scholarly journals Syntrophic co-culture amplification of production phenotype for high-throughput screening of microbial strain libraries

2019 ◽  
Author(s):  
Tatyana E. Saleski ◽  
Alissa R. Kerner ◽  
Meng Ting Chung ◽  
Corine M. Jackman ◽  
Azzaya Khasbaatar ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Parent Strain ◽  
Dynamic Range ◽  
Random Mutagenesis ◽  
Spatial Separation ◽  
List Type ◽  
Target Molecule ◽  
Wide Range ◽  
Target Molecules

AbstractMicrobes can be engineered to synthesize a wide array of bioproducts, yet production phenotype evaluation remains a frequent bottleneck in the design-build-test cycle where strain development requires iterative rounds of library construction and testing. Here, we presentSyntrophicCo-cultureAmplification ofProduction phenotype (SnoCAP). Through a metabolic cross-feeding circuit, the production level of a target molecule is translated into highly distinguishable co-culture growth characteristics, which amplifies differences in production into highly distinguishable growth phenotypes. We demonstrate SnoCAP with the screening ofEscherichia colistrains for production of two target molecules: 2-ketoisovalerate, a precursor of the drop-in biofuel isobutanol, and L-tryptophan. The dynamic range of the screening can be tuned by employing an inhibitory analog of the target molecule. Screening based on this framework requires compartmentalization of individual producers with the sensor strain. We explore three formats of implementation with increasing throughput capability: confinement in microtiter plates (102-104assays/experiment), spatial separation on agar plates (104-105assays/experiment), and encapsulation in microdroplets (105-107assays/experiment). Using SnoCAP, we identified an efficient isobutanol production strain from a random mutagenesis library, reaching a final titer that is 5-fold higher than that of the parent strain. The framework can also be extended to screening for secondary metabolite production using a push-pull strategy. We expect that SnoCAP can be readily adapted to the screening of various microbial species, to improve production of a wide range of target molecules.HighlightsA high-throughput screening platform based on cross-feeding auxotrophs was developed.Compartmentalization was implemented in three formats: microplates, agar plates, and microdroplets.Utility of the screening was demonstrated for two proof-of-concept target molecules: 2-ketoisovalerate and L-tryptophan.The assay dynamic range was tuned by addition of an inhibitory analog.The screening was applied to identify a strain from a chemically mutagenized library that produces 5-fold higher isobutanol titer than the parent strain.

High-Throughput Mass Spectrometry for Hit Identification: Current Landscape and Future Perspectives

2021 ◽  
Vol 26 (2) ◽  
pp. 168-191
Author(s):  
David G. McLaren ◽  
Vinit Shah ◽  
Thomas Wisniewski ◽  
Lucien Ghislain ◽  
Chang Liu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Throughput ◽  
High Throughput Screening ◽  
Dynamic Range ◽  
Direct Detection ◽  
Label Free ◽  
Physiological Relevance ◽  
Wide Range ◽  
And Performance ◽  
Sensitivity Specificity

For nearly two decades mass spectrometry has been used as a label-free, direct-detection method for both functional and affinity-based screening of a wide range of therapeutically relevant target classes. Here, we present an overview of several established and emerging mass spectrometry platforms and summarize the unique strengths and performance characteristics of each as they apply to high-throughput screening. Multiple examples from the recent literature are highlighted in order to illustrate the power of each individual technique, with special emphasis given to cases where the use of mass spectrometry was found to be differentiating when compared with other detection formats. Indeed, as many of these examples will demonstrate, the inherent strengths of mass spectrometry—sensitivity, specificity, wide dynamic range, and amenability to complex matrices—can be leveraged to enhance the discriminating power and physiological relevance of assays included in screening cascades. It is our hope that this review will serve as a useful guide to readers of all backgrounds and experience levels on the applicability and benefits of mass spectrometry in the search for hits, leads, and, ultimately, drugs.

Directed Evolution of P450 Fatty Acid Decarboxylases via High-Throughput Screening Towards Improved Catalytic Activity

2019 ◽  
Author(s):  
Huifang Xu ◽  
Weinan Liang ◽  
Linlin Ning ◽  
Yuanyuan Jiang ◽  
Wenxia Yang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Fatty Acid ◽  
Directed Evolution ◽  
High Throughput ◽  
High Throughput Screening ◽  
Colorimetric Detection ◽  
Screening Method ◽  
Random Mutagenesis ◽  
Direct Production ◽  
Consumption Activity

P450 fatty acid decarboxylases (FADCs) have recently been attracting considerable attention owing to their one-step direct production of industrially important 1-alkenes from biologically abundant feedstock free fatty acids under mild conditions. However, attempts to improve the catalytic activity of FADCs have met with little success. Protein engineering has been limited to selected residues and small mutant libraries due to lack of an effective high-throughput screening (HTS) method. Here, we devise a catalase-deficient <i>Escherichia coli</i> host strain and report an HTS approach based on colorimetric detection of H<sub>2</sub>O<sub>2</sub>-consumption activity of FADCs. Directed evolution enabled by this method has led to effective identification for the first time of improved FADC variants for medium-chain 1-alkene production from both DNA shuffling and random mutagenesis libraries. Advantageously, this screening method can be extended to other enzymes that stoichiometrically utilize H<sub>2</sub>O<sub>2</sub> as co-substrate.

scholarly journals Rapid and Sensitive Quantification of Intracellular Glycyl-Sarcosine for Semi-High-Throughput Screening for Inhibitors of PEPT-1

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1019
Author(s):  
Teresa von Linde ◽  
Gzona Bajraktari-Sylejmani ◽  
Walter E. Haefeli ◽  
Jürgen Burhenne ◽  
Johanna Weiss ◽  
...  
Keyword(s):  
Sample Preparation ◽  
High Throughput ◽  
High Throughput Screening ◽  
Dynamic Range ◽  
High Sensitivity ◽  
Peptide Bond ◽  
Peptide Transporter ◽  
Systemic Absorption ◽  
Screening Assay ◽  
Limit Of Quantification

The peptide transporter PEPT-1 (SLC15A1) plays a major role in nutritional supply with amino acids by mediating the intestinal influx of dipeptides and tripeptides generated during food digestion. Its role in the uptake of small bioactive peptides and various therapeutics makes it an important target for the investigation of the systemic absorption of small peptide-like active compounds and prodrug strategies of poorly absorbed therapeutics. The dipeptide glycyl-sarcosine (Gly-Sar), which comprises an N-methylated peptide bond that increases stability against enzymatic degradation, is widely utilized for studying PEPT-1-mediated transport. To support experiments on PEPT-1 inhibitor screening to identify potential substrates, we developed a highly sensitive Gly-Sar quantification assay for Caco-2 cell lysates with a dynamic range of 0.1 to 1000 ng/mL (lower limit of quantification 0.68 nM) in 50 µL of cell lysate. The assay was validated following the applicable recommendations for bioanalytic method validation of the FDA and EMA. Sample preparation and quantification were established in 96-well cell culture plates that were also used for the cellular uptake studies, resulting in a rapid and robust screening assay for PEPT-1 inhibitors. This sample preparation principle, combined with the high sensitivity of the UPLC-MS/MS quantification, is suitable for screening assays for PEPT-1 inhibitors and substrates in high-throughput formats and holds the potential for automation. Applicability was demonstrated by IC50 determinations of the known PEPT-1 inhibitor losartan, the known substrates glycyl-proline (Gly-Pro), and valaciclovir, the prodrug of aciclovir, which itself is no substrate of PEPT-1 and consequently showed no inhibition in our assay.

scholarly journals Directed Evolution of Aptamer Discovery Technologies

2021 ◽  
Author(s):  
Diana Wu ◽  
Chelsea Gordon ◽  
John Shin ◽  
Michael Eisenstein ◽  
Hyongsok Tom Soh
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Click Reaction ◽  
Clinical Diagnostics ◽  
High Quality ◽  
Affinity Reagents ◽  
Wide Range ◽  
Target Binding ◽  
Modified Nucleobases ◽  
Parallel Fashion

Although antibodies are a powerful tool for molecular biology and clinical diagnostics, there are many emerging applications for which nucleic acid-based aptamers can be advantageous. However, generating high-quality aptamers with sufficient affinity and specificity for biomedical applications is a challenging feat for most research laboratories. In this Account, we describe four techniques developed in our lab to accelerate the discovery of high quality aptamer reagents that can achieve robust binding even for challenging molecular targets. The first method is particle display, in which we convert solution-phase aptamers into aptamer particles that can be screened via fluorescence-activated cell sorting (FACS) to quantitatively isolate individual aptamer particles based on their affinity. This enables the efficient isolation of high-affinity aptamers in fewer selection rounds than conventional methods, thereby minimizing selection biases and reducing the emergence of artifacts in the final aptamer pool. We subsequently developed the multi-parametric particle display (MPPD) method, which employs two-color FACS to isolate aptamer particles based on both affinity and specificity, yielding aptamers that exhibit excellent target binding even in complex matrices like serum. The third method is a click chemistry-based particle display (click-PD) that enables the generation and high-throughput screening of non-nattural aptamers with a wide range of base modifications. We have shown that these base-modified aptamers can achieve robust affinity and specificity for targets that have proven challenging or inaccessible with natural nucleotide-based aptamer libraries. Lastly, we describe the non-natural aptamer array (N2A2) platform, in which a modified benchtop sequencing instrument is used to characterize base-modified aptamers in a massively parallel fashion, enabling the efficient identification of molecules with excellent affinity and specificity for their targets. This system first generates aptamer clusters on the flow-cell surface that incorporate alkyne-modified nucleobases, and then performs a click reaction to couple those nucleobases to an azide-modified chemical moiety. This yields a sequence-defined array of tens of millions of base-modified sequences, which can then be characterized in a high-throughput fashion. Collectively, we believe that these advancements are helping to make aptamer technology more accessible, efficient, and robust, thereby enabling the use of these affinity reagents for a wider range of molecular recognition and detection-based applications.

Rapid generation of Hybrid Biochemical/Mechanical Cues in Heterogeneous Droplets for High-Throughput Screening of Cellular Response

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Xing Zhao ◽  
Gaozhi Ou ◽  
Mengcheng Lei ◽  
Yang Zhang ◽  
Lina Li ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
High Throughput ◽  
High Throughput Screening ◽  
Cellular Response ◽  
Wide Range ◽  
Rapid Generation ◽  
P Cells

Cells in native microenvironment are subjected to varying combinations of biochemical cues and mechanical cues in a wide range. Despite many signaling pathways have been found to be responsive for...

scholarly journals Hydrogen overproducing nitrogenases obtained by random mutagenesis and high-throughput screening

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Emma Barahona ◽  
Emilio Jiménez-Vicente ◽  
Luis M. Rubio
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Rhodobacter Capsulatus ◽  
Random Mutagenesis ◽  
Fluorescence Emission ◽  
Inducible Promoter ◽  
Hydrogen Gas ◽  
Photosynthetic Organisms ◽  
Fe Protein ◽  
Protein Variants

Abstract When produced biologically, especially by photosynthetic organisms, hydrogen gas (H2) is arguably the cleanest fuel available. An important limitation to the discovery or synthesis of better H2-producing enzymes is the absence of methods for the high-throughput screening of H2 production in biological systems. Here, we re-engineered the natural H2 sensing system of Rhodobacter capsulatus to direct the emission of LacZ-dependent fluorescence in response to nitrogenase-produced H2. A lacZ gene was placed under the control of the hupA H2-inducible promoter in a strain lacking the uptake hydrogenase and the nifH nitrogenase gene. This system was then used in combination with fluorescence-activated cell sorting flow cytometry to screen large libraries of nitrogenase Fe protein variants generated by random mutagenesis. Exact correlation between fluorescence emission and H2 production levels was found for all automatically selected strains. One of the selected H2-overproducing Fe protein variants lacked 40% of the wild-type amino acid sequence, a surprising finding for a protein that is highly conserved in nature. We propose that this method has great potential to improve microbial H2 production by allowing powerful approaches such as the directed evolution of nitrogenases and hydrogenases.

scholarly journals In Vivo, High-Throughput Selection of Thermostable Cyclohexanone Monooxygenase (CHMO)

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 935
Author(s):  
Sarah Maxel ◽  
Linyue Zhang ◽  
Edward King ◽  
Ana Paula Acosta ◽  
Ray Luo ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Rational Design ◽  
Random Mutagenesis ◽  
Residual Activity ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Coli Strain ◽  
Screening Tools ◽  
Cyclohexanone Monooxygenase

Cyclohexanone monooxygenase (CHMO) from Acinetobacter sp. NCIMB 9871 is characterized as having wide substrate versatility for the biooxidation of (cyclic) ketones into esters and lactones with high stereospecificity. Despite industrial potential, CHMO usage is restricted by poor thermostability. Limited high-throughput screening tools and challenges in rationally engineering thermostability have impeded CHMO engineering efforts. We demonstrate the application of an aerobic, high-throughput growth selection platform in Escherichia coli (strain MX203) for the discovery of thermostability enhancing mutations for CHMO. The selection employs growth for the easy readout of CHMO activity in vivo, by requiring nicotinamide adenine dinucleotide phosphate (NADPH)-consuming enzymes to restore cellular redox balance. In the presence of the native substrate cyclohexanone, variant CHMO GV (A245G-A288V) was discovered from a random mutagenesis library screened at 42 °C. This variant retained native activity, exhibited ~4.4-fold improvement in residual activity after 30 °C incubation, and demonstrated ~5-fold higher cyclohexanone conversion at 37 °C compared to the wild type. Molecular modeling indicates that CHMO GV experiences more favorable residue packing and supports additional backbone hydrogen bonding. Further rational design resulted in CHMO A245G-A288V-T415C with improved thermostability at 45 °C. Our platform for oxygenase evolution enabled the rapid engineering of protein stability critical for industrial scalability.

SoftBV – a software tool for screening the materials genome of inorganic fast ion conductors

2019 ◽  
Vol 75 (1) ◽  
pp. 18-33 ◽  
Author(s):  
Haomin Chen ◽  
Lee Loong Wong ◽  
Stefan Adams
Keyword(s):  
Force Field ◽  
High Throughput ◽  
High Throughput Screening ◽  
Density Functional ◽  
Inorganic Compounds ◽  
Computational Cost ◽  
Lewis Base ◽  
Computational Screening ◽  
Wide Range ◽  
Dft Simulations

The identification of materials for advanced energy-storage systems is still mostly based on experimental trial and error. Increasingly, computational tools are sought to accelerate materials discovery by computational predictions. Here are introduced a set of computationally inexpensive software tools that exploit the bond-valence-based empirical force field previously developed by the authors to enable high-throughput computational screening of experimental or simulated crystal-structure models of battery materials predicting a variety of properties of technological relevance, including a structure plausibility check, surface energies, an inventory of equilibrium and interstitial sites, the topology of ion-migration paths in between those sites, the respective migration barriers and the site-specific attempt frequencies. All of these can be predicted from CIF files of structure models at a minute fraction of the computational cost of density functional theory (DFT) simulations, and with the added advantage that all the relevant pathway segments are analysed instead of arbitrarily predetermined paths. The capabilities and limitations of the approach are evaluated for a wide range of ion-conducting solids. An integrated simple kinetic Monte Carlo simulation provides rough (but less reliable) predictions of the absolute conductivity at a given temperature. The automated adaptation of the force field to the composition and charge distribution in the simulated material allows for a high transferability of the force field within a wide range of Lewis acid–Lewis base-type ionic inorganic compounds as necessary for high-throughput screening. While the transferability and precision will not reach the same levels as in DFT simulations, the fact that the computational cost is several orders of magnitude lower allows the application of the approach not only to pre-screen databases of simple structure prototypes but also to structure models of complex disordered or amorphous phases, and provides a path to expand the analysis to charge transfer across interfaces that would be difficult to cover by ab initio methods.

scholarly journals Colloidal Aggregate Detection by Rapid Fluorescence Measurement of Liquid Surface Curvature Changes in Multiwell Plates

2007 ◽  
Vol 12 (7) ◽  
pp. 966-971 ◽  
Author(s):  
Lifeng Cai ◽  
Miriam Gochin
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Dynamic Range ◽  
Liquid Surface ◽  
Enzyme Inhibitor ◽  
Fluorescence Emission ◽  
Fluorescence Measurement ◽  
Screening Assay ◽  
Colloidal Aggregate ◽  
Multiwell Plates

A simple fluorescence method is reported for the detection of colloidal aggregate formation in solution, with specific applications to determine the critical micelle concentration (CMC) of surfactants and detect small-molecule promiscuous inhibitors. The method exploits the meniscus curvature changes in high-density multiwell plates associated with colloidal changes in solution. The shape of the meniscus has a significant effect on fluorescence intensity when detected using a top-read fluorescence plate reader because of the effect of total internal reflection on fluorescence emission through a curved liquid surface. A dynamic range of 60% is calculated and observed and is measured with a relative sensitivity of 2%. Facile determination of the CMC of a variety of surfactants is demonstrated, as well as a screening assay for aggregate forming properties of small drug-like compounds, a common cause of promiscuous inhibition in high-throughput screening (HTS) enzyme inhibitor assays. Our preliminary results show a potential HTS assay with Z′ factor of 0.76, with good separation between aggregating and nonaggregating small molecules. The method combines the high sensitivity and universality of classic surface tension methods with simplicity and high-throughput determination, enabling facile detection of molecular interactions involving a change in liquid or solid surface character. ( Journal of Biomolecular Screening 2007:966-971)

scholarly journals High-Throughput Screening of Metal–organic Frameworks for Macroscale Heteroepitaxial Alignment

2018 ◽  
Author(s):  
Andrew Tarzia ◽  
Masahide Takahashi ◽  
Paolo Falcaro ◽  
Aaron Thornton ◽  
Christian Doonan ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Defect Formation ◽  
Metal Organic Frameworks ◽  
Rectangular Lattice ◽  
Copper Hydroxide ◽  
Computational Screening ◽  
Screening Algorithm ◽  
Wide Range ◽  
Metal Organic

The ability to align porous metal–organic frameworks (MOFs) on substrate surfaces on a macroscopic scale is a vital step towards integrating MOFs into functional devices. But macroscale surface alignment of MOF crystals has only been demonstrated in a few cases. To accelerate the materials discovery process, we have developed a high-throughput computational screening algorithm to identify MOFs that are likely to undergo macroscale aligned heterepitaxial growth on a substrate. Screening of thousands of MOF structures by this process can be achieved in a few days on a desktop workstation. The algorithm filters MOFs based on surface chemical compatibility, lattice matching with the substrate, and interfacial bonding. Our method uses a simple new computationally efficient measure of the interfacial energy that considers both bond and defect formation at the interface. Furthermore, we show that this novel descriptor is a better predictor of aligned heteroepitaxial growth than other established interface descriptors, by testing our screening algorithm on a sample set of copper MOFs that have been grown heteroepitaxially on a copper hydroxide surface. Application of the screening process to several MOF databases reveals that the top candidates for aligned growth on copper hydroxide comprise mostly MOFs with rectangular lattice symmetry in the plane of the substrate. This result indicates a substrate-directing effect that could be exploited in targeted synthetic strategies. We also identify that MOFs likely to form aligned heterostructures have broad distributions of in-plane pore sizes and anisotropies. Accordingly, this suggests that aligned MOF thin films with a wide range of properties may be experimentally accessible.

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