scholarly journals Characterization and Development of Osmotolerant Caldicellulosiruptor Strains Targeting Enhanced Hydrogen Production from Lignocellulosic Hydrolysates

2020 ◽  
Author(s):  
Eoin Byrne ◽  
Johanna Björkmalm ◽  
James Bostick ◽  
Krishnan Sreeni ◽  
Karin Willquist ◽  
...  
Keyword(s):  
Hydraulic Retention Time ◽  
Monod Kinetics ◽  
Theoretical Limit ◽  
Carbon Yield ◽  
Adaptive Laboratory Evolution ◽  
Kinetic Growth ◽  
Wide Range ◽  
Elevated Glucose ◽  
Lignocellulose Hydrolysates ◽  
Sugar Conversion

Abstract Background The members of the genus Caldicellulosiruptor have the potential for future integration into a biorefinery system due to their capacity to generate hydrogen close to the theoretical limit of 4 mol H 2 /mol hexose, use a wide range of sugars and can grow on numerous lignocellulose hydrolysates. However, members of this genus are unable to survive in high osmolarity conditions, limiting their ability to grow on more concentrated hydrolysates, thus impeding their industrial applicability. In this study five members of this genus, C. owensensis , C. kronotskyensis , C. bescii, C. acetigenus and C. kristjanssonii , were developed to tolerate higher osmolarities through an adaptive laboratory evolution (ALE) process. The developed strain C. owensensis CO80 was further studied accompanied by the development of a kinetic model based on Monod kinetics. Results Osmotolerant strains of Caldicellulosiruptor were obtained with C. owensensis adapted to grow up to 80 g/l glucose; other strains in particular C. kristjanssonii demonstrated a greater restriction to adaptation. C. owensensis CO80 was further studied and demonstrated the ability to grow in glucose concentrations up to 80 g/l glucose but with reduced volumetric hydrogen productivities (Q H2 ) and incomplete sugar conversion at elevated glucose concentrations. In addition, the carbon yield decreased with elevated concentrations of glucose. The ability of C. owensensis CO80 to grow in high glucose concentrations was further described with a kinetic growth model, which revealed that the critical osmolarity of the cells increased fourfold when cultivated at higher osmolarity. When co-cultured with the osmotolerant strain C. saccharolyticus G5 at a hydraulic retention time (HRT) of 20h, C. owensensis constituted only 0.09-1.58% of the population in suspension.Conclusions The adaptation of members of the Caldicellulosiruptor genus to higher osmolarity established that the ability to develop improved strains via ALE is species dependent, with C. owensensis adapted to grow on 80 g/l, whereas C. kristjanssonii could only be adapted to 30 g/l glucose. Although, C. owensensis CO80 was adapted to a higher osmolarity medium, the strain demonstrated reduced Q H2 with elevated glucose concentrations. This would indicate that while ALE permits adaptation to elevated osmolarities, this approach does not result in improved fermentation performances at these higher osmolarities. Moreover, the observation that planktonic culture of CO80 was outcompeted by an osmotolerant strain of C. saccharolyticus, when co-cultivated in continuous mode, indicates that the robustness of strain CO80 should be improved for industrial application .

scholarly journals Characterization and adaptation of Caldicellulosiruptor strains to higher sugar concentrations, targeting enhanced hydrogen production from lignocellulosic hydrolysates

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Eoin Byrne ◽  
Johanna Björkmalm ◽  
James P. Bostick ◽  
Krishnan Sreenivas ◽  
Karin Willquist ◽  
...  
Keyword(s):  
Mixed Culture ◽  
Mixed Population ◽  
Sugar Concentration ◽  
Monod Kinetics ◽  
Adaptive Laboratory Evolution ◽  
Kinetic Growth ◽  
Wide Range ◽  
Elevated Glucose ◽  
Lignocellulose Hydrolysates ◽  
Sugar Conversion

Abstract Background The members of the genus Caldicellulosiruptor have the potential for future integration into a biorefinery system due to their capacity to generate hydrogen close to the theoretical limit of 4 mol H2/mol hexose, use a wide range of sugars and can grow on numerous lignocellulose hydrolysates. However, members of this genus are unable to survive in high sugar concentrations, limiting their ability to grow on more concentrated hydrolysates, thus impeding their industrial applicability. In this study five members of this genus, C.owensensis, C. kronotskyensis, C.bescii, C.acetigenus and C.kristjanssonii, were developed to tolerate higher sugar concentrations through an adaptive laboratory evolution (ALE) process. The developed mixed population C.owensensis CO80 was further studied and accompanied by the development of a kinetic model based on Monod kinetics to quantitatively compare it with the parental strain. Results Mixed populations of Caldicellulosiruptor tolerant to higher glucose concentrations were obtained with C.owensensis adapted to grow up to 80 g/L glucose; other strains in particular C. kristjanssonii demonstrated a greater restriction to adaptation. The C.owensensis CO80 mixed population was further studied and demonstrated the ability to grow in glucose concentrations up to 80 g/L glucose, but with reduced volumetric hydrogen productivities ($$Q_{{{\text{H}}_{2} }}$$ Q H 2 ) and incomplete sugar conversion at elevated glucose concentrations. In addition, the carbon yield decreased with elevated concentrations of glucose. The ability of the mixed population C.owensensis CO80 to grow in high glucose concentrations was further described with a kinetic growth model, which revealed that the critical sugar concentration of the cells increased fourfold when cultivated at higher concentrations. When co-cultured with the adapted C.saccharolyticus G5 mixed culture at a hydraulic retention time (HRT) of 20 h, C.owensensis constituted only 0.09–1.58% of the population in suspension. Conclusions The adaptation of members of the Caldicellulosiruptor genus to higher sugar concentrations established that the ability to develop improved strains via ALE is species dependent, with C.owensensis adapted to grow on 80 g/L, whereas C.kristjanssonii could only be adapted to 30 g/L glucose. Although C.owensensis CO80 was adapted to a higher sugar concentration, this mixed population demonstrated reduced $$Q_{{{\text{H}}_{2} }}$$ Q H 2 with elevated glucose concentrations. This would indicate that while ALE permits adaptation to elevated sugar concentrations, this approach does not result in improved fermentation performances at these higher sugar concentrations. Moreover, the observation that planktonic mixed culture of CO80 was outcompeted by an adapted C.saccharolyticus, when co-cultivated in continuous mode, indicates that the robustness of CO80 mixed culture should be improved for industrial application.

scholarly journals Assessing the factors influencing the performance of constructed wetland–microbial fuel cell integration

2020 ◽  
Vol 81 (4) ◽  
pp. 631-643 ◽  
Author(s):  
Huang Jingyu ◽  
Nicholas Miwornunyuie ◽  
David Ewusi-Mensah ◽  
Desmond Ato Koomson
Keyword(s):  
Wastewater Treatment ◽  
Fuel Cell ◽  
Microbial Fuel Cell ◽  
Constructed Wetland ◽  
Retention Time ◽  
Electricity Generation ◽  
Electrode Materials ◽  
Hydraulic Retention Time ◽  
Wetland Plants ◽  
Wide Range

Abstract Constructed wetland coupled microbial fuel cell (CW-MFC) systems integrate an aerobic zone and an anaerobic zone to treat wastewater and to generate bioenergy. The concept evolves based on the principles of constructed wetlands and plant MFC (one form of photosynthetic MFC) technologies, of which all contain plants. CW-MFC have been used in a wide range of application since their introduction in 2012 for wastewater treatment and electricity generation. However, there are few reports on the individual components and their performance on CW-MFC efficiency. The performance and efficiency of this technology are significantly influenced by several factors such as the organic load and sewage composition, hydraulic retention time, cathode dissolved oxygen, electrode materials and wetland plants. This paper reviews the influence of the macrophyte (wetland plants) component, substrate material, microorganisms, electrode material and hydraulic retention time (HRT) on CW-MFC performance in wastewater treatment and electricity generation. The study assesses the relationship between these parameters and discusses progress in the development of this integrated system to date.

scholarly journals Continuous-flow ozonation over modified ceramsite: implications for the degradation of cation red x-GRL

2018 ◽  
Vol 78 (12) ◽  
pp. 2577-2585
Author(s):  
Ying Liu ◽  
Deli Wu ◽  
Hongping He
Keyword(s):  
Wastewater Treatment ◽  
Retention Time ◽  
Continuous Flow ◽  
Hydraulic Retention Time ◽  
Absorption Capacity ◽  
Catalytic Ozonation ◽  
Utilization Efficiency ◽  
Silty Clay ◽  
Heterogeneous Catalytic ◽  
Wide Range

Abstract Catalytic ozonation has been widely used for refractory dye wastewater treatment due to highly reactive HO·. In this study, a kind of low-cost and environmental-friendly modified ceramsite sphere derived from pyrite cinder, silty clay and kaolin was prepared as ozonation catalyst. The degradation performances of cation red x-GRL were performed under a continuous mode. Being close to the practical treatment, continuous-flow ozonation study is vital for applying heterogeneous catalytic ozonation in wastewater treatment at a large industrial scale. Results showed that the absorption capacity of this modified ceramsite towards cation red x-GRL was confirmed to be slight. The mineralization efficiency was high, accounting for 48.0% of 200 mg/L cation red x-GRL at a constant flow rate of 0.18 L/min (hydraulic retention time = 16 min), while only 7.8% during ozonation alone. Furthermore, this novel catalytic ozonation can maintain high mineralization efficiency in a wide range of pH (3–10), which was ascribed to the synergistic catalytic performance of various oxides. The reaction mechanism is ascribed to the promotion of ·OH production from O3 molecules' decomposition. Moreover, ozone utilization efficiency at hydraulic retention time of 16 min during catalytic ozonation was 2.0 times as high as that during ozonation alone.

scholarly journals Mutant Variants of the Substrate-Binding Protein DppA fromEscherichia coliEnhance Growth on Nonstandard γ-Glutamyl Amide-Containing Peptides

2018 ◽  
Vol 84 (13) ◽  
Author(s):  
Tilmann Kuenzl ◽  
Xiaochun Li-Blatter ◽  
Puneet Srivastava ◽  
Piet Herdewijn ◽  
Timothy Sharpe ◽  
...  
Keyword(s):  
Amino Acid ◽  
Binding Protein ◽  
Substrate Binding ◽  
Building Blocks ◽  
Side Chains ◽  
Adaptive Laboratory Evolution ◽  
Laboratory Evolution ◽  
Wide Range ◽  
Amino Acid Side Chains ◽  
Substrate Binding Protein

ABSTRACTThe import of nonnatural molecules is a recurring problem in fundamental and applied aspects of microbiology. The dipeptide permease (Dpp) ofEscherichia coliis an ABC-type multicomponent transporter system located in the cytoplasmic membrane, which is capable of transporting a wide range of di- and tripeptides with structurally and chemically diverse amino acid side chains into the cell. Given this low degree of specificity, Dpp was previously used as an entry gate to deliver natural and nonnatural cargo molecules into the cell by attaching them to amino acid side chains of peptides, in particular, the γ-carboxyl group of glutamate residues. However, the binding affinity of the substrate-binding protein dipeptide permease A (DppA), which is responsible for the initial binding of peptides in the periplasmic space, is significantly higher for peptides consisting of standard amino acids than for peptides containing side-chain modifications. Here, we used adaptive laboratory evolution to identify strains that utilize dipeptides containing γ-substituted glutamate residues more efficiently and linked this phenotype to different mutations in DppA.In vitrocharacterization of these mutants by thermal denaturation midpoint shift assays and isothermal titration calorimetry revealed significantly higher binding affinities of these variants toward peptides containing γ-glutamyl amides, presumably resulting in improved uptake and therefore faster growth in media supplemented with these nonstandard peptides.IMPORTANCEFundamental and synthetic biology frequently suffer from insufficient delivery of unnatural building blocks or substrates for metabolic pathways into bacterial cells. The use of peptide-based transport vectors represents an established strategy to enable the uptake of such molecules as a cargo. We expand the scope of peptide-based uptake and characterize in detail the obtained DppA mutant variants. Furthermore, we highlight the potential of adaptive laboratory evolution to identify beneficial insertion mutations that are unlikely to be identified with existing directed evolution strategies.

Primary facultative ponds in the UK: the effect of operational parameters on performance and algal populations

2005 ◽  
Vol 51 (12) ◽  
pp. 61-67 ◽  
Author(s):  
K.L. Abis ◽  
D.D. Mara
Keyword(s):  
Rural Communities ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Pilot Scale ◽  
Significant Loss ◽  
Ammonia Removal ◽  
Operational Parameters ◽  
Wide Range ◽  
Significant Difference ◽  
The Uk

Waste stabilisation pond systems in the UK are used to treat effluents from small rural communities where there are large fluctuations in both BOD load and inflow; the facultative ponds in these systems have a wide range of hydraulic retention times: between 11–86 days. Low hydraulic retention times in UK ponds are sometimes accompanied by a high BOD loading, although some have a low BOD loading due to high inflows of dilute wastewater. It is not certain whether the performance is affected by the short hydraulic retention time or high BOD loading. A pilot-scale experiment tested the effect of hydraulic retention time (20–60 days) on primary facultative pond performance whilst keeping the BOD loading constant at 80 kg/ha d. It was found that no significant loss of performance was experienced at the test range for BOD and ammonia removal; some loss in SS removal was noted at 20 days' retention time. The effect of BOD loading on the maintenance of algal populations during winter (November(February) was tested at loadings of 50 and 80 kg/ha d. Although there was a significant difference in the concentrations of chlorophyll a and dissolved oxygen between the two loadings, there was no effect on performance.

scholarly journals Enhanced inhibitor tolerance and increased lipid productivity through adaptive laboratory evolution in the oleaginous yeast Metshnikowia pulcherrima

2020 ◽  
Author(s):  
Robert H. Hicks ◽  
Yuxin Sze ◽  
Christopher J. Chuck ◽  
Daniel A. Henk
Keyword(s):  
Formic Acid ◽  
Oleaginous Yeast ◽  
Lipid Production ◽  
Dry Weight ◽  
Lipid Productivity ◽  
Adaptive Laboratory Evolution ◽  
Stirred Tank Bioreactor ◽  
Inhibitor Tolerance ◽  
Laboratory Evolution ◽  
Wide Range

AbstractMicrobial lipid production from second generation feedstocks presents a sustainable route to future fuels, foods and bulk chemicals. The oleaginous yeast Metshnikowia pulcherrima has previously been investigated as a potential platform organism for lipid production due to its ability to be grown in non-sterile conditions and metabolising a wide range of oligo- and monosaccharide carbon sources within lignocellulosic hydrolysates. However, the generation of inhibitors from depolymerisation causes downstream bioprocessing complications, and despite M. pulcherrima’s comparative tolerance, their presence is deleterious to both biomass and lipid formation. Using either a single inhibitor (formic acid) or an inhibitor cocktail (formic acid, acetic acid, fufural and HMF), two strategies of adaptive laboratory evolution were performed to improve M. pulcherrima’s fermentation inhibitor tolerance. Using a sequential batch culturing approach, the resulting strains from both strategies had increased growth rates and reduced lag times under inhibiting conditions versus the progenitor. Interestingly, the lipid production of the inhibitor cocktail evolved strains markedly increased, with one strain producing 41% lipid by dry weight compared to 22% of the progenitor. The evolved species was cultured in a non-sterile 2L stirred tank bioreactor and accumulated lipid rapidly, yielding 6.1 g/L of lipid (35% cell dry weight) within 48 hours; a lipid productivity of 0.128 g L-1 h-1. Furthermore, the lipid profile was analogous to palm oil, consisting of 39% C16:0 and 56% C18:1 after 48 hours.

scholarly journals Kinetics of Anaerobic Digestion of Unripe Plantain Peels

2020 ◽  
pp. 7-17
Author(s):  
Chinenyenwa Nkeiruka Nweke ◽  
Joseph Tagbo Nwabanne
Keyword(s):  
Anaerobic Digestion ◽  
Hydraulic Retention Time ◽  
Biogas Production ◽  
Growth Yield ◽  
Second Order ◽  
Coefficient Of Determination ◽  
Monod Kinetics ◽  
Order Model ◽  
First Order ◽  
Kinetics Of

This study was carried out to investigate the biogas production obtained from anaerobic digestion of unripe plantain peels (PP) and the kinetics of the digestion process. 400 g of dried and shredded unripe plantain peels were mixed with 200 ml of water and put into 1 L digester and observed for biogas for hydraulic retention time (HRT) of 15 days by the method of downwards displacement. The cumulative biogas volume obtained after digestion was 285 ml. The COD removal efficiency of 72.5% was achieved. The kinetics of PP digestion was evaluated using first order, Monod, Contois and, Grau second-order models. Results showed that the kinetics of anaerobic digestion of PP followed the first-order model with a constant (K) of 0.095 day-1. Monod kinetics was evaluated and the maximum rate of substrate utilization (K), the half velocity constant (KS), endogenous decay coefficient (Kd), biomass growth yield (Y) and, maximum specific microorganism growth rate (µmax) obtained were 0.7615 day-1, 16.20 mg/l, 0.0047 day-1, 0.0112 mgVSS mgCOD-1 and, 0.009 day-1 respectively. These results revealed that inoculation would be required to increase the rate and volume of biogas production. Both first-order and Monod models gave a high coefficient of determination indicating that first order and Monod models can be used to model the digestion of PP. Contois model gave values of µmax and β as 0.011 day-1 and 0.644 mgCOD mgVSS-1 respectively. The result obtained has shown that the digestion of PP did not follow second-order kinetics.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

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