共查询到20条相似文献,搜索用时 31 毫秒
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Cees Haringa 《Engineering in Life Science》2023,23(1):e2100159
Euler-Lagrange CFD simulations, where the biotic phase is represented by computational particles (parcels), provide information on environmental gradients inside bioreactors from the microbial perspective. Such information is highly relevant for reactor scale-down and process optimization. One of the major challenges is the computational intensity of CFD simulations, especially when resolution of dynamics in the flowfield is required. Lattice-Boltzmann large-eddy simulations (LB-LES) form a very promising approach for simulating accurate, dynamic flowfields in stirred reactors, at strongly reduced computation times compared to finite volume approaches. In this work, the performance of LB-LES in resolving substrate gradients in large-scale bioreactors is explored, combined with the inclusion of a Lagrangian biotic phase to provide the microbial perspective. In addition, the hydrodynamic performance of the simulations is confirmed by verification of hydrodynamic characteristics (radial velocity, turbulent kinetic energy, energy dissipation) in the impeller discharge stream of a 29 cm diameter stirred tank. The results are compared with prior finite volume simulation results, both in terms of hydrodynamic and biokinetic observations, and time requirements. 相似文献
3.
Erick J. Vandamme 《Enzyme and microbial technology》1983,5(6):403-416
The use of immobilized biocatalysts for producing known or new antibiotics is presented. An evaluation of the applicability of this concept in the fascinating field of peptide antibiotic bioconversions and fermentations is also given.The use of immobilized enzymes, organelles and cells to synthesize antibiotics as an alternative method to conventional fermentation is discussed. In vitro total enzymatic antibiotic synthesis is illustrated with the ‘multienzyme thiotemplate mechanism’ of Bacillus brevis, the producer of gramicidin S. Total synthesis of peptide antibiotics, based on immobilized living cells, has recently been demonstrated with penicillin, bacitracin, nisin and a few other antibiotics.As an industrial example of the use of enzymes or cells to convert peptide antibiotics into therapeutically useful derivatives, free and immobilized penicillin acylases, producing the penicillin nucleus 6-aminopenicillanic acid (6-APA), are reviewed as well as their potential to synthesize semisynthetic β-lactams (penicillins, cephalosporins).Acylases, acetylesterases and α-amino acid ester hydrolases acting on cephalosporin-compounds and yielding valuable intermediary or end products have also gained wide interest. Stereospecific enzymic side-chain preparations for semisynthetic penicillin and cephalosporin production have recently reached the industrial stage. Bioconversion possibilities with the novel β-lactam compounds are suggested.These examples of simple single-step, as well as complex multi-step, enzyme reactions point to the vast potential of immobilized biocatalyst technology in fermentation science, in organic synthesis and in biotechnological processes in general. 相似文献
4.
Huseyin Balci Merve Tuzlakoglu Ozturk Tjaard Pijning Saliha Issever Ozturk Fusun Gumusel 《Applied microbiology and biotechnology》2014,98(10):4467-4477
Penicillin G acylase is the key enzyme used in the industrial production of β-lactam antibiotics. This enzyme hydrolyzes penicillin G and related β-lactam antibiotics releasing 6-aminopenicillanic acid, which is an intermediate in the production of semisynthetic penicillins. To improve the enzymatic activity of Escherichia coli penicillin acylase, sequential rounds of error-prone polymerase chain reaction were applied to the E. coli pac gene. After the second round of evolution, the best mutant M2234 with enhanced activity was selected and analyzed. DNA sequence analyses of M2234 revealed that one amino acid residue (K297I), located far from the center of the catalytic pocket, was changed. This mutant (M2234) has a specific activity 4.0 times higher than the parent enzyme and also displayed higher stability at pH 10. 相似文献
5.
Annick Lejeune F. Delvigne P. Thonart 《Journal of industrial microbiology & biotechnology》2010,37(3):225-236
Yeast is a widely used microorganism at the industrial level because of its biomass and metabolite production capabilities.
However, due to its sensitivity to the glucose effect, problems occur during scale-up to the industrial scale. Hydrodynamic
conditions are not ideal in large-scale bioreactors, and glucose concentration gradients can arise when these bioreactors
are operating in fed-batch mode. We have studied the effects of such gradients in a scale-down reactor, which consists of
a mixed part linked to a non-mixed part by a recirculation pump, in order to mimic the hydrodynamic conditions encountered
at the large scale. During the fermentation tests in the scale-down reactor, there was a drop in both biomass yield (ratio
between the biomass produced and the glucose added) and trehalose production and an increase in both fermentation time (time
between inoculation and beginning of stationary phase) and ethanol production. We have developed a stochastic model which
explains these effects as the result of an induction process determined mainly by the hydrodynamic conditions. The concentration
profiles experienced by the microorganisms during the scale-down tests were expressed and linked to the biomass yields of
the scale-down tests. 相似文献
6.
Hooff GP van Kampen JJ Meesters RJ van Belkum A Goessens WH Luider TM 《Journal of proteome research》2012,11(1):79-84
Plasmid-encoded β-lactamases are a major reason for antibiotic resistance in gram negative bacteria. These enzymes hydrolyze the β-lactam ring structure of certain β-lactam antibiotics, consequently leading to their inactivation. The clinical situation demands for specific first-line antibiotic therapy combined with a quick identification of bacterial strains and their antimicrobial susceptibility. Strategies for the identification of β-lactamase activity are often cumbersome and usually lack sensitivity and specificity. The current work demonstrates that matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) is an ideal tool for these analytical investigations. Herein, we describe a fast and specific assay to determine β-lactamase activity in bacterial lysates. The feasibility of the analytical read-out was demonstrated on a MALDI-triple quadrupole (QqQ) and a MALDI time-of-flight (TOF) instrument, and the results allow the comparison of both approaches. The assay specifically measures enzyme-mediated, time-dependent hydrolysis of the β-lactam ring structure of penicillin G and ampicillin and inhibition of hydrolysis by clavulanic acid for clavulanic acid susceptible β-lactamases. The assay is reproducible and builds the basis for future in-depth investigations of β-lactamase activity in various bacterial strains by mass spectrometry. 相似文献
7.
Boychyn M Yim SS Bulmer M More J Bracewell DG Hoare M 《Bioprocess and biosystems engineering》2004,26(6):385-391
Computational fluid dynamics was used to model the high flow forces found in the feed zone of a multichamber-bowl centrifuge and reproduce these in a small, high-speed rotating disc device. Linking the device to scale-down centrifugation, permitted good estimation of the performance of various continuous-flow centrifuges (disc stack, multichamber bowl, CARR Powerfuge) for shear-sensitive protein precipitates. Critically, the ultra scale-down centrifugation process proved to be a much more accurate predictor of production multichamber-bowl performance than was the pilot centrifuge. 相似文献
8.
Stefan S. Weber Andriy Kovalchuk Roel A.L. Bovenberg Arnold J.M. Driessen 《Fungal genetics and biology : FG & B》2012,49(11):915-921
The filamentous fungus Penicillium chrysogenum is used for the industrial production of β-lactam antibiotics. The pathway for β-lactam biosynthesis has been resolved and involves the enzyme phenylacetic acid CoA ligase that is responsible for the CoA activation of the side chain precursor phenylacetic acid (PAA) that is used for the biosynthesis of penicillin G. To identify ABC transporters related to β-lactam biosynthesis, we analyzed the expression of all 48 ABC transporters present in the genome of P. chryso-genum when grown in the presence and absence of PAA. ABC40 is significantly upregulated when cells are grown or exposed to high levels of PAA. Although deletion of this transporter did not affect β-lactam biosynthesis, it resulted in a significant increase in sensitivity to PAA and other weak acids. It is concluded that ABC40 is involved in weak acid detoxification in P. chrysogenum including resistance to phenylacetic acid. 相似文献
9.
An agent-based model of bacteria-antibiotic interactions has been developed that incorporates the antibiotic-resistance mechanisms of Methicillin-Resistant Staphylococcus aureus (MRSA). The model, called the Micro-Gen Bacterial Simulator, uses information about the cell biology of bacteria to produce global information about population growth in different environmental conditions. It facilitates a detailed systems-level investigation of the dynamics involved in bacteria-antibiotic interactions and a means to relate this information to traditional high-level properties such as the Minimum Inhibitory Concentration (MIC) of an antibiotic. The two main resistance strategies against β-lactam antibiotics employed by MRSA were incorporated into the model: β-lactamase enzymes, which hydrolytically cleave antibiotic molecules, and penicillin-binding proteins (PBP2a) with reduced binding affinities for antibiotics. Initial tests with three common antibiotics (penicillin, ampicillin and cephalothin) indicate that the model can be used to generate quantitatively accurate predictions of MICs for antibiotics against different strains of MRSA from basic cellular and biochemical information. Furthermore, by varying key parameters in the model, the relative impact of different kinetic parameters associated with the two resistance mechanisms to β-lactam antibiotics on cell survival in the presence of antibiotics was investigated. 相似文献
10.
de Jonge LP Buijs NA ten Pierick A Deshmukh A Zhao Z Kiel JA Heijnen JJ van Gulik WM 《Biotechnology journal》2011,6(8):944-958
In large-scale production reactors the combination of high broth viscosity and large broth volume leads to insufficient liquid-phase mixing, resulting in gradients in, for example, the concentrations of substrate and oxygen. This often leads to differences in productivity of the full-scale process compared with laboratory scale. In this scale-down study of penicillin production, the influence of substrate gradients on process performance and cell physiology was investigated by imposing an intermittent feeding regime on a laboratory-scale culture of a high yielding strain of Penicillium chrysogenum. It was found that penicillin production was reduced by a factor of two in the intermittently fed cultures relative to constant feed cultivations fed with the same amount of glucose per hour, while the biomass yield was the same. Measurement of the levels of the intermediates of the penicillin biosynthesis pathway, along with the enzyme levels, suggested that the reduction of the flux through the penicillin pathway is mainly the result of a lower influx into the pathway, possibly due to inhibitory levels of adenosine monophosphate and pyrophosphate and lower activating levels of adenosine triphosphate during the zero-substrate phase of each cycle of intermittent feeding. 相似文献
11.
Helena Marešová Martina Plačková Michal Grulich Pavel Kyslík 《Applied microbiology and biotechnology》2014,98(7):2867-2879
In the course of more than 60-year history, penicillin G acylase (PGA) gained a unique position among enzymes used by pharmaceutical industry for production of β-lactam antibiotics. Kinetically controlled enzymatic syntheses of cephalosporins of novel generations in which PGA catalyzes coupling of activated acyl donor with nucleophile belong among the latest large-scale applications. Contrary to rather specific roles of other enzymes involved in β-lactam biocatalyses, the PGA seems to have the greatest potential. On the laboratory scale, other applications with industrial potential were described, e.g., directed evolution of the enzyme to meet specific demands of industrial processes or its modification into the enzyme catalyzing reactions with novel substrates. The fact that β-lactams represent the most important group of antibiotics comprising 65 % of the world antibiotic market explains such a tremendous and continuous interest in this enzyme. Indeed, the annual consumption of PGA has recently been estimated to range from 10 to 30 million tons. The application potential of the enzyme goes beyond the β-lactam biocatalysis due to its enantioselectivity and promiscuity: the PGA can be used for the production of achiral and chiral compounds convenient for the preparation of synthons and active pharmaceutical ingrediences, respectively. These biocatalyses, however, still wait for large-scale application. 相似文献
12.
Schmidt FR 《Applied microbiology and biotechnology》2005,68(4):425-435
To increase product yields and to ensure consistent product quality, key issues of industrial fermentations, process optimization
and scale up are aimed at maintaining optimum and homogenous reaction conditions minimizing microbial stress exposure and
enhancing metabolic accuracy. For each individual product, process and facility, suitable strategies have to be elaborated
by a comprehensive and detailed process characterization, identification of the most relevant process parameters influencing
product yield and quality and their establishment as scale-up parameters to be kept constant as far as possible. Physical
variables, which can only be restrictedly kept constant as single parameters, may be combined with other pertinent parameters
to appropriate mathematical groups or dimensionless terms. Process characterization is preferably based on real-time or near
real-time data collected by in situ and on-line measurements and may be facilitated by supportive approaches and tools like
neural network based chemometric data analysis and modelling, clarification of the mixing and stream conditions through computational
fluid dynamics and scale-down simulations. However, as fermentation facilities usually are not strictly designed according
to scale-up criteria and the process conditions in the culture vessels thus may differ significantly and since any strategy
and model can only insufficiently consider and reflect the highly complex interdependence and mutual interaction of fermentation
parameters, successful scale up in most cases is not the result of a conclusive and straight-lined experimental strategy,
but rather will be the outcome of a separate process development and optimization on each scale. This article gives an overview
on the problems typically coming along with fermentation process optimization and scale up, and presents currently applied
scale-up strategies while considering future technologies, with emphasis on Escherichia coli as one of the most commonly fermented organisms. 相似文献
13.
Saul L. Neidleman 《Biotechnology & genetic engineering reviews》2013,29(1):1-38
β-lactam antibiotics (e.g. penicillins, cephalosporins) are of major clinical importance and contribute to over 40% of the total antibiotic market. These compounds are produced as secondary metabolites by certain actinomycetes and filamentous fungi (e.g. Penicillium, Aspergillus and Acremonium species). The industrial producer of penicillin is the fungus Penicillium chrysogenum. The enzymes of the penicillin biosynthetic pathway are well characterized and most of them are encoded by genes that are organized in a cluster in the genome. Remarkably, the penicillin biosynthetic pathway is compartmentalized: the initial steps of penicillin biosynthesis are catalyzed by cytosolic enzymes, whereas the two final steps involve peroxisomal enzymes. Here, we describe the biochemical properties of the enzymes of β-lactam biosynthesis in P. chrysogenum and the role of peroxisomes in this process. An overview is given 相似文献
14.
Antibiotic production through fermentation is often cited as an example of an established biotechnology. Yet despite the commercial importance of antibiotics, or perhaps because of it, there only exists in the public domain a relatively sketchy picture of the biochemistry and molecular genetics of producer strains.This article describes the metabolic pathways leading to β-lactam compounds and suggests strategies which could be adopted to improve productivity through molecular biology. 相似文献
15.
Kajan Srirangan Valerie Orr Lamees Akawi Adam Westbrook Murray Moo-Young C. Perry Chou 《Biotechnology advances》2013
In light of unrestricted use of first-generation penicillins, these antibiotics are now superseded by their semisynthetic counterparts for augmented antibiosis. Traditional penicillin chemistry involves the use of hazardous chemicals and harsh reaction conditions for the production of semisynthetic derivatives and, therefore, is being displaced by the biosynthetic platform using enzymatic transformations. Penicillin G acylase (PGA) is one of the most relevant and widely used biocatalysts for the industrial production of β-lactam semisynthetic antibiotics. Accordingly, considerable genetic and biochemical engineering strategies have been devoted towards PGA applications. This article provides a state-of-the-art review in recent biotechnological advances associated with PGA, particularly in the production technologies with an emphasis on using the Escherichia coli expression platform. 相似文献
16.
Acinetobacter baumannii, one of the major Gram negative bacteria, causes nosocomial infections such as pneumonia, urinary tract infection, meningitis, etc. β-lactam-based antibiotics like penicillin are used conventionally to treat infections of A. baumannii; however, they are becoming progressively less effective as the bacterium produces diverse types of β-lactamases to inactivate the antibiotics. We have recently identified a novel β-lactamase, OXA-51 from clinical strains of A. baumannii from our hospital. In the present study, we generated the structure of OXA-51 using MODELLER9v7 and studied the interaction of OXA-51 with a number of β-lactams (penicillin, oxacillin, ceftazidime, aztreonam and imipenem) using two independent programs: GLIDE and GOLD. Based on the results of different binding parameters and number of hydrogen bonds, interaction of OXA-51 was found to be maximum with ceftazidime and lowest with imipenem. Further, molecular dynamics simulation results also support this fact. The lowest binding affinity of imipenem to OXA-51 indicates clearly that it is not efficiently cleaved by OXA-51, thus explaining its high potency against resistant A. baumannii. This finding is supported by experimental results from minimum inhibitory concentration analysis and transmission electron microscopy. It can be concluded that carbapenems (imipenem) are presently effective β-lactam antibiotics against resistant strains of A. baumannii harbouring OXA-51. The results presented here could be useful in designing more effective derivatives of carbapenem. 相似文献
17.
Robert Spann Jens Glibstrup Klaus Pellicer-Alborch Stefan Junne Peter Neubauer Christophe Roca David Kold Anna Eliasson Lantz Gürkan Sin Krist V. Gernaey Ulrich Krühne 《Biotechnology and bioengineering》2019,116(4):769-780
The formation of pH gradients in a 700 L batch fermentation of Streptococcus thermophilus was studied using multi-position pH measurements and computational fluid dynamics (CFD) modeling. To this end, a dynamic, kinetic model of S. thermophilus and a pH correlation were integrated into a validated one-phase CFD model, and a dynamic CFD simulation was performed. First, the fluid dynamics of the CFD model were validated with NaOH tracer pulse mixing experiments. Mixing experiments and simulations were performed whereas multiple pH sensors, which were placed vertically at different locations in the bioreactor, captured the response. A mixing time of about 46 s to reach 95% homogeneity was measured and predicted at an impeller speed of 242 rpm. The CFD simulation of the S. thermophilus fermentation captured the experimentally observed pH gradients between a pH of 5.9 and 6.3, which occurred during the exponential growth phase. A pH higher than 7 was predicted in the vicinity of the base solution inlet. Biomass growth, lactic acid production, and substrate consumption matched the experimental observations. Moreover, the biokinetic results obtained from the CFD simulation were similar to a single-compartment simulation, for which a homogeneous distribution of the pH was assumed. This indicates no influence of pH gradients on growth in the studied bioreactor. This study verified that the pH gradients during a fermentation in the pilot-scale bioreactor could be accurately predicted using a coupled simulation of a biokinetic and a CFD model. To support the understanding and optimization of industrial-scale processes, future biokinetic CFD studies need to assess multiple types of environmental gradients, like pH, substrate, and dissolved oxygen, especially at industrial scale. 相似文献
18.
Noorman H 《Biotechnology journal》2011,6(8):934-943
For industrial bioreactor design, operation, control and optimization, the scale-down approach is often advocated to efficiently generate data on a small scale, and effectively apply suggested improvements to the industrial scale. In all cases it is important to ensure that the scale-down conditions are representative of the real large-scale bioprocess. Progress is hampered by limited detailed and local information from large-scale bioprocesses. Complementary to real fermentation studies, physical aspects of model fluids such as air-water in large bioreactors provide useful information with limited effort and cost. Still, in industrial practice, investments of time, capital and resources often prohibit systematic work, although, in the end, savings obtained in this way are trivial compared to the expenses that result from real process disturbances, batch failures, and non-flyers with loss of business opportunity. Here we try to highlight what can be learned from real large-scale bioprocess in combination with model fluid studies, and to provide suitable computation tools to overcome data restrictions. Focus is on a specific well-documented case for a 30-m(3) bioreactor. Areas for further research from an industrial perspective are also indicated. 相似文献
19.
Michaela Helmel Martina Marchetti-Deschmann Martin Raus Andreas E. Posch Christoph Herwig Marek Šebela Günter Allmaier 《Analytical biochemistry》2015
Penicillin production during a fermentation process using industrial strains of Penicillium chrysogenum is a research topic permanently discussed since the accidental discovery of the antibiotic. Intact cell mass spectrometry (ICMS) can be a fast and novel monitoring tool for the fermentation progress during penicillin V production in a nearly real-time fashion. This method is already used for the characterization of microorganisms and the differentiation of fungal strains; therefore, the application of ICMS to samples directly harvested from a fermenter is a promising possibility to get fast information about the progress of fungal growth. After the optimization of the ICMS method to penicillin V fermentation broth samples, the obtained ICMS data were evaluated by hierarchical cluster analysis or an in-house software solution written especially for ICMS data comparison. Growth stages of a batch and fed-batch fermentation of Penicillium chrysogenum are differentiated by one of those statistical approaches. The application of two matrix-assisted laser desorption/ionization time-of-flight (MALDI–TOF) instruments in the linear positive ion mode from different vendors demonstrated the universal applicability of the developed ICMS method. The base for a fast and easy-to-use method for monitoring the fermentation progress of P. chrysogenum is created with this ICMS method developed especially for fermentation broth samples. 相似文献
20.
Tuberculosis is a common, and in many cases lethal, infectious disease caused by various strains of Mycobacterium, usually Mycobacterium tuberculosis. (Kumar et al., 2007) In addition, co-infection with Mycobacterium tuberculosis and HIV (TB/HIV), especially in Africa, and multidrug resistant and extensively drug-resistant tuberculosis in all regions, (WHO, 2010) makes it important to develop novel therapeutics against this bacterium. Penicillin like β-Lactam antibiotics are among the most clinically prescribed drugs for anti-bacterial therapeutics. The general mechanism of action involved the inhibition of enzyme d,d-transpeptidases, which takes part in the biosynthesis of the bacterial cell wall (Heesemann, 1993). A major strategy of bacterial resistance to β-lactams is the production of β-lactamases that catalyze the hydrolysis of β-lactams, leading to the inactivation of the antibiotics. β-Lactams have not been used in clinical practice to treat TB infections, because an active penicillinase was reported in M. tuberculosis (Lessel, 1996). BlaC is a class A β-lactamase that contains a nucleophilic serine residue (Ser70) and shares sequence homology with the penicillin-binding protein domain of the ancestral d,d-transpeptidases. Recent studies including our lab show that β-lactam drugs like Clavulanate, Carbapenem, and Meropenem are used primarily against this type of resistant bacteria (Hugonnet et al., 2009). β-lactamase induces the same acetylating reaction with all of these drugs but cannot induce deacetylation. As a result, those drugs remain attached with β-lactamase even after the distortion of their β-lactam ring. At this time, secondary treatment has been done by applying previously used potent penicillin like β-lactam drugs with this primarily treated β-lactamase. In current study, we conducted kinetic and mass spectrometric analysis of different BlaC inhibitors, like NXL104 (Xu et al., 2012) and showed that how they quantitatively inactivates BlaC by forming a carbamyl linkage with the enzyme. In addition, we determined the three-dimensional structures of the different reactive forms of these drugs for better understanding the undergoing mechanisms involved in this inhibition process. Based on our understanding, we are trying to develop novel small molecules with better inhibitory process. 相似文献