1
|
Synergistic co-utilization of biomass-derived sugars enhances aromatic amino acid production by engineered Escherichia coli. Biotechnol Bioeng 2024; 121:784-794. [PMID: 37926950 DOI: 10.1002/bit.28585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/30/2023] [Accepted: 10/18/2023] [Indexed: 11/07/2023]
Abstract
Efficient co-utilization of mixed sugar feedstocks remains a biomanufacturing challenge, thus motivating ongoing efforts to engineer microbes for improved conversion of glucose-xylose mixtures. This study focuses on enhancing phenylalanine production by engineering Escherichia coli to efficiently co-utilize glucose and xylose. Flux balance analysis identified E4P flux as a bottleneck which could be alleviated by increasing the xylose-to-glucose flux ratio. A mutant copy of the xylose-specific activator (XylR) was then introduced into the phenylalanine-overproducing E. coli NST74, which relieved carbon catabolite repression and enabled efficient glucose-xylose co-utilization. Carbon contribution analysis through 13 C-fingerprinting showed a higher preference for xylose in the engineered strain (NST74X), suggesting superior catabolism of xylose relative to glucose. As a result, NST74X produced 1.76 g/L phenylalanine from a model glucose-xylose mixture; a threefold increase over NST74. Then, using biomass-derived sugars, NST74X produced 1.2 g/L phenylalanine, representing a 1.9-fold increase over NST74. Notably, and consistent with the carbon contribution analysis, the xylR* mutation resulted in a fourfold greater maximum rate of xylose consumption without significantly impeding the maximum rate of total sugar consumption (0.87 vs. 0.70 g/L-h). This study presents a novel strategy for enhancing phenylalanine production through the co-utilization of glucose and xylose in aerobic E. coli cultures, and highlights the potential synergistic benefits associated with using substrate mixtures over single substrates when targeting specific products.
Collapse
|
2
|
'Dark' CO 2 fixation in succinate fermentations enabled by direct CO 2 delivery via hollow fiber membrane carbonation. Bioprocess Biosyst Eng 2024; 47:223-233. [PMID: 38142425 DOI: 10.1007/s00449-023-02957-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 11/26/2023] [Indexed: 12/26/2023]
Abstract
Anaerobic succinate fermentations can achieve high-titer, high-yield performance while fixing CO2 through the reductive branch of the tricarboxylic acid cycle. To provide the needed CO2, conventional media is supplemented with significant (up to 60 g/L) bicarbonate (HCO3-), and/or carbonate (CO32-) salts. However, producing these salts from CO2 and natural ores is thermodynamically unfavorable and, thus, energetically costly, which reduces the overall sustainability of the process. Here, a series of composite hollow fiber membranes (HFMs) were first fabricated, after which comprehensive CO2 mass transfer measurements were performed under cell-free conditions using a novel, constant-pH method. Lumen pressure and total HFM surface area were found to be linearly correlated with the flux and volumetric rate of CO2 delivery, respectively. Novel HFM bioreactors were then constructed and used to comprehensively investigate the effects of modulating the CO2 delivery rate on succinate fermentations by engineered Escherichia coli. Through appropriate tuning of the design and operating conditions, it was ultimately possible to produce up to 64.5 g/L succinate at a glucose yield of 0.68 g/g; performance approaching that of control fermentations with directly added HCO3-/CO32- salts and on par with prior studies. HFMs were further found to demonstrate a high potential for repeated reuse. Overall, HFM-based CO2 delivery represents a viable alternative to the addition of HCO3-/CO32- salts to succinate fermentations, and likely other 'dark' CO2-fixing fermentations.
Collapse
|
3
|
Editorial overview: Energy biotechnology as an integral solution to global challenges. Curr Opin Biotechnol 2023; 84:103006. [PMID: 37793238 DOI: 10.1016/j.copbio.2023.103006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
|
4
|
Soluble and stable cyanophycin synthetase expression enhances heterologous cyanophycin production in Escherichia coli. Biochem Eng J 2023. [DOI: 10.1016/j.bej.2023.108916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2023]
|
5
|
Multi-omic based production strain improvement (MOBpsi) for bio-manufacturing of toxic chemicals. Metab Eng 2022; 72:133-149. [DOI: 10.1016/j.ymben.2022.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 02/11/2022] [Accepted: 03/08/2022] [Indexed: 11/25/2022]
|
6
|
Systematic Engineering of Synechococcus elongatus UTEX 2973 for Photosynthetic Production of l-Lysine, Cadaverine, and Glutarate. ACS Synth Biol 2021; 10:3561-3575. [PMID: 34851612 DOI: 10.1021/acssynbio.1c00492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amino acids and related targets are typically produced by well-characterized heterotrophs including Corynebacterium glutamicum and Escherichia coli. Cyanobacteria offer an opportunity to supplant these sugar-intensive processes by instead directly utilizing atmospheric CO2 and sunlight. Synechococcus elongatus UTEX 2973 (hereafter UTEX 2973) is a particularly promising photoautotrophic platform due to its fast growth rate. Here, we first engineered UTEX 2973 to overproduce l-lysine (hereafter lysine), after which both cadaverine and glutarate production were achieved through further pathway engineering. To facilitate metabolic engineering, the relative activities of a subset of previously uncharacterized promoters were investigated, in each case, while also comparing the effects of both chromosomal (from neutral site NS3) and episomal (from pAM4788) expressions. Using these parts, lysine overproduction in UTEX 2973 was engineered by introducing a feedback-resistant copy of aspartate kinase (encoded by lysCfbr) and a lysine exporter (encoded by ybjE), both from E. coli. While chromosomal expression resulted in lysine production up to just 325.3 ± 14.8 mg/L after 120 h, this was then increased to 556.3 ± 62.3 mg/L via plasmid-based expression, also surpassing prior reports of photoautotrophic lysine bioproduction. Lastly, additional products of interest were then targeted by modularly extending the lysine pathway to glutarate and cadaverine, two 5-carbon, bioplastic monomers. By this approach, glutarate has so far been produced at final titers reaching 67.5 ± 2.2 mg/L by 96 h, whereas cadaverine has been produced at up to 55.3 ± 6.7 mg/L. Overcoming pathway and/or transport bottlenecks, meanwhile, will be important to improving upon these initial outputs.
Collapse
|
7
|
Exploiting Polyploidy for Markerless and Plasmid-Free Genome Engineering in Cyanobacteria. ACS Synth Biol 2021; 10:2371-2382. [PMID: 34530614 DOI: 10.1021/acssynbio.1c00269] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Here we describe a universal approach for plasmid-free genome engineering in cyanobacteria that exploits the polyploidy of their chromosomes as a natural counterselection system. Rather than being delivered via replicating plasmids, genes encoding for DNA modifying enzymes are instead integrated into essential genes on the chromosome by allelic exchange, as facilitated by antibiotic selection, a process that occurs readily and with only minor fitness defects. By virtue of the essentiality of these integration sites, full segregation is never achieved, with the strain instead remaining as a merodiploid so long as antibiotic selection is maintained. As a result, once the desired genome modification is complete, removal of antibiotic selection results in the gene encoding for the DNA modifying enzyme to then be promptly eliminated from the population. Proof of concept of this new and generalizable strategy is provided using two different site-specific recombination systems, CRE-lox and DRE-rox, in the fast-growing cyanobacterium Synechococcus sp. PCC 7002, as well as CRE-lox in the model cyanobacterium Synechocystis sp. PCC 6803. Reusability of the method, meanwhile, is demonstrated by constructing a high-CO2 requiring and markerless Δndh3 Δndh4 ΔbicA ΔsbtA mutant of Synechococcus sp. PCC 7002. Overall, this method enables the simple and efficient construction of stable and unmarked mutants in cyanobacteria without the need to develop additional shuttle vectors nor counterselection systems.
Collapse
|
8
|
A coculture-coproduction system designed for enhanced carbon conservation through inter-strain CO 2 recycling. Metab Eng 2021; 67:387-395. [PMID: 34365009 DOI: 10.1016/j.ymben.2021.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/08/2021] [Accepted: 08/04/2021] [Indexed: 11/30/2022]
Abstract
Carbon loss in the form of CO2 is an intrinsic and persistent challenge faced during conventional and advanced biofuel production from biomass feedstocks. Current mechanisms for increasing carbon conservation typically require the provision of reduced co-substrates as additional reducing equivalents. This need can be circumvented, however, by exploiting the natural heterogeneity of lignocellulosic sugars mixtures and strategically using specific fractions to drive complementary CO2 emitting vs. CO2 fixing pathways. As a demonstration of concept, a coculture-coproduction system was developed by pairing two catabolically orthogonal Escherichia coli strains; one converting glucose to ethanol (G2E) and the other xylose to succinate (X2S). 13C-labeling studies reveled that G2E + X2S cocultures were capable of recycling 24% of all evolved CO2 and achieved a carbon conservation efficiency of 77%; significantly higher than the 64% achieved when all sugars are instead converted to just ethanol. In addition to CO2 exchange, the latent exchange of pyruvate between strains was discovered, along with significant carbon rearrangement within X2S.
Collapse
|
9
|
Optimization of a T7-RNA polymerase system in Synechococcus sp. PCC 7002 mirrors the protein overproduction phenotype from E. coli BL21(DE3). Appl Microbiol Biotechnol 2021; 105:1147-1158. [PMID: 33443634 DOI: 10.1007/s00253-020-11085-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/14/2020] [Accepted: 12/28/2020] [Indexed: 02/06/2023]
Abstract
With the goal of expanding the diversity of tools available for controlling gene expression in cyanobacteria, the T7-RNA polymerase gene expression system from E. coli BL21(DE3) was adapted and systematically engineered for robust function Synechococcus sp. PCC 7002, a fast-growing saltwater strain. Expression of T7-RNA polymerase was controlled via LacI regulation, while functionality was optimized by both further tuning its expression level along with optimizing the translation initiation region of the expressed gene, in this case an enhanced YFP reporter. Under high CO2 conditions, the resulting system displayed a 60-fold dynamic range in expression levels. Furthermore, when maximally induced, T7-RNA polymerase-dependent protein production constituted up to two-thirds of total cellular protein content in Synechococcus sp. PCC 7002. Ultimately, however, this came at the cost of 40% reductions in both biomass and pigmentation levels. Taken together, the developed T7-RNA polymerase gene expression system is effective for controlling and achieving high-level expression of heterologous genes in Synechococcus sp. PCC 7002, making it a valuable tool for cyanobacterial research. KEY POINTS: • Promoter driving T7-RNA polymerase was optimized. • Up to 60-fold dynamic range in expression, depending on CO2 conditions. • Two-thirds of total protein is T7-RNA polymerase dependent.
Collapse
|
10
|
Tetragonal crystal form of the cyanobacterial bicarbonate-transporter regulator SbtB from Synechocystis sp. PCC 6803. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2020; 76:438-443. [PMID: 32880592 DOI: 10.1107/s2053230x20010523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 07/31/2020] [Indexed: 11/10/2022]
Abstract
The PII-like protein SbtB has been identified as a regulator of SbtA, which is one of the key bicarbonate transporters in cyanobacteria. While SbtB from Synechocystis sp. PCC 6803 has previously been shown to be a trimer, a new crystal form is reported here which crystallizes in what is thought to be a non-native tetramer in the crystal, with the C-terminus in an extended conformation. The crystal structure shows the formation of an intermolecular disulfide bond at Cys94 between SbtB monomers, which may stabilize this conformation in the crystal. This motivates the need for future studies to investigate the potential role that the oxidation and reduction of these cysteines may play in the activation and/or function of SbtB.
Collapse
|
11
|
Heterologous expression and purification of the bicarbonate transporter BicA from Synechocystis sp. PCC 6803. Protein Expr Purif 2020; 175:105716. [PMID: 32738437 DOI: 10.1016/j.pep.2020.105716] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 06/25/2020] [Accepted: 07/22/2020] [Indexed: 11/18/2022]
Abstract
The high-flux/low-affinity cyanobacterial bicarbonate transporter BicA is a member of sulfate permease/solute carrier 26 (SulP/SLC26) family and plays a major role in cyanobacterial inorganic carbon uptake. In order to study this important membrane protein, robust platforms for over-expression and protocols for purification are required. In this work we have optimized the expression and purification of BicA from strain Synechocystis sp. PCC 6803 (BicA6803) in Escherichia coli. It was determined that expression with C43 (DE3) Rosetta2 at 37 °C produced the highest levels of over-expressed BicA6803 relative to other strains screened, and membrane solubilization with n-dodecyl-β-d-maltopyranoside facilitated the purification of high levels of stable and homogenous BicA6803. Using these expression and purification strategies, the final yields of purified BicA were 6.5 ± 1.0 mg per liter of culture.
Collapse
|
12
|
Catabolic Division of Labor Enhances Production of D-Lactate and Succinate From Glucose-Xylose Mixtures in Engineered Escherichia coli Co-culture Systems. Front Bioeng Biotechnol 2020; 8:329. [PMID: 32432089 PMCID: PMC7214542 DOI: 10.3389/fbioe.2020.00329] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 03/25/2020] [Indexed: 01/01/2023] Open
Abstract
Although biological upgrading of lignocellulosic sugars represents a promising and sustainable route to bioplastics, diverse and variable feedstock compositions (e.g., glucose from the cellulose fraction and xylose from the hemicellulose fraction) present several complex challenges. Specifically, sugar mixtures are often incompletely metabolized due to carbon catabolite repression while composition variability further complicates the optimization of co-utilization rates. Benefiting from several unique features including division of labor, increased metabolic diversity, and modularity, synthetic microbial communities represent a promising platform with the potential to address persistent bioconversion challenges. In this work, two unique and catabolically orthogonal Escherichia coli co-cultures systems were developed and used to enhance the production of D-lactate and succinate (two bioplastic monomers) from glucose-xylose mixtures (100 g L-1 total sugars, 2:1 by mass). In both cases, glucose specialist strains were engineered by deleting xylR (encoding the xylose-specific transcriptional activator, XylR) to disable xylose catabolism, whereas xylose specialist strains were engineered by deleting several key components involved with glucose transport and phosphorylation systems (i.e., ptsI, ptsG, galP, glk) while also increasing xylose utilization by introducing specific xylR mutations. Optimization of initial population ratios between complementary sugar specialists proved a key design variable for each pair of strains. In both cases, ∼91% utilization of total sugars was achieved in mineral salt media by simple batch fermentation. High product titer (88 g L-1 D-lactate, 84 g L-1 succinate) and maximum productivity (2.5 g L-1 h-1 D-lactate, 1.3 g L-1 h-1 succinate) and product yield (0.97 g g-total sugar-1 for D-lactate, 0.95 g g-total sugar-1 for succinate) were also achieved.
Collapse
|
13
|
Engineering a Synthetic, Catabolically Orthogonal Coculture System for Enhanced Conversion of Lignocellulose-Derived Sugars to Ethanol. ACS Synth Biol 2019; 8:1089-1099. [PMID: 30979337 DOI: 10.1021/acssynbio.9b00007] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Fermentation of lignocellulosic sugar mixtures is often suboptimal due to inefficient xylose catabolism and sequential sugar utilization caused by carbon catabolite repression. Unlike in conventional applications employing a single engineered strain, the alternative development of synthetic microbial communities facilitates the execution of complex metabolic tasks by exploiting the unique community features, including modularity, division of labor, and facile tunability. A series of synthetic, catabolically orthogonal coculture systems were systematically engineered, as derived from either wild-type Escherichia coli W or ethanologenic LY180. Net catabolic activities were effectively balanced by simple tuning of the inoculum ratio between specialist strains, which enabled coutilization (98% of 100 g L-1 total sugars) of glucose-xylose mixtures (2:1 by mass) for both culture systems in simple batch fermentations. The engineered ethanologenic cocultures achieved ethanol titer (46 g L-1), productivity (488 mg L-1 h-1), and yield (∼90% of theoretical maximum), which were all significantly increased compared to LY180 monocultures.
Collapse
|
14
|
Recent trends in integrated bioprocesses: aiding and expanding microbial biofuel/biochemical production. Curr Opin Biotechnol 2019; 57:82-87. [PMID: 30877994 DOI: 10.1016/j.copbio.2019.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 01/16/2019] [Accepted: 02/05/2019] [Indexed: 01/04/2023]
Abstract
Microbial biosynthesis of fuels and chemicals represents a promising route for their renewable production. Product toxicity, however, represents a common challenge limiting the efficacy of this approach. Integrated bioprocesses incorporating in situ product separation are poised to help address this intrinsic problem, but suffer their own unique shortcomings. To improve and expand the utility of this versatile bioprocessing strategy, recent innovations have focused on developing more effective separation materials and novel process configurations, as well as adapting designs to accommodate semi-continuous modes of operation. As a result, integrated bioprocesses are finding new applications to aid the biosynthesis of an ever-growing list of bioproducts. Emerging applications, meanwhile, are exploring the further expansion of such designs to interface microbial and chemical catalysts, leading to new and versatile routes for the one-pot synthesis of an even greater diversity of renewable products.
Collapse
|
15
|
Abstract
Muconic acid is a promising platform biochemical and precursor to adipic acid, which can be used to synthesize various plastics and polymers. In this study, the systematic construction and comparative evaluation of a modular network of non-natural pathways for muconic acid biosynthesis was investigated in Escherichia coli, including via three distinct and novel pathways proceeding via phenol as a common intermediate. However, poor recombinant activity and high promiscuity of phenol hydroxylase ultimately limited "phenol-dependent" muconic acid production. A fourth pathway proceeding via p-hydroxybenzoate, protocatechuate, and catechol was accordingly developed, though with muconic acid titers by this route reaching just 819 mg/L, its performance lagged behind that of the established, "3-dehydroshikimiate-derived" route. Finally, these two most promising pathways were coexpressed in parallel to create a synthetic "metabolic funnel" that, by enabling maximal net precursor assimilation and flux while preserving native chorismate biosynthesis, nearly doubled muconic acid production to up to >3.1 g/L at a glucose yield of 158 mg/g while introducing only a single auxotrophy. This generalizable, "funneling" strategy is expected to have broad applications in metabolic engineering for further enhancing production of muconic acid, as well as other important bioproducts of interest.
Collapse
|
16
|
Expanding Upon Styrene Biosynthesis to Engineer a Novel Route to 2‐Phenylethanol. Biotechnol J 2017; 12. [DOI: 10.1002/biot.201700310] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 08/07/2017] [Indexed: 11/07/2022]
|
17
|
Folate receptor-targeted aminoglycoside-derived polymers for transgene expression in cancer cells. Bioeng Transl Med 2016; 1:220-231. [PMID: 29313013 PMCID: PMC5675079 DOI: 10.1002/btm2.10038] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 09/02/2016] [Accepted: 09/13/2016] [Indexed: 12/25/2022] Open
Abstract
Targeted delivery of anticancer therapeutics can potentially overcome the limitations associated with current chemotherapeutic regimens. Folate receptors are overexpressed in several cancers, including ovarian, triple-negative breast and bladder cancers, making them attractive for targeted delivery of nucleic acid therapeutics to these tumors. This work describes the synthesis, characterization and evaluation of folic acid-conjugated, aminoglycoside-derived polymers for targeted delivery of transgenes to breast and bladder cancer cell lines. Transgene expression was significantly higher with FA-conjugated aminoglycoside-derived polymers than with Lipofectamine, and these polymers demonstrated minimal cytotoxicty. Competitive inhibition using free folic acid significantly reduced transgene expression efficacy of folate-targeted polymers, suggesting a role for folate receptor-mediated uptake. High efficacy FA-targeted polymers were employed to deliver a plasmid expressing the TRAIL protein, which induced death in cancer cells. These results indicate that FA-conjugated aminoglycoside-derived polymers are promising for targeted delivery of nucleic acids to cancer cells that overexpress folate receptors.
Collapse
|
18
|
Production of biorenewable styrene: utilization of biomass-derived sugars and insights into toxicity. ACTA ACUST UNITED AC 2016; 43:595-604. [DOI: 10.1007/s10295-016-1734-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 01/07/2016] [Indexed: 01/12/2023]
Abstract
Abstract
Fermentative production of styrene from glucose has been previously demonstrated in Escherichia coli. Here, we demonstrate the production of styrene from the sugars derived from lignocellulosic biomass depolymerized by fast pyrolysis. A previously engineered styrene-producing strain was further engineered for utilization of the anhydrosugar levoglucosan via expression of levoglucosan kinase. The resulting strain produced 240 ± 3 mg L−1 styrene from pure levoglucosan, similar to the 251 ± 3 mg L−1 produced from glucose. When provided at a concentration of 5 g L−1, pyrolytic sugars supported styrene production at titers similar to those from pure sugars, demonstrating the feasibility of producing this important industrial chemical from biomass-derived sugars. However, the toxicity of contaminant compounds in the biomass-derived sugars and styrene itself limit further gains in production. Styrene toxicity is generally believed to be due to membrane damage. Contrary to this prevailing wisdom, our quantitative assessment during challenge with up to 200 mg L−1 of exogenously provided styrene showed little change in membrane integrity; membrane disruption was observed only during styrene production. Membrane fluidity was also quantified during styrene production, but no changes were observed relative to the non-producing control strain. This observation that styrene production is much more damaging to the membrane integrity than challenge with exogenously supplied styrene provides insight into the mechanism of styrene toxicity and emphasizes the importance of verifying proposed toxicity mechanisms during production instead of relying upon results obtained during exogenous challenge.
Collapse
|
19
|
Engineering and comparison of non‐natural pathways for microbial phenol production. Biotechnol Bioeng 2016; 113:1745-54. [DOI: 10.1002/bit.25942] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 12/23/2015] [Accepted: 01/18/2016] [Indexed: 01/14/2023]
|
20
|
|
21
|
Engineering Escherichia coli for renewable benzyl alcohol production. Metab Eng Commun 2015; 2:39-45. [PMID: 34150507 PMCID: PMC8193235 DOI: 10.1016/j.meteno.2015.06.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 03/28/2015] [Accepted: 06/03/2015] [Indexed: 11/18/2022] Open
Abstract
Benzyl alcohol is an aromatic hydrocarbon used as a solvent and an intermediate chemical in the pharmaceutical, cosmetics, and flavor/fragrance industries. The de novo biosynthesis of benzyl alcohol directly from renewable glucose was herein explored using a non-natural pathway engineered in Escherichia coli. Benzaldehyde was first produced from endogenous phenylpyruvate via three heterologous steps, including hydroxymandelate synthase (encoded by hmaS) from Amycolatopsis orientalis, followed by (S)-mandelate dehydrogenase (encoded by mdlB) and phenylglyoxylate decarboxylase (encoded by mdlC) from Pseudomonas putida ATCC 12633. The subsequent rapid and efficient reduction of benzaldehyde to benzyl alcohol occurred by the combined activity and native regulation of multiple endogenous alcohol dehydrogenases and/or aldo-keto reductases. Through systematic deletion of competing aromatic amino acid biosynthesis pathways to promote endogenous phenylpyruvate availability, final benzyl alcohol titers as high as 114±1 mg/L were realized, representing a yield of 7.6±0.1 mg/g on glucose and a ~5-fold improvement over initial strains. A novel pathway to benzyl alcohol has been systematically engineered. Maximum titers reached 114±1 mg/L at a yield of 7.6±0.1 mg/g on glucose. Pathway flux limited by hydroxymandelate synthase, the first committed step. Product toxicity poorly represented by membrane accumulation/disruption model. The pathway can further serve as a platform for producing benzaldehyde.
Collapse
|
22
|
ACC/AHA/AACVPR/AAFP/ANA concepts for clinician-patient shared accountability in performance measures: a report of the American College of Cardiology/American Heart Association Task Force on Performance Measures. Circulation 2014; 130:1984-94. [PMID: 25366994 DOI: 10.1161/cir.0000000000000139] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
23
|
ACC/AHA/AACVPR/AAFP/ANA concepts for clinician-patient shared accountability in performance measures: a report of the American College of Cardiology/American Heart Association Task Force on Performance Measures. J Am Coll Cardiol 2014; 64:2133-45. [PMID: 25439761 DOI: 10.1016/j.jacc.2014.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
24
|
Rational engineering of a novel pathway for producing the aromatic compounds p-hydroxybenzoate, protocatechuate, and catechol in Escherichia coli. Process Biochem 2014. [DOI: 10.1016/j.procbio.2014.08.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
25
|
The Role of Otolaryngologists in the Accountable Care Organization: Pros and Cons. Otolaryngol Head Neck Surg 2014. [DOI: 10.1177/0194599814538403a7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Program Description: There are many questions about the role of otolaryngologists in an Affordable Care Organization (ACO). Our team of experts from private practice to academia, from administration to technology, will engage the audience. We will incorporate content that focuses on patient care, quality improvement, and access. We will welcome questions and advice from the audience. Educational Objectives: (1) Make an informed decision whether to join or not to join an ACO. (2) Recognize the pros and cons to such a decision. (3) Manage the risk involved in this decision.
Collapse
|
26
|
Synthetic biology applications in industrial microbiology. Front Microbiol 2014; 5:451. [PMID: 25206353 PMCID: PMC4143612 DOI: 10.3389/fmicb.2014.00451] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 08/11/2014] [Indexed: 11/13/2022] Open
|
27
|
Rational and combinatorial approaches to engineering styrene production by Saccharomyces cerevisiae. Microb Cell Fact 2014; 13:123. [PMID: 25162943 PMCID: PMC4145238 DOI: 10.1186/s12934-014-0123-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 08/14/2014] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Styrene is an important building-block petrochemical and monomer used to produce numerous plastics. Whereas styrene bioproduction by Escherichia coli was previously reported, the long-term potential of this approach will ultimately rely on the use of hosts with improved industrial phenotypes, such as the yeast Saccharomyces cerevisiae. RESULTS Classical metabolic evolution was first applied to isolate a mutant capable of phenylalanine over-production to 357 mg/L. Transcription analysis revealed up-regulation of several phenylalanine biosynthesis pathway genes including ARO3, encoding the bottleneck enzyme DAHP synthase. To catalyze the first pathway step, phenylalanine ammonia lyase encoded by PAL2 from A. thaliana was constitutively expressed from a high copy plasmid. The final pathway step, phenylacrylate decarboxylase, was catalyzed by the native FDC1. Expression of FDC1 was naturally induced by trans-cinnamate, the pathway intermediate and its substrate, at levels sufficient for ensuring flux through the pathway. Deletion of ARO10 to eliminate the competing Ehrlich pathway and expression of a feedback-resistant DAHP synthase encoded by ARO4K229L preserved and promoted the endogenous availability precursor phenylalanine, leading to improved pathway flux and styrene production. These systematic improvements allowed styrene titers to ultimately reach 29 mg/L at a glucose yield of 1.44 mg/g, a 60% improvement over the initial strain. CONCLUSIONS The potential of S. cerevisiae as a host for renewable styrene production has been demonstrated. Significant strain improvements, however, will ultimately be needed to achieve economical production levels.
Collapse
|
28
|
|
29
|
Comparing in situ removal strategies for improving styrene bioproduction. Bioprocess Biosyst Eng 2014; 38:165-74. [DOI: 10.1007/s00449-014-1255-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 07/06/2014] [Indexed: 01/23/2023]
|
30
|
'Hybrid' processing strategies for expanding and improving the synthesis of renewable bioproducts. Curr Opin Biotechnol 2014; 30:17-23. [PMID: 24794630 DOI: 10.1016/j.copbio.2014.04.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 03/31/2014] [Accepted: 04/02/2014] [Indexed: 12/20/2022]
Abstract
The versatile functionality of microbial biocatalysts offers a promising solution to the growing need to replace conventional, petroleum-derived fuels, chemicals, and materials with sustainable alternatives from renewable biomass. Whereas metabolic pathway engineering and strain optimization have greatly expanded the range of attainable bioproducts, it is by coupling microbial biosynthesis with traditional chemical conversions that the diversity of products that can ultimately be derived from biomass is truly beginning to reach its full potential. As will be the focus of this short review, such 'hybrid' strategies are now facilitating the generation of new and useful value-added bioproducts from renewable sources, the likes of which have previously been unattainable via biological routes alone.
Collapse
|
31
|
|
32
|
In situ butanol recovery fromClostridium acetobutylicumfermentations by expanded bed adsorption. Biotechnol Prog 2013; 30:68-78. [DOI: 10.1002/btpr.1841] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 11/18/2013] [Indexed: 01/19/2023]
|
33
|
|
34
|
Detailed Analysis on Selecting/Installing/Using an Otolaryngology Electronic Medical Record System. Otolaryngol Head Neck Surg 2013. [DOI: 10.1177/0194599813493390a3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Program Description: Otolaryngologists are now focusing on acquiring an electronic medical record (EMR) system, learning to use EMRs, and/or replacing those that are outdated and do not meet their needs. Panelists will analyze specifics. Educational Objectives: 1) Critique an EMR system on the basis of cost, usability, workflow, quality, support, and return on investment. 2) Comply with meaningful use criteria to receive incentive money.
Collapse
|
35
|
Microbial production of the aromatic building-blocks (S)-styrene oxide and (R)-1,2-phenylethanediol from renewable resources. Biotechnol J 2013; 8:1465-75. [DOI: 10.1002/biot.201300035] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 05/31/2013] [Accepted: 06/25/2013] [Indexed: 11/08/2022]
|
36
|
|
37
|
Engineering cyanobacteria for photosynthetic production of 3-hydroxybutyrate directly from CO2. Metab Eng 2013; 16:68-77. [DOI: 10.1016/j.ymben.2013.01.001] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Revised: 12/27/2012] [Accepted: 01/03/2013] [Indexed: 11/17/2022]
|
38
|
Abstract
In February 2013, the American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF) released its list of 5 recommendations of diagnostic and therapeutic interventions that physicians and patients should question, as part of the American Board of Internal Medicine (ABIM) Foundation's Choosing Wisely campaign. This commentary outlines the impetus for the AAO-HNSF to join the campaign, our list of 5 recommendations, how they were developed, and our future involvement with the campaign. The AAO-HNSF's 5 recommendations are (1) don't order a computed tomography (CT) scan of the head/brain for sudden hearing loss, (2) don't prescribe oral antibiotics for uncomplicated acute tympanostomy tube otorrhea, (3) don't prescribe oral antibiotics for uncomplicated acute external otitis, (4) don't routinely obtain radiographic imaging for patients who meet diagnostic criteria for uncomplicated acute rhinosinusitis, and (5) don't obtain CT or magnetic resonance imaging in patients with a primary complaint of hoarseness prior to examining the larynx.
Collapse
|
39
|
EngineeringEscherichia colifor renewable production of the 5-carbon polyamide building-blocks 5-aminovalerate and glutarate. Biotechnol Bioeng 2013; 110:1726-34. [DOI: 10.1002/bit.24828] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 12/01/2012] [Accepted: 12/18/2012] [Indexed: 11/11/2022]
|
40
|
Engineering microbial chemical factories to produce renewable "biomonomers". Front Microbiol 2012; 3:313. [PMID: 22969753 PMCID: PMC3430982 DOI: 10.3389/fmicb.2012.00313] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 08/08/2012] [Indexed: 12/28/2022] Open
Abstract
By applying metabolic engineering tools and strategies to engineer synthetic enzyme pathways, the number and diversity of commodity and specialty chemicals that can be derived directly from renewable feedstocks is rapidly and continually expanding. This of course includes a number of monomer building-block chemicals that can be used to produce replacements to many conventional plastic materials. This review aims to highlight numerous recent and important advancements in the microbial production of these so-called "biomonomers." Relative to naturally-occurring renewable bioplastics, biomonomers offer several important advantages, including improved control over the final polymer structure and purity, the ability to synthesize non-natural copolymers, and allowing products to be excreted from cells which ultimately streamlines downstream recovery and purification. To highlight these features, a handful of biomonomers have been selected as illustrative examples of recent works, including polyamide monomers, styrenic vinyls, hydroxyacids, and diols. Where appropriate, examples of their industrial penetration to date and end-product uses are also highlighted. Novel biomonomers such as these are ultimately paving the way toward new classes of renewable bioplastics that possess a broader diversity of properties than ever before possible.
Collapse
|
41
|
Electronic Health Records/Electronic Medical Records: Meaningful Use Update. Otolaryngol Head Neck Surg 2012. [DOI: 10.1177/0194599812449008a4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
42
|
Leadership View of PSQI. Otolaryngol Head Neck Surg 2012. [DOI: 10.1177/0194599812449008a11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
43
|
Abstract
In 2011, the US federal government implemented an oversight program to encourage the adoption and meaningful use of electronic health records (EHRs). Otolaryngologists may receive as much as $44,000 under Medicare or $63,750 under Medicaid as part of this law. To receive this full benefit, otolaryngologists must acquire a certified EHR and demonstrate stage 1 meaningful use requirements by the end of 2012. Furthermore, the Office of the National Coordinator for Health IT intends to advance meaningful use requirements to stage 2 (estimated to go in effect in 2014) and stage 3 requirements. This commentary discusses updated recommendations from the Academy of Otolaryngology—Head and Neck Surgery Medical Informatics Committee for implementing meaningful use of EHRs, receiving incentive payments, and preparing for potential stage 2 and stage 3 requirements.
Collapse
|
44
|
Sensitivity analysis of a proposed model mechanism for newly created glucose-6-oxidases. AIChE J 2011. [DOI: 10.1002/aic.12762] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
45
|
Styrene biosynthesis from glucose by engineered E. coli. Metab Eng 2011; 13:544-54. [DOI: 10.1016/j.ymben.2011.06.005] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 06/02/2011] [Accepted: 06/14/2011] [Indexed: 10/18/2022]
|
46
|
Lifelong Learning as Part of the Quality Improvement Process. Otolaryngol Head Neck Surg 2011. [DOI: 10.1177/0194599811415818a34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Program Description: Lifelong learning is a process that begins when one enters medical school. It continues throughout residency and practice. With a constantly evolving and changing knowledge base, it provides tools for a continual educational process for the clinician. Lifelong learning has been mandated as a core essential element of both professional training, as well as maintenance of professional standing. The field of continuing medical education has evolved to meet this demand. The tools and methodologies available to the practicing clinician in today’s environment are constantly changing. In the past decade or so we have seen a change from education products being enduring materials, such as textbooks and journals to online on demand materials. This evolution has been brought about by not only improved technology but by advances in the understanding of how we learn. This miniseminar will initiate with a concept of how lifelong learning fits into residency training. The role of this competency and how it is managed in residency will be discussed. The evolution of the ability to measure and the different measurement tools available will be presented. It will then move into CME materials that are currently available on the market. The commonest materials will be demonstrated and an understanding of how online educational activities can contribute to online learning will be shown. A discussion of the new rules of CME that are on the horizon and how they impact physician interaction with pharmaceutical manufacturing and the requirements for measurement of outcomes will be presented. Each of us is soon going to be required to identify practice gaps and then demonstrate how we have addressed them. Finally we will have to demonstrate how we have changed our practice with this knowledge. The miniseminar will end with a discussion on how lifelong learning fits into the maintenance of the Certification Program of the American Board of Otolaryngology. The role of online education and certification of competence will be demonstrated. Educational Objectives: 1) Learn how to better able relate to the historical and evolutionary change in lifelong learning. 2) Understand online learning materials and how to integrate this teaching into identifying practice gaps and then modifying those gaps to provide the best possible care.
Collapse
|
47
|
EHR/EMR and “Meaningful Use”: Efficient Strategies to Comply with Current and Future Mandates. Otolaryngol Head Neck Surg 2011. [DOI: 10.1177/0194599811415818a4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Program Description: This miniseminar will analyze and help academic as well as private practice doctors to comply with the current and future criteria of “Meaningful Use” efficiently without interrupting the “patient-doctor encounter.” Features of electronic health record that will help the doctor and the staff as well as pitfalls will be discussed. Time will be allocated for Q&A. Educational Objectives: 1) Understand “Meaningful Use” criteria. 2) Be able to select and use an EHR/EMR to receive “stimulus money.” 3) Understand Pay for Performance.
Collapse
|
48
|
Meaningful use of electronic health records in otolaryngology: recommendations from the American Academy of Otolaryngology--Head and Neck Surgery Medical Informatics Committee. Otolaryngol Head Neck Surg 2011; 144:135-41. [PMID: 21493407 DOI: 10.1177/0194599810393441] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Under the Health Information Technology for Economic and Clinical Health (HITECH) Act, passed as a part of the American Recovery and Reinvestment Act of 2009, the US Congress implemented new regulations to encourage the adoption of electronic health records (EHRs). The federal government will expend up to $27 billion in incentive payments to physicians and hospitals to increase adoption and implement "meaningful use" of EHRs. Otolaryngologists may receive as much as $44,000 under Medicare or $63,750 under Medicaid as part of this law. In July 2010, the US Department of Health and Human Services announced final rules to support "meaningful use." This commentary discusses recommendations from the American Academy of Otolaryngology--Head and Neck Surgery Medical Informatics Committee for implementing "meaningful use" of EHRs to improve safety, quality, and efficiency of patient care and receiving incentive payments as defined by these new regulations.
Collapse
|
49
|
Facial Soft-Tissue Fillers conference: Assessing the State of the Science. J Am Acad Dermatol 2011; 64:S66-85, S85.e1-136. [PMID: 21458679 DOI: 10.1016/j.jaad.2011.02.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Accepted: 11/05/2010] [Indexed: 12/19/2022]
|
50
|
A strategic approach for the design and operation of two-phase partitioning bioscrubbers for the treatment of volatile organic compounds. Biotechnol Prog 2010; 26:1777-86. [DOI: 10.1002/btpr.481] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|