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2.
J Appl Entomol ; 146(5): 648-658, 2022 Jun.
Article in English | MEDLINE | ID: mdl-36246040

ABSTRACT

A stable, synchronized colony of whitefly (Bemisia tabaci MEAM1 Gennadius) was established in a single ~30 cu.ft. reach-in incubator and supported on cabbage host plants which were grown in a 2 × 2' mesh cage without the need for a greenhouse or dedicated growth rooms. The colony maintenance, including cage cleaning and rotation of plants, was reduced to less than 10 h per week and executed by minimally experienced researchers. In our hands, this method was approximately 10-fold less expensive in personnel and materials than current typical implementations. A predator-prey model of whitefly colony maintenance that included whitefly proliferation and host plant health was developed to better understand and avoid colony collapse. This quantitative model can be applied to inform decisions such as inoculum planning and is a mathematical framework to assess insect control strategies. Extensive measurements of colony input and output (such as image analysis of leaf area and whitefly population size) were performed to define basic 'feedback control' parameters to gain reproducibility of this inherently unstable scaled-down whitefly colony. Quantitative transfer of ~100 whiteflies repeatedly produced more than 5000 adult whiteflies over a 6-week, two-generation period. Larger scale experimentation could be easily accommodated by transferring adult whiteflies from the maintenance colony with a low flow vacuum capture device. This approach to colony maintenance would be useful to programs that lack extensive plant growth room or greenhouse access and require a "clean" implementation that will not contaminate an axenic tissue culture laboratory.

3.
Front Plant Sci ; 13: 921970, 2022.
Article in English | MEDLINE | ID: mdl-35941940

ABSTRACT

Industrial hemp is a diploid (2n = 20), dioecious plant, and an essential source of various phytochemical productions. More than 540 phytochemicals have been described, some of which proved helpful in the remedial treatment of human diseases. Therefore, further study of hemp phytochemicals in medicine is highly anticipated. Previously, we developed the vacuum agroinfiltration method, which allows the transient gene expression in hemp tissues including female flowers, where cannabinoids are produced and accumulated. In this study, we attempted to alter the composition of total CBD and THC. The RT-PCR and sanger sequence identified eleven copies of the CBDAS gene, two copies of the THCAS gene, and one CBCAS gene. Binary vectors were constructed to overexpress the CBDAS gene and silence the THCAS gene via RNA interference. The Transcript level of the CBDAS gene was increased by more than 10 times than the plants used as a control, which led to a 54% higher total CBD content. The silencing of the THCAS gene led to downregulation of the THCAS gene, with an 80% reduction in transcript levels, and total THC content was reduced to 43% compared with mock plant. These results suggest that hemp vacuum infiltration is highly effective for metabolic engineering of cannabinoids in hemp.

4.
Antonie Van Leeuwenhoek ; 114(12): 2205-2217, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34661815

ABSTRACT

Pseudomonas aeruginosa strain SW1 is an aerobic, motile, Gram-negative, and rod-shaped bacterium isolated from degraded seaweeds. Based on the 16S rRNA gene sequence and MALDI TOF analysis, strain SW1 exhibits 100% similarity to P. aeruginosa DSM 50,071, its closest phylogenetic neighbor. The complete genome of strain SW1 consists of a single circular chromosome with 23,258,857 bp (G + C content of 66%), including 6734 protein-coding sequences, 8 rRNA, and 63 tRNA sequences. The genome of the P. aeruginosa SW1 contains at least 27 genes for the biosynthesis of alginate and other exopolysaccharide involved in biofilm formation. KAAS and GO analysis and functional annotation by COG and CAZymes are consistent with the biosynthesis of alginate. In addition, the presence of antimicrobial resistance, multi-efflux operon, and antibiotic inactivation genes indicate a pathogenic potential similar to strain DSM50071. The high-quality genome and associated annotation provide a starting point to exploit the potential for P. aeruginosa to produce alginate.


Subject(s)
Pseudomonas aeruginosa , Seaweed , Alginates , Phylogeny , Pseudomonas aeruginosa/genetics , RNA, Ribosomal, 16S
5.
Plant Environ Interact ; 2(1): 28-35, 2021 Feb.
Article in English | MEDLINE | ID: mdl-37283847

ABSTRACT

Membrane lipids serve as substrates for the generation of numerous signaling lipids when plants are exposed to environmental stresses, and jasmonic acid, an oxidized product of 18-carbon unsaturated fatty acids (e.g., linolenic acid), has been recognized as the essential signal in wound-induced gene expression. Yet, the contribution of individual membrane lipids in linolenic acid generation is ill-defined. In this work, we performed spatial lipidomic experiments to track lipid changes that occur locally at the sight of leaf injury to better understand the potential origin of linolenic and linoleic acids from individual membrane lipids. The central veins of tomato leaflets were crushed using surgical forceps, leaves were cryosectioned and analyzed by two orthogonal matrix-assisted laser desorption/ionization mass spectrometry imaging platforms for insight into lipid spatial distribution. Significant changes in lipid composition are only observed 30 min after wounding, while after 60 min lipidome homeostasis has been re-established. Phosphatidylcholines exhibit a variable pattern of spatial behavior in individual plants. Among lysolipids, lysophosphatidylcholines strongly co-localize with the injured zone of wounded leaflets, while, for example, lysophosphatidylglycerol (LPG) (16:1) accumulated preferentially toward the apex in the injured zone of wounded leaflets. In contrast, two other LPGs (LPG [18:3] and LPG [18:2]) are depleted in the injured zone. Our high-resolution co-localization imaging analyses suggest that linolenic acids are predominantly released from PCs with 16_18 fatty acid composition along the entire leaf, while it seems that in the apex zone PG (16:1_18:3) significantly contributes to the linolenic acid pool. These results also indicate distinct localization and/or substrate preferences of phospholipase isoforms in leaf tissue.

6.
Front Plant Sci ; 11: 580621, 2020.
Article in English | MEDLINE | ID: mdl-33363552

ABSTRACT

Industrial hemp (Cannabis sativa L.) is a diploid (2n = 20), dioecious plant that is grown for fiber, seed, and oil. Recently, there has been a renewed interest in this crop because of its panoply of cannabinoids, terpenes, and other phenolic compounds. Specifically, hemp contains terpenophenolic compounds such as cannabidiol (CBD) and cannabigerol (CBG), which act on cannabinoid receptors and positively regulate various human metabolic, immunological, and physiological functions. CBD and CBG have an effect on the cytokine metabolism, which has led to the examination of cannabinoids on the treatment of viral diseases, including COVID-19. Based on genomic, transcriptomic, and metabolomic studies, several synthetic pathways of hemp secondary metabolite production have been elucidated. Nevertheless, there are few reports on hemp metabolic engineering despite obvious impact on scientific and industrial sectors. In this article, recent status and current perspectives on hemp metabolic engineering are reviewed. Three distinct approaches to expedite phytochemical yield are discussed. Special emphasis has been placed on transgenic and transient gene delivery systems, which are critical for successful metabolic engineering of hemp. The advent of new tools in synthetic biology, particularly the CRISPR/Cas systems, enables environment-friendly metabolic engineering to increase the production of desirable hemp phytochemicals while eliminating the psychoactive compounds, such as tetrahydrocannabinol (THC).

7.
Int J Mol Sci ; 21(19)2020 Sep 30.
Article in English | MEDLINE | ID: mdl-33008056

ABSTRACT

Tomato mottle virus (ToMoV) is a single-stranded DNA (ssDNA) begomovirus transmitted to solanaceous crops by the whitefly species complex (Bemisia tabaci), causing stunted growth, leaf mottling, and reduced yield. Using a genetic repertoire of seven genes, ToMoV pathogenesis includes the manipulation of multiple plant biological processes to circumvent antiviral defenses. To further understand the effects of whitefly feeding and whitefly-transmitted ToMoV infection on tomato plants (Solanum lycopersicum 'Florida Lanai'), we generated comprehensive protein profiles of leaves subjected to feeding by either viruliferous whiteflies harboring ToMoV, or non-viruliferous whiteflies, or a no-feeding control. The effects of whitefly feeding and ToMoV infection were measured both locally and systemically by sampling either a mature leaf directly from the site of clip-cage confined whitefly feeding, or from a newly formed leaf 10 days post feeding (dpf). At 3 dpf, tomato's response to ToMoV included proteins associated with translation initiation and elongation as well as plasmodesmata dynamics. In contrast, systemic impacts of ToMoV on younger leaves 10 dpf were more pronounced and included a virus-specific change in plant proteins associated with mRNA maturation and export, RNA-dependent DNA methylation, and other antiviral plant processes. Our analysis supports previous findings and provides novel insight into tomato's local and systemic response to whitefly feeding and ToMoV infection.


Subject(s)
Begomovirus/pathogenicity , Plant Diseases/genetics , Plant Proteins/genetics , Solanum lycopersicum/genetics , Animals , Begomovirus/genetics , Hemiptera/genetics , Hemiptera/virology , Solanum lycopersicum/growth & development , Solanum lycopersicum/virology , Plant Diseases/virology , Plant Leaves/genetics , Plant Leaves/growth & development , Plant Leaves/virology , Plant Proteins/classification , Proteomics
8.
Int J Mol Sci ; 21(12)2020 Jun 23.
Article in English | MEDLINE | ID: mdl-32586033

ABSTRACT

Drought is the leading cause of agricultural yield loss among all abiotic stresses, and the link between water deficit and phloem protein contents is relatively unexplored. Here we collected phloem exudates from Solanum lycopersicum leaves during periods of drought stress and recovery. Our analysis identified 2558 proteins, the most abundant of which were previously localized to the phloem. Independent of drought, enrichment analysis of the total phloem exudate protein profiles from all samples suggests that the protein content of phloem sap is complex, and includes proteins that function in chaperone systems, branched-chain amino acid synthesis, trehalose metabolism, and RNA silencing. We observed 169 proteins whose abundance changed significantly within the phloem sap, either during drought or recovery. Proteins that became significantly more abundant during drought include members of lipid metabolism, chaperone-mediated protein folding, carboxylic acid metabolism, abscisic acid signaling, cytokinin biosynthesis, and amino acid metabolism. Conversely, proteins involved in lipid signaling, sphingolipid metabolism, cell wall organization, carbohydrate metabolism, and a mitogen-activated protein kinase are decreased during drought. Our experiment has achieved an in-depth profiling of phloem sap protein contents during drought stress and recovery that supports previous findings and provides new evidence that multiple biological processes are involved in drought adaptation.


Subject(s)
Adaptation, Physiological , Exudates and Transudates/metabolism , Phloem/metabolism , Plant Proteins/metabolism , Solanum lycopersicum/metabolism , Stress, Physiological , Droughts , Solanum lycopersicum/growth & development , Signal Transduction
9.
Biotechnol Lett ; 39(11): 1747-1755, 2017 Nov.
Article in English | MEDLINE | ID: mdl-28762033

ABSTRACT

OBJECTIVES: To carry out mass propagation of superior plants to improve agricultural and silvicultural production though advancements in plant cell totipotency, or the ability of differentiated somatic plant cells to regenerate an entire plant. RESULTS: The first demonstration of a titratable control over somatic embryo formation in a commercially relevant plant, Theobroma cacao (Chocolate tree), was achieved using a dexamethasone activatable chimeric transcription factor. This four-fold enhancement in embryo production rate utilized a glucocorticoid receptor fused to an embryogenic transcription factor LEAFY COTYLEDON 2. Where previous T. cacao somatic embryogenesis has been restricted to dissected flower parts, this construct confers an unprecedented embryogenic potential to leaves. CONCLUSIONS: Activatable chimeric transcription factors provide a means for elucidating the regulatory cascade associated with plant somatic embryogenesis towards improving its use for somatic regeneration of transgenics and plant propagation.


Subject(s)
Cacao/embryology , Dexamethasone/pharmacology , Receptors, Glucocorticoid/genetics , Transcription Factors/genetics , Cacao/drug effects , Enzyme Activation , Gene Expression Regulation, Developmental/drug effects , Gene Expression Regulation, Plant/drug effects , Plant Proteins/genetics , Plant Proteins/metabolism , Plant Somatic Embryogenesis Techniques , Plants, Genetically Modified , Receptors, Glucocorticoid/metabolism , Recombinant Fusion Proteins/metabolism , Transcription Factors/metabolism
10.
J Biosci Bioeng ; 122(6): 694-700, 2016 Dec.
Article in English | MEDLINE | ID: mdl-27323930

ABSTRACT

Metagenomics has the potential to facilitate the discovery of novel enzymes; however, to date, only a few alkaline proteases have been characterized from environmentally-sourced DNA. We report the identification and characterization of an alkaline serine protease designated as Prt1A from the metagenomic library of tannery activated sludge. Sequence analysis revealed that Prt1A is closely related to S8A family subtilisins with a catalytic triad of Asp143, His173, and Ser326. The putative protease gene (prt-1A) was subcloned in pET 28a (+) vector and overexpressed in Escherichia coli BL21(DE3)pLysS cells. This 38.8 KDa recombinant protease was purified to homogeneity by nickel affinity chromatography and exhibited optimal enzyme activity at elevated pH (11.0) and temperature (55°C). The enzyme activity was enhanced by the addition of 5 mM Ca2+ ions, and was stable in the presence of anionic detergent, oxidizing agent and various organic solvents. The enzyme displayed high affinity and catalytic efficiency for casein under standard assay conditions (Vmax = 279 U/mg/min, Km = 1.70 mg/mL) and was also compatible with commercial detergents. These results suggest that Prt1A protease could act as an efficient enzyme in various industrial applications.


Subject(s)
Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Endopeptidases/genetics , Endopeptidases/metabolism , Metagenomics , Sewage/microbiology , Textile Industry , Amino Acid Sequence , Cloning, Molecular , Enzyme Stability , Escherichia coli/enzymology , Escherichia coli/genetics , Escherichia coli/metabolism , Gene Expression Regulation, Enzymologic , Gene Library , Hydrogen-Ion Concentration , Temperature
11.
Biotechnol Prog ; 32(2): 337-45, 2016 03.
Article in English | MEDLINE | ID: mdl-26698639

ABSTRACT

Temporary immersion bioreactors (TIBs) are being used to propagate superior plant species on a commercial scale. We demonstrate a new TIB design, a Hydrostatic-driven TIB (Hy-TIB), where periodic raising and lowering the media reservoir maintains the advantages of temporary immersion of plant tissues without requiring large amounts of gas to move the media that is a characteristic of other TIB designs. The advantage of utilizing low volumes of gas mixtures (that are more expensive than air) is shown by a doubling of the growth rate of plant root cultures under elevated (40%) oxygen in air, and with CO2 supplementation showing improved phototrophic and photomixotrophic growth of seedless watermelon meristem cultures. The development of this bioreactor system involved overcoming contamination issues associated with utilizing very low gas flow rates and included utilizing microchip pressure sensors to diagnose unexpected changes in internal bioreactor pressure (± 20 Pa ∼0.0002 atm) caused by flexing of non-rigid plastic bag vessels. The overall design seeks to achieve versatility, scalability and minimum cost such that bioreactor technology can play an increasing role in the critical need to improve plant productivity in the face of increasing demand for food, reduced resources, and environmental degradation. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:337-345, 2016.


Subject(s)
Bioreactors , Carbon Dioxide/metabolism , Oxygen/metabolism , Plant Roots/metabolism , Carbon Dioxide/chemistry , Equipment Design , Oxygen/chemistry , Plant Roots/chemistry
12.
PLoS One ; 10(7): e0132441, 2015.
Article in English | MEDLINE | ID: mdl-26167854

ABSTRACT

A rapid, cost effective method of metagenomic DNA extraction from soil is a useful tool for environmental microbiology. The present work describes an improved method of DNA extraction namely "powdered glass method" from diverse soils. The method involves the use of sterile glass powder for cell lysis followed by addition of 1% powdered activated charcoal (PAC) as purifying agent to remove humic substances. The method yielded substantial DNA (5.87 ± 0.04 µg/g of soil) with high purity (A260/280: 1.76 ± 0.05) and reduced humic substances (A340: 0.047 ± 0.03). The quality of the extracted DNA was compared against five different methods based on 16S rDNA PCR amplification, BamHI digestion and validated using quantitative PCR. The digested DNA was used for a metagenomic library construction with the transformation efficiency of 4 X 106 CFU mL-1. Besides providing rapid, efficient and economical extraction of metgenomic DNA from diverse soils, this method's applicability is also demonstrated for cultivated organisms (Gram positive B. subtilis NRRL-B-201, Gram negative E. coli MTCC40, and a microalgae C. sorokiniana UTEX#1666).


Subject(s)
DNA, Bacterial/isolation & purification , Metagenomics/methods , Soil/chemistry , Cost-Benefit Analysis , DNA, Bacterial/genetics , Genomic Library , Humic Substances/analysis , Humic Substances/microbiology , Metagenomics/economics , Polymerase Chain Reaction/methods , RNA, Ribosomal, 16S/genetics , RNA, Ribosomal, 16S/isolation & purification , Soil Microbiology
13.
Appl Environ Microbiol ; 81(16): 5440-8, 2015 Aug 15.
Article in English | MEDLINE | ID: mdl-26048945

ABSTRACT

Novel processing strategies for hydrolysis and fermentation of lignocellulosic biomass in a single reactor offer large potential cost savings for production of biocommodities and biofuels. One critical challenge is retaining high enzyme production in the presence of elevated product titers. Toward this goal, the cellulolytic, ethanol-producing bacterium Clostridium phytofermentans was adapted to increased ethanol concentrations. The resulting ethanol-tolerant (ET) strain has nearly doubled ethanol tolerance relative to the wild-type level but also reduced ethanol yield and growth at low ethanol concentrations. The genome of the ET strain has coding changes in proteins involved in membrane biosynthesis, the Rnf complex, cation homeostasis, gene regulation, and ethanol production. In particular, purification of the mutant bifunctional acetaldehyde coenzyme A (CoA)/alcohol dehydrogenase showed that a G609D variant abolished its activities, including ethanol formation. Heterologous expression of Zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase in the ET strain increased cellulose consumption and restored ethanol production, demonstrating how metabolic engineering can be used to overcome disadvantageous mutations incurred during adaptation to ethanol. We discuss how genetic changes in the ET strain reveal novel potential strategies for improving microbial solvent tolerance.


Subject(s)
Cellulose/metabolism , Clostridium/genetics , Clostridium/metabolism , Ethanol/metabolism , Metabolic Engineering , Metabolic Networks and Pathways/genetics , Adaptation, Biological , Alcohol Dehydrogenase/genetics , Alcohol Dehydrogenase/metabolism , Drug Tolerance , Ethanol/toxicity , Gene Expression , Pyruvate Decarboxylase/genetics , Pyruvate Decarboxylase/metabolism , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Zymomonas/enzymology , Zymomonas/genetics
14.
Metab Eng ; 30: 105-120, 2015 Jul.
Article in English | MEDLINE | ID: mdl-25959019

ABSTRACT

The ability of autotrophic organisms to fix CO2 presents an opportunity to utilize this 'greenhouse gas' as an inexpensive substrate for biochemical production. Unlike conventional heterotrophic microorganisms that consume carbohydrates and amino acids, prokaryotic chemolithoautotrophs have evolved the capacity to utilize reduced chemical compounds to fix CO2 and drive metabolic processes. The use of chemolithoautotrophic hosts as production platforms has been renewed by the prospect of metabolically engineered commodity chemicals and fuels. Efforts such as the ARPA-E electrofuels program highlight both the potential and obstacles that chemolithoautotrophic biosynthetic platforms provide. This review surveys the numerous advances that have been made in chemolithoautotrophic metabolic engineering with a focus on hydrogen oxidizing bacteria such as the model chemolithoautotrophic organism (Ralstonia), the purple photosynthetic bacteria (Rhodobacter), and anaerobic acetogens. Two alternative strategies of microbial chassis development are considered: (1) introducing or enhancing autotrophic capabilities (carbon fixation, hydrogen utilization) in model heterotrophic organisms, or (2) improving tools for pathway engineering (transformation methods, promoters, vectors etc.) in native autotrophic organisms. Unique characteristics of autotrophic growth as they relate to bioreactor design and process development are also discussed in the context of challenges and opportunities for genetic manipulation of organisms as production platforms.


Subject(s)
Biofuels , Metabolic Engineering/methods , Ralstonia , Rhodobacter , Ralstonia/genetics , Ralstonia/metabolism , Rhodobacter/genetics , Rhodobacter/metabolism
15.
Protein Expr Purif ; 115: 109-17, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26008117

ABSTRACT

Membrane protein overexpression is often hindered by toxic effects on the expression host, limiting achievable volumetric productivity. Moreover, protein structure and function may be impaired due to inclusion body formation and proteolytic degradation. To address these challenges, we employed the photosynthetic bacterium, Rhodobacter sphaeroides for expression of challenging membrane proteins including human aquaporin 9 (hAQP9), human tight junction protein occludin (Occ), Escherichia coli toxin peptide GhoT, cellulose synthase enzyme complex (BcsAB) of R. sphaeroides and cytochrome-cy (Cyt-cy) from Rhodobacter capsulatus. Titers of 47 mg/L for Cyt-cy, 7.5 mg/L for Occ, 1.5 mg/L for BcsAB and 0.5 mg/L for hAQP9 were achieved from affinity purification. While purification of GhoT was not successful, transformants displayed a distinct growth phenotype that correlated with GhoT expression. We also evaluated the functionality of these proteins by performing water transport studies for hAQP9, peroxidase activity for cytochrome-cy, and in vitro cellulose synthesis activity assay for BcsAB. While previous studies with Rhodobacter have utilized oxygen-limited semi-aerobic growth for membrane protein expression, substantial titer improvements are achieved as a result of a 3-fold increase in biomass yield using the anaerobic photoheterotrophic growth regime, which utilizes the strong native puc promoter. This versatile platform is shown to enable recovery of a wide variety of difficult-to-express membrane proteins in functional form.


Subject(s)
Biotechnology/methods , Membrane Proteins/metabolism , Recombinant Proteins/metabolism , Rhodobacter sphaeroides/genetics , Humans , Membrane Proteins/chemistry , Membrane Proteins/genetics , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Rhodobacter sphaeroides/metabolism
16.
BMC Plant Biol ; 15: 121, 2015 May 16.
Article in English | MEDLINE | ID: mdl-25976599

ABSTRACT

BACKGROUND: Theobroma cacao, the chocolate tree, is an important economic crop in East Africa, South East Asia, and South and Central America. Propagation of elite varieties has been achieved through somatic embryogenesis (SE) but low efficiencies and genotype dependence still presents a significant limitation for its propagation at commercial scales. Manipulation of transcription factors has been used to enhance the formation of SEs in several other plant species. This work describes the use of the transcription factor Baby Boom (BBM) to promote the transition of somatic cacao cells from the vegetative to embryonic state. RESULTS: An ortholog of the Arabidopsis thaliana BBM gene (AtBBM) was characterized in T. cacao (TcBBM). TcBBM expression was observed throughout embryo development and was expressed at higher levels during SE as compared to zygotic embryogenesis (ZE). TcBBM overexpression in A. thaliana and T. cacao led to phenotypes associated with SE that did not require exogenous hormones. While transient ectopic expression of TcBBM provided only moderate enhancements in embryogenic potential, constitutive overexpression dramatically increased SE proliferation but also appeared to inhibit subsequent development. CONCLUSION: Our work provides validation that TcBBM is an ortholog to AtBBM and has a specific role in both somatic and zygotic embryogenesis. Furthermore, our studies revealed that TcBBM transcript levels could serve as a biomarker for embryogenesis in cacao tissue. Results from transient expression of TcBBM provide confirmation that transcription factors can be used to enhance SE without compromising plant development and avoiding GMO plant production. This strategy could compliment a hormone-based method of reprogramming somatic cells and lead to more precise manipulation of SE at the regulatory level of transcription factors. The technology would benefit the propagation of elite varieties with low regeneration potential as well as the production of transgenic plants, which similarly requires somatic cell reprogramming.


Subject(s)
Cacao/embryology , Plant Proteins/metabolism , Plant Somatic Embryogenesis Techniques/methods , Sequence Homology, Amino Acid , Transcription Factors/metabolism , Amino Acid Sequence , Arabidopsis/drug effects , Arabidopsis/genetics , Cacao/drug effects , Cacao/genetics , Cotyledon/drug effects , Cotyledon/growth & development , Gene Expression Regulation, Developmental/drug effects , Gene Expression Regulation, Plant/drug effects , Molecular Sequence Data , Phylogeny , Plant Growth Regulators/pharmacology , Plants, Genetically Modified , Seeds/drug effects , Seeds/embryology , Seeds/genetics
17.
Biotechnol Bioeng ; 112(8): 1523-32, 2015 Aug.
Article in English | MEDLINE | ID: mdl-25728701

ABSTRACT

Triterpene hydrocarbon biosynthesis of the ancient algae Botryococcus braunii was installed into Rhodobacter capsulatus to explore the production of C30 hydrocarbon in a host capable of diverse growth habits-utilizing carbohydrate, sunlight or hydrogen (with CO2 fixation) as alternative energy feedstocks. Engineering an enhanced MEP pathway was also used to augment triterpene accumulation. Despite dramatically different sources of carbon and reducing power, nearly the same level of botryococcene or squalene (∼5 mg oil/g-dry-weight [gDW]) was achieved in small-scale aerobic heterotrophic, anaerobic photoheterotrophic, and aerobic chemoautotrophic growth conditions. A glucose fed-batch bioreactor reached 40 mg botryococcene/L (∼12 mg/gDW), while autotrophic bioreactor performance with CO2 , H2 , and O2 reached 110 mg/L (16.7 mg/gDW) during batch and 60 mg/L (23 mg/gDW) during continuous operation at a dilution rate corresponding to about 10% of µ(max). Batch and continuous autotrophic specific productivity was found to reach 0.5 and 0.32 mg triterpene/g DW/h, comparable to prior reports for terpene production driven by heterotrophic growth conditions. This demonstrates the feasibility of alternative feedstocks and trophic modes to provide comparable routes to biochemicals that do not rely on sugar.


Subject(s)
Genetic Engineering/methods , Metabolic Networks and Pathways/genetics , Rhodobacter capsulatus/genetics , Rhodobacter capsulatus/metabolism , Triterpenes/metabolism , Aerobiosis , Anaerobiosis , Bioreactors/microbiology , Carbohydrate Metabolism , Chlorophyta/genetics , Energy Metabolism , Hydrogen/metabolism , Photosynthesis
18.
Bioresour Technol ; 172: 201-211, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25262429

ABSTRACT

Economic analysis of an ARPA-e Electrofuels (http://arpa-e.energy.gov/?q=arpa-e-programs/electrofuels) process is presented, utilizing metabolically engineered Rhodobacter capsulatus or Ralstonia eutropha to produce the C30+ hydrocarbon fuel, botryococcene, from hydrogen, carbon dioxide, and oxygen. The analysis is based on an Aspen plus® bioreactor model taking into account experimentally determined Rba. capsulatus and Rls. eutropha growth and maintenance requirements, reactor residence time, correlations for gas-liquid mass-transfer coefficient, gas composition, and specific cellular fuel productivity. Based on reactor simulation results encompassing technically relevant parameter ranges, the capital and operating costs of the process were estimated for 5000 bbl-fuel/day plant and used to predict fuel cost. Under the assumptions used in this analysis and crude oil prices, the Levelized Cost of Electricity (LCOE) required for economic feasibility must be less than 2¢/kWh. While not feasible under current market prices and costs, this work identifies key variables impacting process cost and discusses potential alternative paths toward economic feasibility.


Subject(s)
Biofuels/economics , Chemoautotrophic Growth , Cupriavidus necator/metabolism , Rhodobacter capsulatus/metabolism , Triterpenes/metabolism , Bioreactors , Models, Economic
19.
Microbiology (Reading) ; 160(Pt 6): 1134-1143, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24625451

ABSTRACT

Biofilm formation is a critical component to the lifestyle of many naturally occurring cellulose-degrading microbes. In this work, cellular aggregation and biofilm formation of Clostridium phytofermentans, a cellulolytic anaerobic bacterium, was investigated using a combination of microscopy and analytical techniques. Aggregates included thread-like linkages and a DNA/protein-rich extracellular matrix when grown on soluble cellobiose. Similar dense biofilms formed on the surface of the model cellulosic substrate Whatman no. 1 filter paper. Following initially dispersed attachment, microcolonies of ~500 µm diameter formed on the filter paper after 6 days. Enzymic treatment of both the biofilm and cellular aggregates with DNase and proteinase resulted in significant loss of rigidity, pointing to the key role of extracellular DNA and proteins in the biofilm structure. A high-throughput biofilm assay was adapted for studying potential regulators of biofilm formation. Various media manipulations were shown to greatly impact biofilm formation, including repression in the presence of glucose but not the ß(1→4)-linked disaccharide cellobiose, implicating a balance of hydrolytic activity and assimilation to maintain biofilm integrity. Using the microtitre plate biofilm assay, DNase and proteinase dispersed ~60 and 30 % of mature biofilms, respectively, whilst RNase had no impact. This work suggests that Clostridium phytofermentans has evolved a DNA/protein-rich biofilm matrix complementing its cellulolytic nature. These insights add to our current understanding of natural ecosystems as well as strategies for efficient bioprocess design.


Subject(s)
Bacterial Adhesion , Biofilms/growth & development , Clostridium/physiology , DNA, Bacterial/metabolism , Cellulose/metabolism , Deoxyribonucleases/metabolism , Peptide Hydrolases/metabolism
20.
PLoS One ; 9(1): e86830, 2014.
Article in English | MEDLINE | ID: mdl-24497982

ABSTRACT

Aquaporins are highly selective water channel proteins integrated into plasma membranes of single cell organisms; plant roots and stromae; eye lenses, renal and red blood cells in vertebrates. To date, only a few microbial aquaporins have been characterized and their physiological importance is not well understood. Here we report on the cloning, expression and characterization of a novel aquaporin, RsAqpZ, from a purple photosynthetic bacterium, Rhodobacter sphaeroides ATCC 17023. The protein was expressed homologously at a high yield (∼20 mg/L culture) under anaerobic photoheterotrophic growth conditions. Stopped-flow light scattering experiments demonstrated its high water permeability (0.17±0.05 cm/s) and low energy of activation for water transport (2.93±0.60 kcal/mol) in reconstituted proteoliposomes at a protein to lipid ratio (w/w) of 0.04. We developed a fluorescence correlation spectroscopy based technique and utilized a fluorescent protein fusion of RsAqpZ, to estimate the single channel water permeability of RsAqpZ as 1.24 (±0.41) x 10(-12) cm(3)/s or 4.17 (±1.38)×10(10) H2O molecules/s, which is among the highest single channel permeability reported for aquaporins. Towards application to water purification technologies, we also demonstrated functional incorporation of RsAqpZ in amphiphilic block copolymer membranes.


Subject(s)
Aquaporins/metabolism , Bacterial Proteins/metabolism , Recombinant Proteins/metabolism , Rhodobacter sphaeroides/metabolism , Algorithms , Amino Acid Sequence , Aquaporins/classification , Aquaporins/genetics , Bacterial Proteins/genetics , Biological Transport , Blotting, Western , Cell Membrane Permeability , Cloning, Molecular , Gene Expression Regulation, Bacterial , Liposomes/metabolism , Liposomes/ultrastructure , Luminescent Proteins/genetics , Luminescent Proteins/metabolism , Microscopy, Electron , Models, Biological , Molecular Sequence Data , Phylogeny , Rhodobacter sphaeroides/genetics , Sequence Homology, Amino Acid , Water/metabolism
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