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Biberach an der Riss, Germany

Straub M.,University of Ulm | Straub M.,Biberach University of Applied Sciences | Demler M.,TU Munich | Weuster-Botz D.,TU Munich | Durre P.,University of Ulm
Journal of Biotechnology | Year: 2014

Great interest has emerged in the recent past towards the potential of autotrophic acetogenic bacteria for the sustainable production of fuels and chemicals. This group of microorganisms possesses an ancient pathway for the fixation of carbon dioxide in the presence of hydrogen, making them highly attractive for the utilization of gas mixtures as a cheap and abundant carbon and energy source. As more and more genome sequence data of acetogens becomes available, the genetic tools are being developed concomitantly. Here, we demonstrate for the first time the genetic modification of the well-characterized acetogen Acetobacterium woodii. This microorganism selectively produces acetate under autotrophic conditions, but seems to be limited at high acetate concentrations. To increase the carbon flow through the Wood-Ljungdahl pathway and therefore increase the efficiency of CO2 fixation, genes of enzyme groups of this pathway were selectively overexpressed (the four THF-dependent enzymes for the processing of formate as well as phosphotransacetylase and acetate kinase to enhance an ATP-generation step). Acetate production with genetically modified strains was increased in a batch process under pH-controlled reaction conditions in a stirred-tank reactor with continuous sparging of H2 and CO2. Final acetate concentrations of more than 50gL-1 acetate were thus measured with the recombinant strains at low cell concentrations of 1.5-2gL-1 dry cell mass in less than four days under autotrophic conditions. © 2014 Elsevier B.V. Source

Kaysser L.,University of Tubingen | Siebenberg S.,University of Tubingen | Kammerer B.,Biberach University of Applied Sciences | Gust B.,University of Tubingen
ChemBioChem | Year: 2010

En route: The liposidomycin biosynthetic gene cluster has been identified, cloned and heterologously expressed. A comparison with the gene cluster of the structurally related caprazamycins supports the proposed pathway to liponucleoside formation and led to the identification of new sulfated caprazamycin derivatives. (Chemical Equation Presented). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA. Source

Carius L.,Max Planck Institute for Dynamics of Complex Technical Systems | Carius A.B.,Max Planck Institute for Dynamics of Complex Technical Systems | McIntosh M.,University of Marburg | Grammel H.,Max Planck Institute for Dynamics of Complex Technical Systems | Grammel H.,Biberach University of Applied Sciences
BMC Microbiology | Year: 2013

Background: The facultative anoxygenic photosynthetic bacterium Rhodospirillum rubrum exhibits versatile metabolic activity allowing the adaptation to rapidly changing growth conditions in its natural habitat, the microaerobic and anoxic zones of stagnant waters. The microaerobic growth mode is of special interest as it allows the high-level expression of photosynthetic membranes when grown on succinate and fructose in the dark, which could significantly simplify the industrial production of compounds associated with PM formation. However, recently we showed that PM synthesis is no longer inducible when R. rubrum cultures are grown to high cell densities under aerobic conditions. In addition a reduction of the growth rate and the continued accumulation of precursor molecules for bacteriochlorophyll synthesis were observed under high cell densities conditions. Results: In the present work, we demonstrate that the cell density-dependent effects are reversible if the culture supernatant is replaced by fresh medium. We identified six N-acylhomoserine lactones and show that four of them are produced in varying amounts according to the growth phase and the applied growth conditions. Further, we demonstrate that N-acylhomoserine lactones and tetrapyrrole compounds released into the growth medium affect the growth rate and PM expression in high cell density cultures. Conclusions: In summary, we provide evidence that R. rubrum possesses a Lux-type quorum sensing system which influences the biosynthesis of PM and the growth rate and is thus likely to be involved in the phenotypes of high cell density cultures and the rapid adaptation to changing environmental conditions. © 2013 Carius et al.; licensee BioMed Central Ltd. Source

Henze G.P.,University of Colorado at Boulder | Floss A.G.,Biberach University of Applied Sciences
Energy and Buildings | Year: 2011

The degradation of the temperature difference between supply and return flow reduces the efficiency of chilled water systems as well as central heating systems. In both applications, the problem is caused by excessive water flow rates under part load conditions and equipment oversizing. Remedies to address this ΔT degradation by reducing bypass flow have been recommended and documented over the last 25 years, especially in the field of chilled water systems. This paper addresses ΔT degradation caused by a set of common faults: hydraulic network imbalance, control valve oversizing, incorrect inherent valve characteristic, and inadequate control loop gain parameters. To allow for the quantitative evaluation of the numerous possible causes that contribute to ΔT degradation, a dynamic simulation environment was developed and employed in the presented analysis that couples pressure-flow relationships in the hydraulic network with the dynamic thermal loads of the building under investigation. Relative to the reference case of a properly designed and tuned hydraulic subsystem, a ΔT degradation of over 6 K in a sample central heating system is predicted, well aligned with commissioning reports of large chilled water and district heating plants. In district heating systems, this significant ΔT degradation of 6 K would lead to an increase of the primary energy consumption between 4 and 12%. © 2011 Elsevier B.V. All rights reserved. Source

Fischer S.,Biberach University of Applied Sciences | Fischer S.,University of Ulm | Handrick R.,Biberach University of Applied Sciences | Aschrafi A.,Radboud University Nijmegen | Otte K.,Biberach University of Applied Sciences
RNA Biology | Year: 2015

Understanding the multifaceted nature of microRNA (miRNA) function in mammalian cells is still a challenge. Commonly accepted principles of cooperativity and multiplicity of miRNA function imply that individual mRNAs can be targeted by several miRNAs whereas a single miRNA may concomitantly regulate a subset of different genes. However, there is a paucity of information whether multiple miRNAs regulate critical cellular events and thereby acting redundantly. To gain insight into this notion, we conducted an unbiased high-content miRNA screen by individually introducing 1139 miRNA mimics into Chinese hamster ovary (CHO) cells. We discovered that 66% of all miRNAs significantly impacted on proliferation, protein expression, apoptosis and necrosis. In summary, we provide evidence for a substantial degree of redundancy among miRNAs to maintain cellular homeostasis. © 2015 Taylor & Francis Group, LLC. Source

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