@article{DeppeKlatteBongaertsetal.2011, author = {Deppe, Veronika Maria and Klatte, Stephanie and Bongaerts, Johannes and Maurer, Karl-Heinz and O'Connell, Timothy and Meinhardt, Friedhelm}, title = {Genetic control of Amadori product degradation in Bacillus subtilis via regulation of frlBONMD expression by FrlR}, series = {Applied and environmental microbiology}, volume = {Vol. 77}, journal = {Applied and environmental microbiology}, number = {No. 9}, publisher = {American Society of Mechanical Engineers (ASME)}, address = {New York}, issn = {1098-5336 (E-Journal); 0003-6919 (Print); 0099-2240 (Print)}, pages = {2839 -- 2846}, year = {2011}, language = {en} } @incollection{FrotscherGossmannRaatschenetal.2015, author = {Frotscher, Ralf and Goßmann, Matthias and Raatschen, Hans-J{\"u}rgen and Temiz Artmann, Ayseg{\"u}l and Staat, Manfred}, title = {Simulation of cardiac cell-seeded membranes using the edge-based smoothed FEM}, series = {Shell and membrane theories in mechanics and biology. (Advanced structured materials ; 45)}, booktitle = {Shell and membrane theories in mechanics and biology. (Advanced structured materials ; 45)}, publisher = {Springer}, address = {Heidelberg}, isbn = {978-3-319-02534-6 ; 978-3-319-02535-3}, pages = {187 -- 212}, year = {2015}, abstract = {We present an electromechanically coupled Finite Element model for cardiac tissue. It bases on the mechanical model for cardiac tissue of Hunter et al. that we couple to the McAllister-Noble-Tsien electrophysiological model of purkinje fibre cells. The corresponding system of ordinary differential equations is implemented on the level of the constitutive equations in a geometrically and physically nonlinear version of the so-called edge-based smoothed FEM for plates. Mechanical material parameters are determined from our own pressure-deflection experimental setup. The main purpose of the model is to further examine the experimental results not only on mechanical but also on electrophysiological level down to ion channel gates. Moreover, we present first drug treatment simulations and validate the model with respect to the experiments.}, language = {en} } @inproceedings{EngelThieringerTippkoetter2016, author = {Engel, M. and Thieringer, J. and Tippk{\"o}tter, Nils}, title = {Microbial electrosynthesis for sustainable biobutanol production}, series = {New frontiers of biotech-processes (Himmelfahrtstagung) : 02-04 May 2016, Rhein-Mosel-Halle, Koblenz/Germany}, booktitle = {New frontiers of biotech-processes (Himmelfahrtstagung) : 02-04 May 2016, Rhein-Mosel-Halle, Koblenz/Germany}, publisher = {DECHEMA}, address = {Frankfurt am Main}, pages = {77 -- 78}, year = {2016}, language = {en} } @article{BorgmeierBongaertsMeinhardt2012, author = {Borgmeier, Claudia and Bongaerts, Johannes and Meinhardt, Friedhelm}, title = {Genetic analysis of the Bacillus licheniformis degSU operon and the impact of regulatory mutations on protease production}, series = {Journal of biotechnology}, volume = {159}, journal = {Journal of biotechnology}, number = {1-2}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-4863 (E-Journal); 0168-1656 (Print)}, doi = {10.1016/j.jbiotec.2012.02.011}, pages = {12 -- 20}, year = {2012}, abstract = {Disruption experiments targeted at the Bacillus licheniformis degSU operon and GFP-reporter analysis provided evidence for promoter activity immediately upstream of degU. pMutin mediated concomitant introduction of the degU32 allele - known to cause hypersecretion in Bacillus subtilis - resulted in a marked increase in protease activity. Application of 5-fluorouracil based counterselection through establishment of a phosphoribosyltransferase deficient Δupp strain eventually facilitated the marker-free introduction of degU32 leading to further protease enhancement achieving levels as for hypersecreting wild strains in which degU was overexpressed. Surprisingly, deletion of rapG - known to interfere with DegU DNA-binding in B. subtilis - did not enhance protease production neither in the wild type nor in the degU32 strain. The combination of degU32 and Δupp counterselection in the type strain is not only equally effective as in hypersecreting wild strains with respect to protease production but furthermore facilitates genetic strain improvement aiming at biological containment and effectiveness of biotechnological processes.}, language = {en} } @article{MolinnusSorichBartzetal.2016, author = {Molinnus, Denise and Sorich, Maren and Bartz, Alexander and Siegert, Petra and Willenberg, Holger S. and Lisdat, Fred and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Towards an adrenaline biosensor based on substrate recycling amplification in combination with an enzyme logic gate}, series = {Sensors and Actuators B: Chemical}, volume = {237}, journal = {Sensors and Actuators B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2016.06.064}, pages = {190 -- 195}, year = {2016}, abstract = {An amperometric biosensor using a substrate recycling principle was realized for the detection of low adrenaline concentrations (1 nM) by measurements in phosphate buffer and Ringer's solution at pH 6.5 and pH 7.4, respectively. In proof-of-concept experiments, a Boolean logic-gate principle has been applied to develop a digital adrenaline biosensor based on an enzyme AND logic gate. The obtained results demonstrate that the developed digital biosensor is capable for a rapid qualitative determination of the presence/absence of adrenaline in a YES/NO statement. Such digital biosensor could be used in clinical diagnostics for the control of a correct insertion of a catheter in the adrenal veins during adrenal venous-sampling procedure.}, language = {en} } @article{BaeckerBegingBisellietal.2009, author = {B{\"a}cker, Matthias and Beging, Stefan and Biselli, Manfred and Poghossian, Arshak and Wang, J. and Zang, Werner and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Concept for a solid-state multi-parameter sensor system for cell-culture monitoring}, series = {Electrochimica Acta. 54 (2009), H. 25 Sp. Iss. SI}, journal = {Electrochimica Acta. 54 (2009), H. 25 Sp. Iss. SI}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {0013-4686}, pages = {6107 -- 6112}, year = {2009}, language = {en} } @article{HuckSchiffelsHerreraetal.2013, author = {Huck, Christina and Schiffels, Johannes and Herrera, Cony N. and Schelden, Maximilian and Selmer, Thorsten and Poghossian, Arshak and Baumann, Marcus and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Metabolic responses of Escherichia coli upon glucose pulses captured by a capacitive field-effect sensor}, series = {Physica Status Solidi (A)}, volume = {210}, journal = {Physica Status Solidi (A)}, number = {5}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0031-8965}, doi = {10.1002/pssa.201200900}, pages = {926 -- 931}, year = {2013}, abstract = {Living cells are complex biological systems transforming metabolites taken up from the surrounding medium. Monitoring the responses of such cells to certain substrate concentrations is a challenging task and offers possibilities to gain insight into the vitality of a community influenced by the growth environment. Cell-based sensors represent a promising platform for monitoring the metabolic activity and thus, the "welfare" of relevant organisms. In the present study, metabolic responses of the model bacterium Escherichia coli in suspension, layered onto a capacitive field-effect structure, were examined to pulses of glucose in the concentration range between 0.05 and 2 mM. It was found that acidification of the surrounding medium takes place immediately after glucose addition and follows Michaelis-Menten kinetic behavior as a function of the glucose concentration. In future, the presented setup can, therefore, be used to study substrate specificities on the enzymatic level and may as well be used to perform investigations of more complex metabolic responses. Conclusions and perspectives highlighting this system are discussed.}, language = {en} } @article{ThielTippkoetterSucketal.2013, author = {Thiel, Alexander and Tippk{\"o}tter, Nils and Suck, Kirstin and Sohling, Ulrich and Ruf, Friedrich and Ulber, Roland}, title = {New zeolite adsorbents for downstream processing of polyphenols from renewable resources}, series = {Engineering in Life Sciences}, volume = {13}, journal = {Engineering in Life Sciences}, number = {3}, publisher = {Wiley}, address = {Weinheim}, doi = {10.1002/elsc.201200188}, pages = {239 -- 246}, year = {2013}, abstract = {Commercial materials with polyvinylpolypyrrolidone and polymeric amberlites (XAD7HP, XAD16) are commonly used for the adsorptive downstream processing of polyphenols from renewable resources. In this study, beta-zeolite-based adsorbent systems were examined, and their properties were compared to organic resins. Batch adsorption experiments were conducted with synthetic solutions of major polyphenols. Adsorption isotherms and desorption characteristics of individual adsorbent were determined based on these results. Maximum adsorption capacities were calculated using the Langmuir model. For example, the zeolites had capacities up to 203.2 mg/g for ferulic acid. To extend these results to a complex system, additional experiments were performed on rapeseed meal and wheat seed extracts as representative renewable resources. HPLC analysis showed that with 7.5\% w/v, which is regarded as the optimum amount of zeolites, zeolites A and B could bind 100\% of the major polyphenols as well as release polyphenols at high yields. Additionally, regeneration experiments were performed with isopropyl alcohol at 99°C to evaluate how zeolites regenerate under mild conditions. The results showed only a negligible loss of adsorption capacity and no loss of desorption capacity. In summary, it was concluded that beta-zeolites were promising adsorbents for developing new processes to isolate polyphenols from renewable resources.}, language = {en} } @article{TippkoetterDuweWiesenetal.2014, author = {Tippk{\"o}tter, Nils and Duwe, Anna-Maria and Wiesen, Sebastian and Sieker, Tim and Ulber, Roland}, title = {Enzymatic hydrolysis of beech wood lignocellulose at high solid contents and its utilization as substrate for the production of biobutanol and dicarboxylic acids}, series = {Bioresource Technology}, volume = {167}, journal = {Bioresource Technology}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.biortech.2014.06.052}, pages = {447 -- 455}, year = {2014}, abstract = {The development of a cost-effective hydrolysis for crude cellulose is an essential part of biorefinery developments. To establish such high solid hydrolysis, a new solid state reactor with static mixing is used. However, concentrations >10\% (w/w) cause a rate and yield reduction of enzymatic hydrolysis. By optimizing the synergetic activity of cellulolytic enzymes at solid concentrations of 9\%, 17\% and 23\% (w/w) of crude Organosolv cellulose, glucose concentrations of 57, 113 and 152 g L⁻¹ are reached. However, the glucose yield decreases from 0.81 to 0.72gg⁻¹ at 17\% (w/w). Optimal conditions for hydrolysis scale-up under minimal enzyme addition are identified. As result, at 23\% (w/w) crude cellulose the glucose yield increases from 0.29 to 0.49gg⁻¹. As proof of its applicability, biobutanol, succinic and itaconic acid are produced with the crude hydrolysate. The potential of the substrate is proven e.g. by a high butanol yield of 0.33gg⁻¹.}, language = {en} } @article{TippkoetterWollnySucketal.2014, author = {Tippk{\"o}tter, Nils and Wollny, Steffen and Suck, Kirstin and Sohling, Ulrich and Ruf, Friedrich and Ulber, Roland}, title = {Recycling of spent oil bleaching earth as source of glycerol for the anaerobic production of acetone, butanol, and ethanol with Clostridium diolis and lipolytic Clostridium lundense}, series = {Engineering in Life Sciences}, volume = {14}, journal = {Engineering in Life Sciences}, number = {4}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1618-2863}, doi = {10.1002/elsc.201300113}, pages = {425 -- 432}, year = {2014}, abstract = {A major part of edible oil is subjected to bleaching procedures, primarily with minerals applied as adsorbers. Their recycling is currently done either by regaining the oil via organic solvent extraction or by using the spent bleaching earth (SBE) as additive for animal feed, etc. As a new method, the reutilization of the by-product SBE for the microbiologic formation of acetone, butanol, and ethanol (ABE) is presented as proof-of-concept. The SBE was taken from a palm oil cleaning process. The recycling concept is based on the application of lipolytic clostridia strains. Due to considerably long fermentation times, co-fermentation with Candida rugosa and enzymatic hydrolyses of the bound oil with a subsequent clostridia fermentation are shown as alternative routes. Anaerobic fermentations under comparison of different clostridia strains were performed with glycerol media, enzymatically hydrolyzed palm oil and SBE. Solutes, side product compositions and productivities were quantified via HPLC. A successful production of ABE solutes from SBE has been done with a yield of 0.15 g butanol per gram of bound glycerol. Thus, the biotechnological recycling of the waste stream is possible in principle. Inhibition of the substrate suspension has been observed. A chromatographic ion-exchange of substrates increased the biomass concentration.}, language = {en} }