The inhibition of the maximum specific growth and fermentation rate of <i>Zymomonas mobilis</i> by ethanol

Jöbses, I. M. L.; Roels, J. A.

doi:10.1002/bit.260280412

Cited by 54 publications

(27 citation statements)

References 31 publications

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“…A difference between the inhibitory effect of added and produced ethanol, in conjunction with different intracellular and extracellular ethanol concentrations, was proposed for yeast in studies prior to 1983 (34,479,497). However, subsequent unrebutted work has discounted this hypothesis for yeast (133,134,135,229,395), Z. mobilis (313), and E. coli (168). In light of these data and in particular biophysical analyses indicating that substantial differences between intracellular and extracellular ethanol concentrations across plasma membranes can exist for at most short periods (313,395), it would appear unlikely that this discrepancy is due to a difference in the inhibitory effect of added and produced ethanol.…”

Section: Native Cellulolytic Strategymentioning

confidence: 99%

Microbial Cellulose Utilization: Fundamentals and Biotechnology

Lynd

Weimer

Zyl³

et al. 2002

Microbiol Mol Biol Rev

4,047

2,868

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Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for “consolidated bioprocessing” (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts

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Section: Native Cellulolytic Strategymentioning

confidence: 99%

Microbial Cellulose Utilization: Fundamentals and Biotechnology

Lynd

Weimer

Zyl³

et al. 2002

Microbiol Mol Biol Rev

4,047

2,868

View full text Add to dashboard Cite

show abstract

“…To accurately describe the formation rate of the key component at low ethanol concentrations and under substrate-limited conditions, the formation rate expression for the key component [34,35] is a function of substrate concentration, given by:…”

Section: Bioethanol Manufacturing Process Modelmentioning

confidence: 99%

“…However, typical models consider only the kinetic expressions of fermentation for constant temperature conditions. The proposed mathematical model here takes into consideration the temperature effect on kinetics parameters, mass and heat transfer, in addition to the kinetic equations modified from the indirect inhibition structural model developed in the literature [34,35].…”

Section: Bioethanol Manufacturing Process Modelmentioning

confidence: 99%

Development of Chemical Process Design and Control for Sustainability

Mirlekar

Ruiz-Mercado

et al. 2016

Processes

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This contribution describes a novel process systems engineering framework that couples advanced control with sustainability evaluation for the optimization of process operations to minimize environmental impacts associated with products, materials and energy. The implemented control strategy combines a biologically-inspired method with optimal control concepts for finding more sustainable operating trajectories. The sustainability assessment of process operating points is carried out by using the U.S. EPA's Gauging Reaction Effectiveness for the ENvironmental Sustainability of Chemistries with a multi-Objective Process Evaluator (GREENSCOPE) tool that provides scores for the selected indicators in the economic, material efficiency, environmental and energy areas. The indicator scores describe process performance on a sustainability measurement scale, effectively determining which operating point is more sustainable if there are more than several steady states for one specific product manufacturing. Through comparisons between a representative benchmark and the optimal steady states obtained through the implementation of the proposed controller, a systematic decision can be made in terms of whether the implementation of the controller is moving the process towards a more sustainable operation. The effectiveness of the proposed framework is illustrated through a case study of a continuous fermentation process for fuel production, whose material and energy time variation models are characterized by multiple steady states and oscillatory conditions.

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“…It has previously been shown that a FBF for ethanol production from glucose by naturally immobilized Zymomonas mobilis could be operated with D > 11μ max [10]. Because the volumetric productivity (r p ) of this system was about 10-times higher than μ max at the ethanol concentration being produced [11], this is evidence that there was a low degree of diffusional limitation within the Zymomonas biofilm. In contrast, experimental work with flocculent yeast in a diffusion cell has shown that the rate of glucose diffusion was only 17% compared to the rate in pure water [12].…”

Section: Introductionmentioning

confidence: 87%

Natural immobilisation of microorganisms for continuous ethanol production

Baptista

Cóias

Oliveira

et al. 2006

Enzyme and Microbial Technology

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Using a growth medium based on cane blackstrap molasses, we compared ethanol production by two strains of Saccharomyces cerevisiae that were immobilized in polyurethane foam cubes in a fluidised-bed fermenter. One strain (NCYC 1119) was adhesive and extremely flocculent, whilst the other strain was not adhesive and only weakly flocculent. The strong flocs of NCYC 1119 caused blockage of the bed, so that stable operation could not be achieved beyond 15 days. Nevertheless, it was able to produce 40 g L −1 ethanol at a rate up to 16 g L −1 h −1 (D = 0.4 h −1 ), although this production period was limited to 192 h. In contrast, the non-adhesive strain was only capable of producing 28 g L −1 ethanol at a rate of 11 g Lat the same dilution rate, even though production continued for 576 h. Despite the conversion of sugars to ethanol not being complete during these trials (up to 47 g L −1 was expected), it was clearly demonstrated that the productivity of the adhesive strain was higher than that of the non-adhesive one. However, further work is required to develop this process into a robust, industrial system.

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The inhibition of the maximum specific growth and fermentation rate of Zymomonas mobilis by ethanol

Cited by 54 publications

References 31 publications

Microbial Cellulose Utilization: Fundamentals and Biotechnology

Microbial Cellulose Utilization: Fundamentals and Biotechnology

Development of Chemical Process Design and Control for Sustainability

Natural immobilisation of microorganisms for continuous ethanol production

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