TY  - INPR
A1  - Greiner, Lasse
A1  - Jeromin, Günter Erich
A1  - Sithole, Patience
A1  - Petersen, Soenke
T1  - Preprint: Studies on the enzymatic reduction of levulinic acid using Chiralidon-R and Chiralidon-S
T2  - ChemRxiv
N2  - The enzymatic reduction of levulinic acid by the chiral catalysts Chiralidon-R and Chiralidon-S which are commercially available superabsorbed alcohol dehydrogenases is described. The Chiralidon®-R/S reduces the levulinic acid to the (R,S)-4-hydroxy valeric acid and the (R)- or (S)- gamma-valerolactone.
KW  - Levulinic acid
KW  - Chiralidon-R
KW  - Chiralidon-S
KW  - 4-hydroxy valeric acid
KW  - (R)- or (S)- gamma-valerolactone
Y1  - 2023
U6  - https://doi.org/10.26434/chemrxiv-2023-jlvcv
ER  - 
TY  - JOUR
A1  - El Bergui, Omnia
A1  - Abouabdillah, Aziz
A1  - Bourioug, Mohamed
A1  - Schmitz, Dominik
A1  - Biel, Markus
A1  - Aboudrare, Abdellah
A1  - Krauss, Manuel
A1  - Jomaa, Ahlem
A1  - Romuli, Sebastian
A1  - Müller, Joachim
A1  - Fagroud, Mustapha
A1  - Bouabid, Rachid
T1  - Innovative solutions for drought: Evaluating hydrogel application on onion cultivation (Allium cepa) in Morocco
JF  - Water
N2  - Throughout the last decade, and particularly in 2022, water scarcity has become a critical concern in Morocco and other Mediterranean countries. The lack of rainfall during spring was worsened by a succession of heat waves during the summer. To address this drought, innovative solutions, including the use of new technologies such as hydrogels, will be essential to transform agriculture. This paper presents the findings of a study that evaluated the impact of hydrogel application on onion (Allium cepa) cultivation in Meknes, Morocco. The treatments investigated in this study comprised two different types of hydrogel-based soil additives (Arbovit® polyacrylate and Huminsorb® polyacrylate), applied at two rates (30 and 20 kg/ha), and irrigated at two levels of water supply (100% and 50% of daily crop evapotranspiration; ETc). Two control treatments were included, without hydrogel application and with both water amounts. The experiment was conducted in an open field using a completely randomized design. The results indicated a significant impact of both hydrogel-type dose and water dose on onion plant growth, as evidenced by various vegetation parameters. Among the hydrogels tested, Huminsorb® Polyacrylate produced the most favorable outcomes, with treatment T9 (100%, HP, 30 kg/ha) yielding 70.55 t/ha; this represented an increase of 11 t/ha as compared to the 100% ETc treatment without hydrogel application. Moreover, the combination of hydrogel application with 50% ETc water stress showed promising results, with treatment T4 (HP, 30 kg, 50%) producing almost the same yield as the 100% ETc treatment without hydrogel while saving 208 mm of water.
KW  - water economy
KW  - yield
KW  - deficit irrigation
KW  - hydrogel
KW  - onion
Y1  - 2023
U6  - https://doi.org/10.3390/w15111972
VL  - 15
IS  - 11
PB  - MDPI
CY  - Basel
ER  - 
TY  - GEN
A1  - Braun, Lena
A1  - Krafft, Simone
A1  - Tippkötter, Nils
T1  - Combined supercritical carbon dioxide extraction and chromatography of the algae fatty linoleic and linolenic acid
T2  - Chemie Ingenieur Technik
N2  - A method for the integrated extraction and separation of fatty acids from algae using supercritical CO2 is presented. Desmodesmus obliquus and Chlorella sorokiniana were used as algae. First, a method for chromatographic separation of fatty acids of different degrees of saturation was established and optimized. Then, an integrated method for supercritical extraction was developed for both algal species. It was also verified whether prior cell disruption was beneficial for extraction. In developing the method for chromatographic separation, statistical experimental design was used to determine the optimal parameter settings. The methanol content in the mobile phase proved to be the most important parameter for successful separation of the three unsaturated fatty acids oleic acid, linoleic acid, and linolenic acid. Supercritical extraction with dried algae showed that about four times more fatty acids can be extracted from C. sorokiniana relative to the dry mass used.
Y1  - 2022
U6  - https://doi.org/10.1002/cite.202255308
SN  - 0009-286X
SN  - 1522-2640 (eISSN)
N1  - ProcessNet and DECHEMA‐BioTechNet Jahrestagungen 2022 together with 13th ESBES Symposium 2022, 12. - 15. September 2022, Eurogress Aachen
VL  - 94
IS  - 9
SP  - 1304
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - GEN
A1  - Krafft, Simone
A1  - Kuka, Katrin
A1  - Ulber, Roland
A1  - Tippkötter, Nils
T1  - Utilization of Lolium perenne varieties as a renewable substrate for single-cell proteins, lactate, and composite materials
T2  - Chemie Ingenieur Technik
N2  - Lolium perenne (perennial ryegrass) is aproductive and high-quality forage grass indigenous to Southern Europe, temperate Asia, and North Africa. Nowadays it is widespread and the dominant grass species on green areas in temperate climates. This abundant source of biomass is suitable for the development of bioeconomic processes because of its high cellulose and water-soluble carbohydrate content. In this work, novel breeds of the perennial ryegrass are being examined with regards to their quality parameters and biotechnological utilization options within the context of bioeconomy. Three processing operations are presented. In the first process, the perennial ryegrass is pretreated by pressing or hydrothermal extraction to derive glucosevia subsequent enzymatic hydrolysis of cellulose. A yield of up to 82 % glucose was achieved when using the hydrothermal ex-traction as pretreatment. In a second process, the ryegrass is used to produce lactic acid in high concentrations. The influence of the growth conditions and the cutting time on the carboxylic acid yield is investigated. A yield of lactic acid of above 150 g kg⁻¹  dry matter was achieved. The third process is to use Lolium perenne as a substrate in the fermentation of K. marxianus for the microbial production of single-cell proteins. The perennial ryegrass is screw-pressed and the press juice is used as medium. When supplementing the press juice with yeast media components, a biomass concentration of up to 16 g L⁻¹ could be achieved.
Y1  - 2022
U6  - https://doi.org/10.1002/cite.202255306
SN  - 0009-286X
SN  - 1522-2640 (eISSN)
N1  - ProcessNet and DECHEMA‐BioTechNet Jahrestagungen 2022 together with 13th ESBES Symposium 2022, 12. - 15. September 2022, Eurogress Aachen
VL  - 94
IS  - 9
SP  - 1303
EP  - 1304
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - GEN
A1  - Varriale, Ludovica
A1  - Kuka, Katrin
A1  - Tippkötter, Nils
A1  - Ulber, Roland
T1  - Use of a green biomass in a biorefinery platform
T2  - Chemie Ingenieur Technik
N2  - The emerging environmental issues due to the use of fossil resources are encouraging the exploration of new renewable resources. Biomasses are attracting more interest due to the low environmental impacts, low costs, and high availability on earth. In this scenario, green biorefineries are a promising platform in which green biomasses are used as feedstock. Grasses are mainly composed of cellulose and hemicellulose, and lignin is available in a small amount. In this work, a perennial ryegrass was used as feedstock to develop a green bio-refinery platform. Firstly, the grass was mechanically pretreated, thus obtaining a press juice and a press cake fraction. The press juice has high nutritional values and can be employed as part of fermentation media. The press cake can be employed as a substrate either in enzymatic hydrolysis or in solid-state fermentation. The overall aim of this work was to demonstrate different applications of both the liquid and the solid fractions. For this purpose, the filamentous fungus A. niger and the yeast Y. lipolythica were selected for their ability to produce citric acid. Finally, the possibility was assessed to use the press juice as part of fermentation media to cultivate S. cerevisiae and lactic acid bacteria for ethanol and lactic acid fermentation.
Y1  - 2022
U6  - https://doi.org/10.1002/cite.202255095
SN  - 0009-286X
SN  - 1522-2640 (eISSN)
N1  - ProcessNet and DECHEMA‐BioTechNet Jahrestagungen 2022 together with 13th ESBES Symposium 2022, 12. - 15. September 2022, Eurogress Aachen
VL  - 94
IS  - 9
SP  - 1299
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - GEN
A1  - Rothkranz, Berit
A1  - Krafft, Simone
A1  - Tippkötter, Nils
T1  - Media optimization for sustainable fuel production: How to produce biohydrogen from renewable resources with Thermotoga neapolitana
T2  - Chemie Ingenieur Technik
N2  - Hydrogen is playing an increasingly important role in research and politics as an energy carrier of the future. Since hydrogen has commonly been produced from methane by steam reforming, the need for climate-friendly, alternative production routes is emerging. In addition to electrolysis, fermentative routes for the production of so-called biohydrogen are "green" alternatives. The application of microorganisms offers the advantage of sustainable production from renewable resources using easily manageable technologies. In this project, the hyperthermophilic, anaerobic microorganism Thermotoga neapolitana is used for the productio nof biohydrogen from renewable resources. The enzymatically hydrolyzed resources were used in fermentation leading to yield coefficients of 1.8 mole H₂ per mole glucose when using hydrolyzed straw and ryegrass supplemented with medium, respectively. These results are similar to the hydrogen yields when using Thermotoga basal medium with glucose (TBGY) as control group. In order to minimize the supplementation of the hydrolysate and thus increase the economic efficiency of the process, the essential media components were identified. The experiments revealed NaCl, KCl, and glucose as essential components for cell growth as well as biohydrogen production. When excluding NaCl, a decrease of 96% in hydrogen production occured.
Y1  - 2022
U6  - https://doi.org/10.1002/cite.202255305
SN  - 0009-286X
SN  - 1522-2640 (eISSN)
N1  - ProcessNet and DECHEMA‐BioTechNet Jahrestagungen 2022 together with 13th ESBES Symposium 2022, 12. - 15. September 2022, Eurogress Aachen
VL  - 94
IS  - 9
SP  - 1298
EP  - 1299
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - CHAP
A1  - Engel, Mareike
A1  - Thieringer, Julia
A1  - Tippkötter, Nils
T1  - Linking bioprocess engineering and electrochemistry for sustainable biofuel production
T2  - Young Researchers Symposium, YRS 2016. Proceedings
N2  - Electromicrobial engineering is an emerging, highly interdisciplinary research area linking bioprocesses with electrochemistry. In this work, microbial electrosynthesis (MES) of biobutanol is carried out during acetone-butanol-ethanol (ABE) fermentations with Clostridium acetobutylicum. A constant electric potential of −600mV (vs. Ag/AgCl) with simultaneous addition of the soluble redox mediator neutral red is used in order to study the electron transfer between the working electrode and the bacterial cells. The results show an earlier initiation of solvent production for all fermentations with applied potential compared to the conventional ABE fermentation. The f inal butanol concentration can be more than doubled by the application of a negative potential combined with addition of neutral red. Moreover a higher biofilm formation on the working electrode compared to control cultivations has been observed. In contrast to previous studies, our results also indicate that direct electron transfer (DET) might be possible with C. acetobutylicum. The presented results make microbial butanol production economically attractive and therefore support the development of sustainable production processes in the chemical industry aspired by the “Centre for resource-efficient chemistry and raw material change” as well as the the project “NanoKat” working on nanostructured catalysts in Kaiserslautern.
Y1  - 2016
N1  - Young Researchers Symposium, YRS 2016, 14th - 15th April 2016, Fraunhofer-Zentrum Kaiserslautern
SP  - 49
EP  - 53
PB  - Fraunhofer Verlag
CY  - Karlsruhe
ER  - 
TY  - GEN
A1  - Duwe, A.
A1  - Schlegel, C.
A1  - Tippkötter, Nils
A1  - Ulber, Roland
T1  - Sequentielle Extraktion von Cellulose zur effizienten Nutzung der Stoffströme in der Holzbioraffinerie
T2  - Chemie Ingenieur Technik
N2  - In der Reihe der nachwachsenden Rohstoffe besitzt Holz als erneuerbare und umweltfreundliche Ressource ein großes Potenzial. Über 11 Mio. ha Holz, das laut der Fachagentur für nachwachsende Rohstoffe (FNR) auch für industrielle Zwecke genutzt werden kann, wuchsen im Jahr 2013 allein auf bundesdeutscher Fläche. 56,8 Mio. m³ jährlicher Holzeinschlag in den letzten zehn Jahren wurde zu knapp der Hälfte stofflich und der Rest energetisch verwertet. Im Rahmen dieser Arbeit konnte auf der Basis vom Holz der Buche, die nach Fichte und Kiefer die dritthäufigste Baumart in Deutschland ist und 15% der deutschen Waldfläche ausmacht, die Fraktionierung der polymeren Hauptbestandteile mit niedrigem energetischen Einsatz erreicht werden. Hierbei werden in einem nachgeschalteten Extraktionsprozess die beiden Komponenten Hemicellulose und Lignin in flüssiger Form von der finalen festen Cellulosefraktion abgetrennt. Die Extraktion der Hemicellulose erfolgt durch eine Liquid Hot Water (LHW)-Behandlung. Untersucht wird der katalytische Zusatz anorganischer Säuren wie H₃PO₄ und H₂SO₄. Im Hinblick auf die weitere Verwertung von Lignin zu aromatischen Synthesebausteinen kommt die Organosolv-Extraktion mit einem Ethanol/Wasser-Gemisch zum Einsatz. Von Vorteil ist die weitere Verwendung beider Stoffströme ohne Fällungsschritt und nachteiliger Verdünnung der Hemicellulose.
Y1  - 2014
U6  - https://doi.org/10.1002/cite.201450308
SN  - 0009-286X
SN  - 1522-2640 (eISSN)
N1  - ProcessNet-Jahrestagung 2014 und 31. DECHEMA-Jahrestagung der Biotechnologen, 30. September - 2. Oktober 2014, Eurogress Aachen
VL  - 86
IS  - 9
SP  - 1400
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - GEN
A1  - Möhring, S.
A1  - Wulfhorst, H.
A1  - Capitain, C.
A1  - Roth, J.
A1  - Tippkötter, Nils
T1  - Fractioning of lignocellulosic biomass: Scale-down and automation of thermal pretreatment for parameter optimization
T2  - Chemie Ingenieur Technik
N2  - In order to efficiently convert lignocellulose, it is often necessary to conduct a pretreatment. The biomass considered in this study typically comprises of agricultural and horticultural residues, as well as beechwood. A very environmentally friendly method, namely, fungal pretreatment using white-rot fungi, leads to an enhanced enzymatic hydrolysis. In contrast to other processes presented, the energy input is extremely low. However, the fungal growth on the lignocellulosic substrates takes several weeks at least in order to be effective. Thus, the reduction of chemicals and energy for thermal processing is a target of our current research. Liquid hot water (LHW) and solvent-based pretreatment (OrganoSolv) require more complex equipment, as they depend on high temperatures (160 – 180 °C) and enhanced pressure (up to 20 bar). However, they prove to be promising processes in regard to the fractioning of lignocellulose. For optimal lignin recovery the parameters differ from those established in cellulose extraction. A novel screening system scaled down to a reaction volume of 100 mL has been developed and successfully tested for this purpose.
Y1  - 2016
U6  - https://doi.org/10.1002/cite.201650288
SN  - 0009-286X
SN  - 1522-2640 (eISSN)
N1  - ProcessNet-Jahrestagung und 32. DECHEMA-Jahrestagung der Biotechnologen 2016, 12. - 15. September 2016, Eurogress Aachen
VL  - 88
IS  - 9
SP  - 1229
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - GEN
A1  - Ross-Jones, J.
A1  - Teumer, T.
A1  - Capitain, C.
A1  - Tippkötter, Nils
A1  - Krause, M. J.
A1  - Methner, F.-J.
A1  - Rädle, M.
T1  - Analytical methods for in-line characterization of beer haze
T2  - Trends in Brewing
N2  - In most beers, producers strive to minimize haze to maximize visual appeal. To detect the formation of particulates, a measurement system for sub-micron particles is required. Beer haze is naturally occurring, composed of protein or polyphenol particles; in their early stage of growth their size is smaller than 2 µm. Microscopy analysis is time and resource intensive; alternatively, backscattering is an inexpensive option for detecting particle sizes of interest.
Y1  - 2018
N1  - Trends in Brewing, April 8 –12, 2018, Ghent, Belgium
ER  - 
TY  - GEN
A1  - Tippkötter, Nils
A1  - Ulber, Roland
T1  - Eine magnetische horizontale Wirbelschicht für die Durchmischung und Rückhaltung von magnetisierbaren Mikropartikeln im Durchfluss
T2  - Chemie Ingenieur Technik
N2  - Magnetisierbare Partikel als Träger von Katalysatoren können durch Anlegen eines magnetisches Feldes einfach und schnell abgetrennt werden. Die Wiedergewinnung von wertvollen Enzymen unter geringem Energie- und Materialeinsatz der magnetischen Abtrennung eröffnet einen Wettbewerbsvorteil für Produktionsprozesse. Die Abtrennung von magnetisierbaren Partikeln vom Überstand wird üblicherweise entweder durch Anlegen eines äußeren Magnetfelds und der resultierenden Ablagerung der Partikel an den Reaktorwänden oder durch Hochgradientenmagnetseparation (HGMS)durchgeführt. Beide Verfahren resultieren meist in der Bildung eines Filterkuchens aus Magnetpartikeln und den Feststoffen des Reaktionsmediums. Das magnetische horizontale Wirbelbett ermöglicht simultan eine kontinuierliche Reaktionsführung und die Rückhaltung der Partikel im Durchfluss. Die Partikelsuspension fließt durch einen Rohrreaktor, der in einem Magnetfeld mit wechselnden Feldgradienten eingebracht ist. Die Änderung des Magnetfeldgradienten erfolgt entgegen der Strömungsrichtung der Reaktionslösung. Durch alternierende Feldmaxima an den beiden Seiten des Reaktors werden die magnetisierbaren Partikel zu dessen Wänden gezogen. Bei Umkehrung des Feldes wandern die Partikel an die gegenüberliegende Reaktorwand. Durch Wahl einer geeigneten Wechselfrequenz kann eine kontinuierliche Durchmischung und Rückhaltung der Mikropartikel im durchströmten Rohr erreicht werden. Somit können Immobilisierungsreaktionen und Biotransformationen mit den Partikelsystemen im Durchfluss durchgeführt werden.
Y1  - 2009
U6  - https://doi.org/10.1002/cite.200950076
SN  - 0009-286X
SN  - 1522-2640 (eISSN)
N1  - ProcessNet‐Jahrestagung 2009 und 27. DECHEMA-Jahrestagung der Biotechnologen, 8.- 10. September 2009, Mannheim
VL  - 81
IS  - 8
SP  - 1168
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Hafidi, Youssef
A1  - El Hatka, Hicham
A1  - Schmitz, Dominik
A1  - Krauss, Manuel
A1  - Pettrak, Jürgen
A1  - Biel, Markus
A1  - Ittobane, Najim
T1  - Sustainable soil additives for water and micronutrient supply: swelling and chelating properties of polyaspartic acid hydrogels utilizing newly developed crosslinkers
JF  - Gels
N2  - Drought and water shortage are serious problems in many arid and semi-arid regions. This problem is getting worse and even continues in temperate climatic regions due to climate change. To address this problem, the use of biodegradable hydrogels is increasingly important for the application as water-retaining additives in soil. Furthermore, efficient (micro-)nutrient supply can be provided by the use of tailored hydrogels. Biodegradable polyaspartic acid (PASP) hydrogels with different available (1,6-hexamethylene diamine (HMD) and L-lysine (LYS)) and newly developed crosslinkers based on diesters of glycine (GLY) and (di-)ethylene glycol (DEG and EG, respectively) were synthesized and characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) and regarding their swelling properties (kinetic, absorbency under load (AUL)) as well as biodegradability of PASP hydrogel. Copper (II) and zinc (II), respectively, were loaded as micronutrients in two different approaches: in situ with crosslinking and subsequent loading of prepared hydrogels. The results showed successful syntheses of di-glycine-ester-based crosslinkers. Hydrogels with good water-absorbing properties were formed. Moreover, the developed crosslinking agents in combination with the specific reaction conditions resulted in higher water absorbency with increased crosslinker content used in synthesis (10% vs. 20%). The prepared hydrogels are candidates for water-storing soil additives due to the biodegradability of PASP, which is shown in an exemple. The incorporation of Cu(II) and Zn(II) ions can provide these micronutrients for plant growth.
KW  - micronutrients
KW  - swelling properties
KW  - biodegradable polymers
KW  - hydrogels
KW  - superabsorbent polymers
KW  - glycine
KW  - polyaspartic acid
Y1  - 2024
U6  - https://doi.org/10.3390/gels10030170
SN  - 2310-2861
VL  - 10
IS  - 3
SP  - Artikel 170
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Hoffstadt, Kevin
A1  - Nikolausz, Marcell
A1  - Krafft, Simone
A1  - Bonatelli, Maria
A1  - Kumar, Vivekanantha
A1  - Harms, Hauke
A1  - Kuperjans, Isabel
T1  - Optimization of the ex situ biomethanation of hydrogen and carbon dioxide in a novel meandering plug flow reactor: start-up phase and flexible operation
JF  - Bioengineering
KW  - methanation
KW  - plug flow reactor
KW  - bubble column
KW  - biomethane
KW  - P2G
Y1  - 2024
U6  - https://doi.org/10.3390/bioengineering11020165
SN  - 2306-5354
VL  - 11
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Adels, Klaudia
A1  - Monakhova, Yulia
T1  - Low-field NMR spectroscopic study of e-cigarettes: Is determination of only nicotine and organic carrier solvents possible?
JF  - Microchemical Journal
N2  - Electronic cigarettes (e-cigarettes) have become popular worldwide with the market growing exponentially in some countries. The absence of product standards and safety regulations requires urgent development of analytical methodologies for the holistic control of the growing diversity of such products. An approach based on low-field nuclear magnetic resonance (LF-NMR) at 80 MHz is presented for the simultaneous determination of key parameters: carrier solvents (vegetable glycerine (VG), propylene glycol (PG) and water), total nicotine as well as free-base nicotine fraction. Moreover, qualitative and quantitative determination of fourteen weak organic acids deliberately added to enhance sensory characteristics of e-cigarettes was possible. In most cases these parameters can be rapidly and conveniently determined without using any sample manipulation such as dilution, extraction or derivatization steps. The method was applied for 37 authentic e-cigarettes samples. In particular, eight different organic acids with the content up to 56 mg/mL were detected. Due to its simplicity, the method can be used in routine regulatory control as well as to study release behaviour of nicotine and other e-cigarettes constituents in different products.
KW  - Electronic cigarettes
KW  - Low field NMR
KW  - Carrier solvents
KW  - Free-base nicotine
KW  - Weak organic acids
Y1  - 2024
U6  - https://doi.org/10.1016/j.microc.2024.110859
SN  - 1095-9149
N1  - Corresponding author: Yulia Monakhova
VL  - 203
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Tix, Julian
A1  - Moll, Fabian
A1  - Krafft, Simone
A1  - Betsch, Matthias
A1  - Tippkötter, Nils
T1  - Hydrogen production from enzymatic pretreated organic waste with thermotoga neapolitana
JF  - Energies
N2  - Biomass from various types of organic waste was tested for possible use in hydrogen production. The composition consisted of lignified samples, green waste, and kitchen scraps such as fruit and vegetable peels and leftover food. For this purpose, the enzymatic pretreatment of organic waste with a combination of five different hydrolytic enzymes (cellulase, amylase, glucoamylase, pectinase and xylase) was investigated to determine its ability to produce hydrogen (H2) with the hydrolyzate produced here. In course, the anaerobic rod-shaped bacterium T. neapolitana was used for H2 production. First, the enzymes were investigated using different substrates in preliminary experiments. Subsequently, hydrolyses were carried out using different types of organic waste. In the hydrolysis carried out here for 48 h, an increase in glucose concentration of 481% was measured for waste loads containing starch, corresponding to a glucose concentration at the end of hydrolysis of 7.5 g·L−1. In the subsequent set fermentation in serum bottles, a H2 yield of 1.26 mmol H2 was obtained in the overhead space when Terrific Broth Medium with glucose and yeast extract (TBGY medium) was used. When hydrolyzed organic waste was used, even a H2 yield of 1.37 mmol could be achieved in the overhead space. In addition, a dedicated reactor system for the anaerobic fermentation of T. neapolitana to produce H2 was developed. The bioreactor developed here can ferment anaerobically with a very low loss of produced gas. Here, after 24 h, a hydrogen concentration of 83% could be measured in the overhead space.
KW  - Biological hydrogen
KW  - Organic waste
KW  - Dark fermentation
KW  - Hydrolysis
KW  - Pretreatment
Y1  - 2024
U6  - https://doi.org/10.3390/en17122938
SN  - 1996-1073
N1  - Corresponding author: Nils Tippkötter
VL  - 17
IS  - 12
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Tippkötter, Nils
A1  - Ulber, Roland
T1  - Rezension zu: Encyclopedia of Industrial Biotechnology, Vol. 1–7. By MC Flickinger.
JF  - Chemie Ingenieur Technik
Y1  - 2012
U6  - https://doi.org/10.1002/cite.201290052
SN  - 0009-286X
SN  - 1522-2640 (eISSN)
VL  - 6
IS  - 84
SP  - 936
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Oehlenschläger, Katharina
A1  - Volkmar, Marianne
A1  - Stiefelmaier, Judith
A1  - Langsdorf, Alexander
A1  - Holtmann, Dirk
A1  - Tippkötter, Nils
A1  - Ulber, Roland
T1  - New insights into the influence of pre-culture on robust solvent production of C. acetobutylicum
JF  - Applied Microbiology and Biotechnology
N2  - Clostridia are known for their solvent production, especially the production of butanol. Concerning the projected depletion of fossil fuels, this is of great interest. The cultivation of clostridia is known to be challenging, and it is difficult to achieve reproducible results and robust processes. However, existing publications usually concentrate on the cultivation conditions of the main culture. In this paper, the influence of cryo-conservation and pre-culture on growth and solvent production in the resulting main cultivation are examined. A protocol was developed that leads to reproducible cultivations of Clostridium acetobutylicum. Detailed investigation of the cell conservation in cryo-cultures ensured reliable cell growth in the pre-culture. Moreover, a reason for the acid crash in the main culture was found, based on the cultivation conditions of the pre-culture. The critical parameter to avoid the acid crash and accomplish the shift to the solventogenesis of clostridia is the metabolic phase in which the cells of the pre-culture were at the time of inoculation of the main culture; this depends on the cultivation time of the pre-culture. Using cells from the exponential growth phase to inoculate the main culture leads to an acid crash. To achieve the solventogenic phase with butanol production, the inoculum should consist of older cells which are in the stationary growth phase. Considering these parameters, which affect the entire cultivation process, reproducible results and reliable solvent production are ensured.
KW  - Pre-culture
KW  - Metabolic shift
KW  - Acid crash
KW  - C. acetobutylicum
KW  - ABE
KW  - Butanol
Y1  - 2024
U6  - https://doi.org/10.1007/s00253-023-12981-8
SN  - 1432-0614
VL  - 108
PB  - Springer
CY  - Berlin, Heidelberg
ER  - 
TY  - JOUR
A1  - Hengsbach, Jan-Niklas
A1  - Engel, Mareike
A1  - Cwienczek, Marcel
A1  - Stiefelmaier, Judith
A1  - Tippkötter, Nils
A1  - Ulber, Roland
T1  - Scalable unseparated bioelectrochemical reactors by using a carbon fiber brush as stirrer and working electrode
JF  - ChemElectroChem
N2  - The concept of energy conversion into platform chemicals using bioelectrochemical systems (BES) has gained increasing attention in recent years, as the technology simultaneously provides an opportunity for sustainable chemical production and tackles the challenge of Power-to-X technologies. There are many approaches to realize the industrial scale of BES. One concept is to equip standard bioreactors with static electrodes. However, large installations resulted in a negative influence on various reactor parameters. In this study, we present a new single-chamber BES based on a stirred tank reactor in which the stirrer was replaced by a carbon fiber brush, performing the functions of the working electrode and the stirrer. The reactor is characterized in abiotic studies and electro-fermentations with Clostridium acetobutylicum. Compared to standard reactors an increase in butanol production of 20.14±3.66 % shows that the new BES can be efficiently used for bioelectrochemical processes.
Y1  - 2023
U6  - https://doi.org/10.1002/celc.202300440
SN  - 2196-0216
VL  - 10
IS  - 21
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - GEN
A1  - Roth, J.
A1  - Tippkötter, Nils
T1  - New Approach for Enzymatic Hydrolysis of Lignocellulose with Selective Diffusion Separation of the Monosaccharide Products
T2  - Chemie Ingenieur Technik
N2  - Enzymatic hydrolysis of lignocellulosic material plays an important role in the classical biorefinery approach. Apart from the pretreatment of the raw material, hydrolysis is the basis for the conversion of the cellulose and hemicellulose fraction into fermentable sugars. After hydrolysis, usually a solid-liquid separation takes place, in order to separate the residual plant material from the sugar-rich fraction, which can be subsequently used in a fermentation step. In order to factor out the separation step, the usage of in alginate immobilized crude cellulose fiber beads (CFBs) were evaluated. Pretreated cellulose fibers are incorporated in an alginate matrix together with the relevant enzymes. In doing so, sugars diffuse trough the alginate matrix, allowing a simplified delivery into the surrounding fluid. This again reduces product inhibition of the glucose on the enzyme catalysts. By means of standardized bead production the hydrolysis in lab scale was possible. First results show that liberation of glucose and xylose is possible, allowing a maximum total sugar yield of 75 %.
Y1  - 2016
U6  - https://doi.org/10.1002/cite.201650301
SN  - 0009-286X
SN  - 1522-2640 (eISSN)
N1  - ProcessNet-Jahrestagung 2016 und 32. DECHEMA-Jahrestagung der Biotechnologen 2016, 12. - 15. September 2016, Eurogress Aachen
VL  - 88
IS  - 9
SP  - 1237
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Mues genannt Koers, Lucas
A1  - McNeil, S. W.
A1  - Radchenko, V.
A1  - Paulßen, Elisabeth
A1  - Hoehr, Cornelia
T1  - Production of Co-58m in a siphon-style liquid target on a medical cyclotron
N2  - We present the production of 58mCo on a small, 13 MeV medical cyclotron utilizing a siphon style liquid target system. Different concentrated iron(III)-nitrate solutions of natural isotopic distribution were irradiated at varying initial pressures and subsequently separated by solid phase extraction chromatography. The radio cobalt (58m/gCo and 56Co) was successfully produced with saturation activities of (0.35 ± 0.03) MBq μA−1 for 58mCo with a separation recovery of (75 ± 2) % of cobalt after one separation step utilizing LN-resin.
Y1  - 2023
U6  - https://doi.org/10.1016/j.apradiso.2023.110734
SN  - 0969-8043
VL  - 195
IS  - Art. 110734
PB  - Elsevier
CY  - Amsterdam
ER  -