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匹配条件： “ Christoph Syldatk” ，找到相关结果约6318条。
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Transaminases for the synthesis of enantiopure beta-amino acids
Jens Rudat, Birgit R Brucher, Christoph Syldatk
AMB Express , 2012, DOI: 10.1186/2191-0855-2-11

Abstract: Since the discovery of transamination in biological systems (Braunstein and Kritzmann 1937Moyle Needham 1930) the significance of transaminases (TAs) for amino acid metabolism has been the subject of intensive research. Over the last 15 years, TAs have gained increasing attention in organic synthesis for the biocatalytic production of a wide variety of chiral amines and α-amino acids. This has been discussed in detail in a series of excellent reviews (H？hne and Bornscheuer 2009; Koszelewski et al. 2010; Taylor et al. 1998; Ward and Wohlgemuth 2010). Advantages in the use of TAs lie in mostly low-cost substrates, no necessity for external cofactor recycling and the enzymes' high enantioselectivity and reaction rate. For the synthesis of enantiopure β-amino acids only a limited number of TAs are available. Therefore efficient screening techniques for TAs with high activities as well as broader substrate specificity and different enantioselectivities are crucial for the successful application of transaminases for the synthesis of β-amino acids. Of particular interest are methods that can be used at small scale compatible with microtiter plates.Enantiopure β-amino acids represent highly valuable building blocks for peptidomimetics and the synthesis of bioactive compounds. In order to distinguish positional isomers of β-amino acids, the terms β2-, β3- and β2,3-amino acids have been introduced by Seebach and coworkers (Hintermann and Seebach 1997; Seebach et al. 1997). With the exception of β-alanine and β-aminoisobutyric acid which constitute key intermediates in several metabolic pathways, β-amino acids are not as abundant in nature as α-amino acids. However, they occur as essential parts in a variety of biologically active compounds. Notable representatives are the antineoplastic agent paclitaxel (= Taxol？, Bristol-Myers Squibb) (Wani et al. 1971) and the chromophore of C-1027 (= lidamycin), a radiomimetic antitumor agent (Hu et al. 1988) (Figure 1a). β-Amino acids hav

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Novel amidases of two Aminobacter sp. strains: Biotransformation experiments and elucidation of gene sequences
Ulrike Engel, Christoph Syldatk, Jens Rudat
AMB Express , 2012, DOI: 10.1186/2191-0855-2-33

Abstract:

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Fast quantitative determination of microbial rhamnolipids from cultivation broths by ATR-FTIR Spectroscopy
Frank Leitermann, Christoph Syldatk, Rudolf Hausmann
Journal of Biological Engineering , 2008, DOI: 10.1186/1754-1611-2-13

Abstract: The rapid ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy) in time technique has been applied, which is suitable to quantify the concentrations of microbial rhamnolipids in a typical cultivation process. While the usually applied HPLC analysis requires an extensive and time consuming multi step extraction protocol for sample preparation, the ATR-FTIR-method allows the quantification of the rhamnolipids within 20 minutes. Accuracies between 0.5 g/l – 2.1 g/l for the different analytes were determined by cross validation of the calibration set. Even better accuracies between 0.28 g/l – 0.59 g/l were found for independent test samples of an arbitrarily selected cultivation.ATR-FTIR was found to be suitable for the rapid analysis of rhamnolipids in a biotechnological process with good reproducibility in sample determination and sufficient accuracy. An improvement in accuracy through continuous expansion and validation of the reference spectra set seems very likely.Ranging from bulk chemicals like ethanol to high value proteins, biotechnological production processes are an increasingly important manufacturing route for various products [1]. The control of these bioprocesses often can be considered as suboptimal. Usually only a few parameters, like pH, pO2 and temperature, are monitored online. All additional information required must be gained through analysis of individual samples. Typical assays often rely on enzymatic reactions or separation techniques such as high performance liquid chromatography (HPLC) [2]. Therefore, the analysis results often will be available only with a significant time delay.Hence, vibrational spectroscopic techniques that provide rapid and convenient solutions to routine analytical problems are being increasingly adopted. A variety of substances can be characterized, identified and also quantified rapidly in parallel from a single sample spectrum [3]. Fourier transform infrared spectroscopy (FTIR) is a reliable

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Separation of Cyclic Dipeptides (Diketopiperazines) from Their Corresponding Linear Dipeptides by RP-HPLC and Method Validation
Mareike Perzborn,Christoph Syldatk,Jens Rudat
Chromatography Research International , 2013, DOI: 10.1155/2013/310269

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Abstract: Simple, rapid, sensitive, precise, and accurate methods for detection and separation of seven diketopiperazines (DKPs), cyclo(Gly-Gly), cyclo(DL-Ala-DL-Ala), cyclo(L-Asp-L-Phe), cyclo(L-Asp-L-Asp), cyclo(Gly-L-Phe), cyclo(L-Pro-L-Tyr), and cyclo(L-Arg-L-Arg), from their corresponding linear dipeptides and related amino acids L-Phe and L-Tyr by reversed-phase high-performance liquid chromatography (RP-HPLC) were established. Moreover, for the racemic DKP cyclo(DL-Ala-DL-Ala) and dipeptide DL-Ala-DL-Ala, separation of the diastereomers was achieved. All methods can be performed within 15？min. For all DKPs, dipeptides, and amino acids, linear ranges with correlation coefficients greater than 0.998 were determined. Lowest limits of detection were found to be between 0.05 and 10？nmol per 10？μL injection, depending on the substance. For all tested substances intrarun and interrun precision ranged from 0.5 to 4.7% and 0.7 to 9.9% relative standard deviation, and accuracy was between ？4.2 and 8.1% relative error. Short-term and freeze-thaw stabilities were 93% or greater for all substances. Recovery rate after heat treatment was determined to be at least 97%. These methods will be useful for quantitative determination of DKPs and their potential biodegradation products: dipeptides and amino acids 1. Introduction Diketopiperazines (DKPs) are the smallest possible cyclic peptides composed of two -amino acids. They are abundant natural compounds produced by various bacteria like Streptomyces sp. [1], Pseudomonas aeruginosa [2], or Lactobacillus plantarum [3], fungi, e.g., Aspergillus flavus [4] or Alternaria alternata [5], and marine sponges like Dysidea herbacea [6]. Recently, the interest in this substance class has increased due to their immense bioactivities including antibacterial activity [7], antifungal function [3], cytotoxicity [4], phytotoxicity [5], and inhibition of plasminogen activator inhibitor-1 [8]. DKPs were shown to act as quorum sensing molecules; e.g., cyclo(L-Pro-L-Tyr), used in this study, was identified in culture supernatant of Pseudomonas aeruginosa and was identified as an activator of an N-acylhomoserine lactone biosensor [2]. Besides their widespread biosynthesis in nature, DKPs occur as chemical degradation products of, for example, amoxicillin, an aminopenicillin antibiotic [9], neuropeptide substance P [10], angiotensin converting enzyme inhibitor enalapril [11], or the sweetener aspartame with cyclo(L-Asp-L-Phe) as degradation product [12–17]. Amoxicillin and especially its degradation products can be detected in aquatic

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Process development for the elucidation of mycotoxin formation in Alternaria alternata
Katrin Brzonkalik, Tanja Herrling, Christoph Syldatk, Anke Neumann
AMB Express , 2011, DOI: 10.1186/2191-0855-1-27

Abstract: In this system the effect of different aeration rates (0.53 vvm-0.013 vvm) was tested which exerted a great influence on mycotoxin production. The use of the semi-synthetic Czapek-Dox medium allowed the exchange of carbon and nitrogen sources for acetate and aspartic acid. The use of acetate instead of glucose resulted in the sole production of alternariol whereas the exchange of ammonium and nitrate for aspartate enhanced the production of both AOH and AME while TA production was not affected.Mycotoxins are secondary metabolites of low molecular weight produced by filamentous fungi. Since the discovery of the first mycotoxins, the aflatoxins, in 1960 which caused the death of 10,000 turkeys many new mycotoxins have been identified in the last 50 years. Today 300 to 400 compounds are designated as mycotoxins (Bennett and Klich 2003). As other secondary metabolites mycotoxins are formed subsequently to the growth phase and are not necessary for growth or development (Fox and Howlett 2008). Mycotoxin formation is subjected to a complex regulation, but it is often induced by nutrient limitation (Demain 1986). Mycotoxins are released by the fungus in the surrounding substrate and contamination of agricultural products is therefore possible. They are connected to certain health disorders and elicit acute toxic, mutagenic, teratogenic, carcinogenic and sometimes estrogenic properties (Bhatnagar et al. 2002). Based on estimations of the Food and Agriculture Organization (FAO) of the United Nations approximately 25% of the world's food crops are affected by mycotoxin producing fungi and global losses of foodstuffs due to mycotoxins are in the range of 1000 million tons per year http://www.fao.org/ag/agn/agns/chemicals_mycotoxins_en.asp webcite.Alternaria species are wide spread black moulds which belong to the division of Deuteromycota (Bottalico and Logrieco 1998) and are common saprophytes found on decaying organic material world-wide. The genus Alternaria includes also o

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Influence of pH and carbon to nitrogen ratio on mycotoxin production by Alternaria alternata in submerged cultivation
Katrin Brzonkalik, Dominik Hümmer, Christoph Syldatk, Anke Neumann
AMB Express , 2012, DOI: 10.1186/2191-0855-2-28

Abstract:

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Toward a cell-free hydantoinase process: screening for expression optimization and one-step purification as well as immobilization of hydantoinase and carbamoylase
Christin Slomka,Christof M. Niemeyer,Christoph Syldatk,Georg Paris Sp？th,Marc Skoupi,Phillip Lemke
- , 2017, DOI: 10.1186/s13568-017-0420-3

Abstract: The hydantoinase process is applied for the industrial synthesis of optically pure amino acids via whole cell biocatalysis, providing a simple and well-established method to obtain the catalyst. Nevertheless, whole cell approaches also bear disadvantages like intracellular degradation reactions, transport limitations as well as low substrate solubility. In this work the hydantoinase and carbamoylase from Arthrobacter crystallopoietes DSM 20117 were investigated with respect to their applicability in a cell-free hydantoinase process. Both enzymes were heterologously expressed in Escherichia coli BL21DE3. Cultivation and induction of the hydantoinase under oxygen deficiency resulted in markedly higher specific activities and a further increase in expression was achieved by codon-optimization. Further expression conditions of the hydantoinase were tested using the microbioreactor system BioLector？, which showed a positive effect upon the addition of 3% ethanol to the cultivation medium. Additionally, the hydantoinase and carbamoylase were successfully purified by immobilized metal ion affinity using Ni Sepharose beads as well as by functionalized magnetic beads, while the latter method was clearly more effective with respect to recovery and purification factor. Immobilization of both enzymes via functionalized magnetic beads directly from the crude cell extract was successful and resulted in specific activities that turned out to be much higher than those of the purified free enzymes

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Growth independent rhamnolipid production from glucose using the non-pathogenic Pseudomonas putida KT2440
Andreas Wittgens, Till Tiso, Torsten T Arndt, Pamela Wenk, Johannes Hemmerich, Carsten Müller, Rolf Wichmann, Benjamin Küpper, Michaela Zwick, Susanne Wilhelm, Rudolf Hausmann, Christoph Syldatk, Frank Rosenau, Lars M Blank
Microbial Cell Factories , 2011, DOI: 10.1186/1475-2859-10-80

Abstract: Here, the metabolic engineering of a rhamnolipid producing Pseudomonas putida KT2440, a strain certified as safety strain using glucose as carbon source to avoid cumbersome product purification, is reported. Notably, P. putida KT2440 features almost no changes in growth rate and lag-phase in the presence of high concentrations of rhamnolipids (> 90 g/L) in contrast to the industrially important bacteria Bacillus subtilis, Corynebacterium glutamicum, and Escherichia coli. P. putida KT2440 expressing the rhlAB-genes from P. aeruginosa PAO1 produces mono-rhamnolipids of P. aeruginosa PAO1 type (mainly C10:C10). The metabolic network was optimized in silico for rhamnolipid synthesis from glucose. In addition, a first genetic optimization, the removal of polyhydroxyalkanoate formation as competing pathway, was implemented. The final strain had production rates in the range of P. aeruginosa PAO1 at yields of about 0.15 g/gglucose corresponding to 32% of the theoretical optimum. What's more, rhamnolipid production was independent from biomass formation, a trait that can be exploited for high rhamnolipid production without high biomass formation.A functional alternative to the pathogenic rhamnolipid producer P. aeruginosa was constructed and characterized. P. putida KT24C1 pVLT31_rhlAB featured the highest yield and titer reported from heterologous rhamnolipid producers with glucose as carbon source. Notably, rhamnolipid production was uncoupled from biomass formation, which allows optimal distribution of resources towards rhamnolipid synthesis. The results are discussed in the context of rational strain engineering by using the concepts of synthetic biology like chassis cells and orthogonality, thereby avoiding the complex regulatory programs of rhamnolipid production existing in the natural producer P. aeruginosa.Rhamnolipids are biosurfactants with high industrial potential. The possible applications are manifold, as reviewed by Lang and Wullbrandt [1] and Maier and Sobe

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High Quality Draft Genomes of the Type Strains Geobacillus thermocatenulatus DSM 730T, G. uzenensis DSM 23175T And Parageobacillus galactosidasius DSM 18751T
Anke Neumann,Christoph Syldatk,Daniel Ray Zeigler,Don Arthur Cowan,Florian Oswald,Habibu Aliyu,Michaela Zwick,Nadine Koen,Pedro Humberto Lebre,Pieter De Maayer,Shamara Polliack,Teresa Mohr,Winnie Thabisa Ramaloko
- , 2018, DOI: 10.7150/jgen.22986

Abstract: The thermophilic 'Geobacilli' are important sources of thermostable enzymes and other biotechnologically relevant macromolecules. The present work reports the high quality draft genome sequences of previously unsequenced type strains of Geobacillus uzenensis (DSM 23175T), G. thermocatenulatus (DSM 730T) and Parageobacillus galactosidasius (DSM 18751T). Phylogenomic analyses revealed that DSM 18751T and DSM 23175T represent later heterotypic synonyms of P. toebii and G. subterraneus, respectively, while DSM 730T represents the type strain for the species G. thermocatenulatus. These genome sequences will contribute towards a deeper understanding of the ecological and biological diversity and the biotechnological exploitation of the 'geobacilli'.

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