural soil and irrigation water, serve as potential reservoirs of some clinically significant foodborne pathogenic bacteria. These clinically important bacteria include: Klebsiella spp., Salmonella spp., Citrobacter spp., Shigella spp., Enterobacter spp., Listeria monocytogenes and pathogenic E. coli (and E. coli O157:H7) all of which have the potential to cause dise...
Source: International Journal of Environmental Research and Public Health - Category: Environmental Health Authors: Tags: Review Source Type: research
Publication date: Available online 9 November 2019Source: Journal of Microbiological MethodsAuthor(s): Sunkyung Kim, Robert Quick, Christine Stauber, Jared Oremo, Jennifer MurphyAbstractAn antimicrobial towel designed for repeated use was developed to prevent recontamination of washed hands after drying. This field trial in Kenya found that nearly all antimicrobial hand towels and untreated control towels were contaminated with E. coli after household use. The antimicrobial towel did not inactivate E. coli.
Source: Journal of Microbiological Methods - Category: Microbiology Source Type: research
Publication date: Available online 9 November 2019Source: PlasmidAuthor(s): Sarah Revitt-Mills, Carmen Lao, Marie Archambault, Dena Lyras, Julian I. Rood, Vicki AdamsAbstractMany of the disease-causing toxins of the pathogenic bacterium Clostridium perfringens are harboured on large, highly stable, conjugative plasmids. Previous work has established the requirement of a ParMRC-like partitioning system for plasmid maintenance, but little is known about other mechanisms used to ensure stable plasmid inheritance. The archetypal 47 kb Tcp plasmid, pCW3, encodes a gene, resP, whose putative product has sequence similarity to ...
Source: Plasmid - Category: Biotechnology Source Type: research
Publication date: Available online 9 November 2019Source: Protein Expression and PurificationAuthor(s): Ligia Luz Corrales-García, Leobardo Serrano-Carreón, Gerardo CorzoAbstractAt present, expressing antimicrobial peptides in bacterial models is considered a routine lab bench work. However, low expression yields of these types of proteins are usually obtained. In this work, the antimicrobial peptide human β-defensin 2 (HBD2) was obtained in low expression yields in Escherichia coli BL21(DE3). To improve the expression yields of HBD2, some variables such as cell density, temperature, and length of induct...
Source: Protein Expression and Purification - Category: Biochemistry Source Type: research
In this study, we established an artificial pathway in engineered Escherichia coli for microbial production of indole-3-ethanol from simple carbon sources. The overall pathway includes the upstream pathway from glucose to L-tryptophan and the downstream pathway from L-tryptophan to indole-3-ethanol. We have further demonstrated the biosynthesis of indole-3-ethanol acetate by overexpressing alcohol acetyltransferase ATF1 for the subsequent conversion of indole-3-ethanol to indole-3-ethanol acetate. To our knowledge, this is the first report on the biosynthesis of indole-3-ethanol and indole-3-ethanol acetate directly from a...
Source: Biochemical Engineering Journal - Category: Biochemistry Source Type: research
In this study, the systematic construction of metabolically engineered Escherichia coli strain for cytidine over-production was investigated, where the regulation of downstream pathway from uridine monophosphate (UMP) toward cytidine was focused on. Firstly, the engineered strain CR016 obtained by deleting the cytidine catabolism-related genes in E. coli MG1655 showed a significantly slower degradation rate of cytidine. Further modifications were carried out to amplify the metabolic flux from UMP to cytidine. The resulted strain CR023(pTrc03) began to accumulate 352.59 mg/L of cytidine in shake flask culture for 36&...
Source: Biochemical Engineering Journal - Category: Biochemistry Source Type: research
Possible mechanisms of the antimicrobial effects of polypeptide‑enriched Gastrodia elata Blume extracts. Mol Med Rep. 2019 Sep 25;: Authors: Kong F, Cai X, Zhai S, Wang R, Zheng X, Ma Y, Bi H, Wang D Abstract The present study aimed to evaluate the antimicrobial activity and the possible mechanisms of activity of polypeptide‑enriched Gastrodia elata extracts (GEP) against the gram‑negative bacteria Escherichia coli and Pseudomonas aeruginosa, the gram‑positive bacterium Staphylococcus aureus and the fungus Candida albicans. The antimicrobial activity of GEP was first confirmed by determining th...
Source: Molecular Medicine Reports - Category: Molecular Biology Tags: Mol Med Rep Source Type: research
Publication date: Available online 9 November 2019Source: Journal of Environmental SciencesAuthor(s): Weicheng Zhang, Bingyu Ning, Caiyun Sun, Ke Song, Xin Xu, Tao Fang, Lunguang YaoAbstractReleased Ag ions or/and Ag particles are believed to contribute to the cytotoxicity of Ag nanomaterials, and thus, the cytotoxicity and mechanism of Ag nanomaterials should be dynamic in water due to unfixed Ag particle:Ag+ ratios. Our recent research found that the cytotoxicity of PVP-Ag nanoparticles is attributable to Ag particles alone in 3 hr bioassays, and shifts to both Ag particles and released Ag+ in 48 hr bioassays. ...
Source: Journal of Environmental Sciences - Category: Environmental Health Source Type: research
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