112 research outputs found
Procede pour produire des acides l-amines par fermentation au moyen de bacteries coryneformes
No full textWendisch VF, Rittmann D, Sahm H, Kreutzer C. Procede pour produire des acides l-amines par fermentation au moyen de bacteries coryneformes. 02.08.2007
Method for the Fermentative Production of L-Amino Acids With the Aid of Coryneform Bacteria Capable of Using Glycerin as the Only Carbon Source
No full textWendisch VF, Rittmann D, Sahm H, Kreutzer C. Method for the Fermentative Production of L-Amino Acids With the Aid of Coryneform Bacteria Capable of Using Glycerin as the Only Carbon Source. 27.11.2008
Crude glycerol-based production of amino acids and putrescine by Corynebacterium glutamicum
No full textMeiswinkel T, Rittmann D, Lindner S, Wendisch VF. Crude glycerol-based production of amino acids and putrescine by Corynebacterium glutamicum. Bioresource Technology. 2013;145:254-258
Phosphate starvation-inducible gene ushA encodes a 5 ' nucleotidase required for growth of Corynebacterium glutamicum on media with nucleotides as the phosphorus source
No full textRittmann D, Sorger-Herrmann U, Wendisch VF. Phosphate starvation-inducible gene ushA encodes a 5 ' nucleotidase required for growth of Corynebacterium glutamicum on media with nucleotides as the phosphorus source. Applied and Environmental Microbiology. 2005;71(8):4339-4344.Phosphorus is an essential component of macromolecules, like DNA, and central metabolic intermediates, such as sugar phosphates, and bacteria possess enzymes and control mechanisms that provide an optimal supply of phosphorus from the environment. UDP-sugar hydrolases and 5' nucleotidases may play roles in signal transduction, as they do in mammals, in nucleotide salvage, as demonstrated for UshA of Escherichia coli, or in phosphorus metabolism. The Corynebacterium glutamicum gene ushA was found to encode a secreted enzyme which is active as a 5' nucleotidase and a UDP-sugar hydrolase. This enzyme was synthesized and secreted into the medium when C. glutamicum was starved for inorganic phosphate. UshA was required for growth of C. glutamicum on AMP and UDP-glucose as sole sources of phosphorus. Thus, in contrast to UshA from E. coli, C. glutamicum UshA is an important component of the phosphate starvation response of this species and is necessary to access nucleotides and related compounds as sources of phosphorus
Substrate interactions during the anaerobic biodegradation of 1,1,1-trichloroethane
No full textHalogenated aliphatic hydrocarbons are used in large amounts, persist when released into the environment, and can have adverse effects on human health. Reductive dehalogenation, in which cleavage of carbon-halogen bonds is accompanied by electron transfer to the halogenated substrate, is the most important mechanism for the anaerobic biodegradation of highly halogenated aliphatic hydrocarbons. The concentrations of primary electron-donor and -acceptor substrates, which control the intracellular availability of electrons, can affect the rates of these reactions. A mechanism-based model that describes the effects of the concentrations of primary electron donors and acceptors on the kinetics of reductive dehalogenation was developed and tested in anaerobic biofilm reactors. 1,1,1-trichloroethane (TCA) was used as a model halogenated substrate. The model is based on the assumption that the rate of reductive dehalogenation is controlled by the intracellular concentration of a reduced metalloenzyme (the dehalogenase). The concentration of the reduced dehalogenase is controlled by the external concentrations of the electron donor and acceptor. Although Monod kinetics adequately described the relationship between TCA concentration and its biodegradation rate, the Monod kinetic parameters were functions of the concentrations of the primary electron donor and acceptor. The apparent maximum specific rate of TCA biodegration, q\sb{\rm m,ap}, and the apparent half-saturation concentration, K\sb{\rm ap}, increased as the concentration of the electron-donor substrate increased. The primary electron-acceptor substrate slowed the first-order rate of TCA biodegradation, because it caused K\sb{\rm ap} to increase without affecting q\sb{\rm m,ap}. These results provide a quantitative and mechanistically based tool for understanding and controlling the rates of reductive dehalogenation in treatment reactors and in situ bioremediations.Made available in DSpace on 2011-05-07T13:29:32Z (GMT). No. of bitstreams: 2
license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5)
9215909.pdf: 11112825 bytes, checksum: 2d9633dc7cf65cf0609754891c3931ba (MD5)
Previous issue date: 1992Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:55:27Z
Item is restricted indefinitely.Restriction data tranferred 2014-07-01T11:25:50-05:00
Original Data
Group with Access UIUC Users [automated]
Release Date: none
Reason: ETDs are only available to UIUC Users without author permissionETDs are only available to UIUC Users without author permissionU of I Onl
Modeling dual-limitation kinetics incorporating intracellular cofactor responses
No full textIntracellular cofactors--such as NADH, NAD, ATP, ADP, and P\sb{\rm i}--are important co-substrates that can affect the rate of the cell's catabolic and respiratory reactions. Pure-culture experiments with Pseudomonas putida P\sb{\rm p}F1 performed in a special chemostat apparatus, using acetate as electron donor and O\sb2 as electron acceptor, revealed that the cofactor concentrations vary highly systematically with changes in availability of the external electron donor and acceptor. In general, the NAD/NADH ratio increased as the DO concentration rose or the acetate concentration fell, while the ATP/ADPP\sb{\rm i} value increased as the electron-donor utilization rate decreased.A structured model for substrate-utilization kinetics under simultaneous limitation of electron donor and acceptor (i.e., dual-limitation) was developed by incorporating those cofactor ratios as variables. The model, which described the observed electron-donor utilization rate satisfactorily under dual- and single-limited conditions, demonstrated that the systematic responses with the NAD/NADH ratio accelerate the limiting reaction (e.g., catabolic reaction) at the cost of slowing the nonlimiting reaction (e.g., respiration), maximizing the overall growth rate under a given dual-limitation condition. Linkage of the systematic internal responses to external primary electron-donor and acceptor concentrations transformed the structured model into a double-Monod model; thus, the co-limitation by both substrates reduced the overall reaction rate multiplicatively.The systematic changes in the cellular NAD(H) concentrations could be applied to biodegradation of halogenated or nonhalogenated hydrocarbons whose degradation requires reducing power. A secondary-substrate utilization model predicted a maximum reductive dehalogenation at a saturating concentration of electron donor. The % removal, however, was very sensitive to substrate-concentration changes for the combination of high electron-acceptor and low electron-donor concentrations--a very common situation in biological treatment processes. For nonhalogenated hydrocarbons that are degraded by mono or dioxygenase reactions, consistently high % removals could be achieved when the concentrations of primary electron donor and acceptor are high together. Since the oxygen concentration, in addition to the reducing power, controls the oxygenase reaction, no satisfactory removal could be expected when either concentration was low.Made available in DSpace on 2011-05-07T13:28:03Z (GMT). No. of bitstreams: 2
license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5)
9236394.pdf: 7669297 bytes, checksum: 94d5e97a455d886559dc45ba0eae0fa9 (MD5)
Previous issue date: 1992Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:55:08Z
Item is restricted indefinitely.Restriction data tranferred 2014-07-01T11:25:40-05:00
Original Data
Group with Access UIUC Users [automated]
Release Date: none
Reason: ETDs are only available to UIUC Users without author permissionETDs are only available to UIUC Users without author permissionU of I Onl
Quantification of interactions between inhibitory primary and secondary substrates
No full textItem marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:51:00Z
Item is restricted indefinitely.The kinetic effects of the presence of one substrate on the degradation rate of the other substrate in a single-species, bisubstrate system were quantified in detail. The system consisted of a pure culture (Pseudomonas putida P\sb{\rm p}G4 (ATCC 17453)) transforming phenol and 4-chlorophenol simultaneously under fully aerobic conditions.Phenol behaved as a self-inhibitory primary substrate, whose biodegradation rate when present as a single substrate could be modeled well using Haldane Kinetics. 4-chlorophenol behaved as a co-metabolite, because its transformation, observed at a significant rate, did not yield any increases in biomass.When phenol and 4-chlorophenol were present together, the 4-chlorophenol- transformation rate was proportional to the phenol-oxidation rate, because the electrons required for the transformation of 4-chlorophenol were provided by the oxidation of phenol. In the absence of phenol, the 4-chlorophenol-transformation rate was proportional to the biomass-decay rate, because the required electrons were then provided by the biomass oxidation. These proportionalities in the rates clearly indicated that 4-chlorophenol transformation was possible only in the presence of a source of electrons, such as phenol or biomass.4-chlorophenol inhibited phenol biodegradation. Two types of inhibitory effects were observed. For experiments with low initial 4-chlorophenol/phenol (I/S) ratios, the inhibition mainly decreased the Haldane qm\sb{\rm s} parameter. On the other hand, the inhibition for high initial I/S ratios mainly was expressed by an increase to the Haldane K\sb{\rm s} parameter for phenol. Similarly to the 4-chlorophenol-alone systems, the controlling variable for the type of inhibition observed in the bisubstrate system was the 4-chlorophenol/biomass ratio at the time when phenol oxidation stopped.In summary, phenol was absolutely required for the transformation of 4-chlorophenol, because this transformation required electrons for regenerating the NADPH consumed. The requirement for phenol can be direct, manifested in the actual presence of phenol, or indirect, manifested in the cell mass grown previously when phenol was present (the cells acted as an electron reservoir in this case). 4-chlorophenol, in turn, was inhibitory to the degradation of phenol and to its own transformation.Made available in DSpace on 2011-05-07T13:09:34Z (GMT). No. of bitstreams: 2
license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5)
9114397.pdf: 8194223 bytes, checksum: 4e95b2a3a4dc5dd8c70d2f422d171268 (MD5)
Previous issue date: 1990Restriction data tranferred 2014-07-01T11:23:22-05:00
Original Data
Group with Access UIUC Users [automated]
Release Date: none
Reason: ETDs are only available to UIUC Users without author permissionETDs are only available to UIUC Users without author permissionU of I Onl
A Combined Activated Sludge Anaerobic Digestion Model (CASADM) to understand the role of anaerobic sludge recycling in wastewater treatment plant performance
No full textabstract: The Combined Activated Sludge-Anaerobic Digestion Model (CASADM) quantifies the effects of recycling anaerobic-digester (AD) sludge on the performance of a hybrid activated sludge (AS)-AD system. The model includes nitrification, denitrification, hydrolysis, fermentation, methanogenesis, and production/utilization of soluble microbial products and extracellular polymeric substances (EPS). A CASADM example shows that, while effluent COD and N are not changed much by hybrid operation, the hybrid system gives increased methane production in the AD and decreased sludge wasting, both caused mainly by a negative actual solids retention time in the hybrid AD. Increased retention of biomass and EPS allows for more hydrolysis and conversion to methane in the hybrid AD. However, fermenters and methanogens survive in the AS, allowing significant methane production in the settler and thickener of both systems, and AD sludge recycle makes methane formation greater in the hybrid system.“NOTICE: this is the author’s version of a work that was accepted for publication in Bioresource Technology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Bioresource Technology, 136, 196-204. doi:10.1016/j.biortech.2013.02.090
Nitrite Accumulation From Simultaneous Free-Ammonia and Free-Nitrous-Acid Inhibition and Oxygen Limitation in a Continuous-Flow Biofilm Reactor
No full textabstract: To achieve nitrite accumulation for shortcut biological nitrogen removal (SBNR) in a biofilm process, we explored the simultaneous effects of oxygen limitation and free ammonia (FA) and free nitrous acid (FNA) inhibition in the nitrifying biofilm. We used the multi-species nitrifying biofilm model (MSNBM) to identify conditions that should or should not lead to nitrite accumulation, and evaluated the effectiveness of those conditions with experiments in continuous flow biofilm reactors (CFBRs). CFBR experiments were organized into four sets with these expected outcomes based on the MSNBM as follows: (i) Control, giving full nitrification; (ii) oxygen limitation, giving modest long-term nitrite build up; (iii) FA inhibition, giving no long-term nitrite accumulation; and (iv) FA inhibition plus oxygen limitation, giving major long-term nitrite accumulation. Consistent with MSNBM predictions, the experimental results showed that nitrite accumulated in sets 2–4 in the short term, but long-term nitrite accumulation was maintained only in sets 2 and 4, which involved oxygen limitation. Furthermore, nitrite accumulation was substantially greater in set 4, which also included FA inhibition. However, FA inhibition (and accompanying FNA inhibition) alone in set 3 did not maintained long-term nitrite accumulation. Nitrite-oxidizing bacteria (NOB) activity batch tests confirmed that little NOB or only a small fraction of NOB were present in the biofilms for sets 4 and 2, respectively. The experimental data supported the previous modeling results that nitrite accumulation could be achieved with a lower ammonium concentration than had been required for a suspended-growth process. Additional findings were that the biofilm exposed to low dissolved oxygen (DO) limitation and FA inhibition was substantially denser and probably had a lower detachment rate.This is the peer reviewed version of the article, which has been published in final form at http://dx.doi.org/10.1002/bit.2532
Improving lipid recovery from Scenedesmus wet biomass by surfactant-assisted disruption
No full textabstract: Microalgae-derived lipids are good sources of biofuel, but extracting them involves high cost, energy
expenditure, and environmental risk. Surfactant treatment to disrupt Scenedesmus biomass was evaluated
as a means to make solvent extraction more efficient. Surfactant treatment increased the recovery of fatty
acid methyl ester (FAME) by as much as 16-fold vs. untreated biomass using isopropanol extraction, and
nearly 100% FAME recovery was possible without any Folch solvent, which is toxic and expensive. Surfactant
treatment caused cell disruption and morphological changes to the cell membrane, as documented by
transmission electron microscopy and flow cytometry. Surfactant treatment made it possible to extract wet
biomass at room temperature, which avoids the expense and energy cost associated with heating
and drying of biomass during the extraction process. The best FAME recovery was obtained from highlipid
biomass treated with Myristyltrimethylammonium bromide (MTAB)- and 3-(decyldimethylammonio)-
propanesulfonate inner salt (3_DAPS)-surfactants using a mixed solvent (hexane : isopropanol = 1 : 1, v/v)
vortexed for just 1 min; this was as much as 160-fold higher than untreated biomass. The critical micelle
concentration of the surfactants played a major role in dictating extraction performance, but the growth
stage of the biomass had an even larger impact on how well the surfactants disrupted the cells and
improved lipid extraction. Surfactant treatment had minimal impact on extracted-FAME profiles and,
consequently, fuel-feedstock quality. This work shows that surfactant treatment is a promising strategy for
more efficient, sustainable, and economical extraction of fuel feedstock from microalgae.The supporting information contains 6 pages, including Table S1 for the character of different growth type of biomass, Fig S1 for the quantity of FAME under the two
different solvents, Fig S2 FAME profile via Folch and isopropanol extraction under different surfactant treatments, Fig S3 Cell structures of protein-rich Scenedesmus biomass under 3_DAPS, MTMA and SDS treatments, Fig S4 Cell structures of intermediate-lipid Scenedesmus biomass under 3_DAPS, MTMA and SDS treatments, and Fig S5 for the flow cytometer assay with SYTOX green emission.View the article on the journal page at http://pubs.rsc.org/en/content/articlelanding/2015/gc/c5gc02159
- …
