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Costa EN, Fernandes MG, Reis LC, Foresti AC, Martins LO, Scalon SPQ. Effects of previous infestation with Bemisia tabaci MEAM1 on the resistance to Chrysodeixis includens in Bt and non-Bt soybean plants. BRAZ J BIOL 2023; 83:e277899. [PMID: 38126646 DOI: 10.1590/1519-6984.277899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 11/28/2023] [Indexed: 12/23/2023] Open
Abstract
Transgenic Bt soybean plants have been developed to control insect pests, such as Anticarsia gemmatalis and Chrysodeixis includens. This objective has been achieved successfully; however, recently, some authors claimed that Bt soybean plants have been more susceptible than non-Bt soybean to Bemisia tabaci MEAM1. In addition, it is unknown whether Bt soybean plants infested by B. tabaci become less resistant to target pests. Therefore, this study aimed to evaluate: (i) whether the previous infestation with B. tabaci can compromise Bt and non-Bt soybean resistance to C. includens; (ii) the effects of B. tabaci infestations on Bt and non-Bt soybean plant growth; and (iii) whether B. tabaci feeding reduces contents of chlorophyll and carotenoids of soybean plants. Bt and non-Bt soybean plants pre-infested with B. tabaci showed no changes in resistance to C. includens. Bt soybean plants infested with B. tabaci showed a lower plant height than uninfested plants. Differently, non-Bt soybean plants exhibited no reduction in plant growth due to B. tabaci feeding. Bt soybean plants suffered a reduction in dry matter only under double infestation (B. tabaci and C. includens), while non-Bt soybean plants experienced reduction in dry matter when infested with B. tabaci and C. includens or by C. includens only. B. tabaci feeding did not alter contents of chlorophyll and carotenoids, and perhaps the reduction in plant growth was related to salivary toxins. Concluding, both Bt and non-Bt soybean plants were susceptible to B. tabaci feeding, evidencing necessity of developing soybean cultivars resistant to B. tabaci.
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Affiliation(s)
- E N Costa
- Universidade Federal da Grande Dourados - UFGD, Faculdade de Ciências Agrárias, Programa de Pós-graduação em Agronomia, Laboratório de Monitoramento de Insetos, Dourados, MS, Brasil
- Universidade Federal da Grande Dourados - UFGD, Faculdade de Ciências Biológicas e Ambientais, Programa de Pós-Graduação em Entomologia e Conservação da Biodiversidade, Laboratório de Monitoramento de Insetos, Dourados, MS, Brasil
| | - M G Fernandes
- Universidade Federal da Grande Dourados - UFGD, Faculdade de Ciências Agrárias, Programa de Pós-graduação em Agronomia, Laboratório de Monitoramento de Insetos, Dourados, MS, Brasil
- Universidade Federal da Grande Dourados - UFGD, Faculdade de Ciências Biológicas e Ambientais, Programa de Pós-Graduação em Entomologia e Conservação da Biodiversidade, Laboratório de Monitoramento de Insetos, Dourados, MS, Brasil
| | - L C Reis
- Universidade Federal da Grande Dourados - UFGD, Faculdade de Ciências Agrárias, Programa de Pós-graduação em Agronomia, Laboratório de Fisiologia Vegetal, Dourados, MS, Brasil
| | - A C Foresti
- Universidade Federal da Grande Dourados - UFGD, Faculdade de Ciências Agrárias, Programa de Pós-graduação em Agronomia, Laboratório de Fisiologia Vegetal, Dourados, MS, Brasil
| | - L O Martins
- Universidade Federal da Grande Dourados - UFGD, Faculdade de Ciências Biológicas e Ambientais, Programa de Pós-Graduação em Entomologia e Conservação da Biodiversidade, Laboratório de Monitoramento de Insetos, Dourados, MS, Brasil
| | - S P Q Scalon
- Universidade Federal da Grande Dourados - UFGD, Faculdade de Ciências Agrárias, Programa de Pós-graduação em Agronomia, Laboratório de Fisiologia Vegetal, Dourados, MS, Brasil
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2
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Delprat N, Martins LO, Blum LJ, Aymard CMG, Leca-Bouvier B, Octobre G, Doumèche B. User-friendly one-step disposable signal-on bioassay for glyphosate detection in water samples. Biosens Bioelectron 2023; 241:115689. [PMID: 37716158 DOI: 10.1016/j.bios.2023.115689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/30/2023] [Accepted: 09/10/2023] [Indexed: 09/18/2023]
Abstract
The onsite detection of glyphosate requires an easy-to-handle, low-cost and disposable assay for untrained users as requested by the ASSURED guidelines. A new strategy based on the expression of fusion proteins is proposed here. A glyphosate oxidase derived from Bacillus subtilis and the 6E10 variant of the dye peroxidase from Pseudomonas putida, both fused with the carbohydrate binding module (CBM) 3a from Clostridium thermocellum, were designed and expressed, leading to GlyphOx-CBM and 6E10-CBM. Cell lysates were used to immobilise both enzymes on cotton buds' heads without any purification. The cotton buds exhibit glyphosate oxidase activity when dipped into a glyphosate-contaminated water sample containing the 6E10-CBM chromogenic substrates. The chromophore could be quantified both in the solution and on the cotton buds' heads. Photography followed by image analysis allows to detect glyphosate with a linear range of 0.25-2.5 mM and a limit of detection (LoD) of 0.12 mM. When the chromogenic substrates are replaced by luminol, the chemiluminescence reaction allows the detection of glyphosate with a linear range of 2-500 μM and a LoD of 0.45 μM. No interference was observed using glyphosate analogues (glycine, sarcosine, aminomethylphosphonic acid) or other herbicides used in a mixture. Only cysteine was found to inhibit 6E10-CBM. Two river waters spiked with glyphosate lead to recoveries of 64-131%. This work describes a very easy-to-handle and inexpensive signal-on bioassay for glyphosate detection in real surface water samples.
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Affiliation(s)
- N Delprat
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ICBMS, UMR, 5246, 69622, Villeurbanne, France.
| | - L O Martins
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
| | - L J Blum
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ICBMS, UMR, 5246, 69622, Villeurbanne, France.
| | - C M G Aymard
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ICBMS, UMR, 5246, 69622, Villeurbanne, France.
| | - B Leca-Bouvier
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ICBMS, UMR, 5246, 69622, Villeurbanne, France.
| | - G Octobre
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ICBMS, UMR, 5246, 69622, Villeurbanne, France.
| | - B Doumèche
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ICBMS, UMR, 5246, 69622, Villeurbanne, France.
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Mendes S, Catarino T, Silveira C, Todorovic S, Martins LO. The catalytic mechanism of A-type dye-decolourising peroxidase BsDyP: neither aspartate nor arginine is individually essential for peroxidase activity. Catal Sci Technol 2015. [DOI: 10.1039/c5cy00478k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BsDyP from Bacillus subtilis belongs to the new dye-decolourising peroxidase (DyP) family. Here, we use transient kinetics to provide details on the catalytic cycle of BsDyP.
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Affiliation(s)
- S. Mendes
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Portugal
| | - T. Catarino
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Portugal
- Departamento de Química
- Faculdade de Ciências e Tecnologia
| | - C. Silveira
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Portugal
| | - S. Todorovic
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Portugal
| | - L. O. Martins
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Portugal
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Abstract
We examined the accumulation of organic solutes under optimum growth conditions in 12 species of thermophilic and hyperthermophilic Archaea belonging to the Crenarchaeota and Euryarchaeota. Pyrobaculum aerophilum, Thermoproteus tenax, Thermoplasma acidophilum, and members of the order Sulfolobales accumulated trehalose. Pyrococcus furiosus accumulated di-myo-inositol-1,1(prm1)(3,3(prm1))-phosphate and (beta)-mannosylglycerate, Methanothermus fervidus accumulated cyclic-2,3-bisphosphoglycerate and (beta)-mannosylglycerate, while the only solute detected in Pyrodictium occultum was di-myo-inositol-1,1(prm1)(3,3(prm1))-phosphate. Methanopyrus kandleri accumulated large concentrations of cyclic-2,3-bisphosphoglycerate. On the other hand, Archaeoglobus fulgidus accumulated three phosphorylated solutes; prominent among them was a compound identified as di-glycerol-phosphate. This solute increased in concentration as the salinity of the medium and the growth temperature were raised, suggesting that this compound serves as a general stress solute. Di-myo-inositol-1,1(prm1)(3,3(prm1))-phosphate accumulated at supraoptimal temperature only. The relationship between the accumulation of unusual solutes and high temperatures is also discussed.
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Enguita FJ, Marçal D, Martins LO, Grenha R, Bento I, Gato G, Lindley PF, Carrondo MA. Substrate and dioxygen binding to an endospore coat laccase from Bacillus subtilis. Acta Crystallogr A 2004. [DOI: 10.1107/s0108767304096813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
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Melo EP, Faria TQ, Martins LO, Gonçalves AM, Cabral JM. Cutinase unfolding and stabilization by trehalose and mannosylglycerate. Proteins 2001; 42:542-52. [PMID: 11170208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
The unfolding of cutinase at pH 4.5 was induced by increasing the temperature and guanidine hydrochloride concentration in the presence of potassium chloride, trehalose, and mannosylglycerate potassium salt. Protein thermal unfolding approached a two-state process, since the unfolding transitions were coincident within experimental error when assessed by near-ultraviolet (UV) difference, tryptophyl, and 8-anilino-1-naphthalene sulfonic acid (ANS) fluorescence spectroscopy. Trehalose at 0.5 M increased the temperature at which 50% of cutinase is unfolded by 3 degrees C. Unfolding induced by guanidine hydrochloride is clearly a non-two-state process. The presence of a stable intermediate was detected because unfolding assessed by near-UV difference spectroscopy occurs earlier than unfolding assessed by tryptophyl fluorescence. The intermediate is molten globule in character: the ANS fluorescence is higher than in the presence of the folded or unfolded state, showing native-like secondary structure and losing many tertiary interactions of the folded state, i.e., those surrounding the tyrosyl microenvironment. The stabilization effect of trehalose and mannosylglycerate was quantified by fitting the unfolding transitions to a model proposed by Staniforth et al. (Biochemistry 1993;32:3842-3851). This model takes into consideration the increase in solvation energies of the amino acid side-chains as the denaturant concentration was increased and the fraction of amino acid side-chains that become exposed in the unfolded structure of cutinase. Trehalose and mannosylglycerate stabilize the folded state relative to the intermediate by 1.4-1.6 and 1.6 kcal/mol and the intermediate relative to the unfolded state by 1.0 and 1.5 kcal/mol, respectively.
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Affiliation(s)
- E P Melo
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
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Martins LO, Empadinhas N, Marugg JD, Miguel C, Ferreira C, da Costa MS, Santos H. Biosynthesis of mannosylglycerate in the thermophilic bacterium Rhodothermus marinus. Biochemical and genetic characterization of a mannosylglycerate synthase. J Biol Chem 1999; 274:35407-14. [PMID: 10585410 DOI: 10.1074/jbc.274.50.35407] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biosynthetic reaction scheme for the compatible solute mannosylglycerate in Rhodothermus marinus is proposed based on measurements of the relevant enzymatic activities in cell-free extracts and in vivo (13)C labeling experiments. The synthesis of mannosylglycerate proceeded via two alternative pathways; in one of them, GDP mannose was condensed with D-glycerate to produce mannosylglycerate in a single reaction catalyzed by mannosylglycerate synthase, in the other pathway, a mannosyl-3-phosphoglycerate synthase catalyzed the conversion of GDP mannose and D-3-phosphoglycerate into a phosphorylated intermediate, which was subsequently converted to mannosylglycerate by the action of a phosphatase. The enzyme activities committed to the synthesis of mannosylglycerate were not influenced by the NaCl concentration in the growth medium. However, the combined mannosyl-3-phosphoglycerate synthase/phosphatase system required the addition of NaCl or KCl to the assay mixture for optimal activity. The mannosylglycerate synthase enzyme was purified and characterized. Based on partial sequence information, the corresponding mgs gene was identified from a genomic library of R. marinus. In addition, the mgs gene was overexpressed in Escherichia coli with a high yield. The enzyme had a molecular mass of 46,125 Da, and was specific for GDP mannose and D-glycerate. This is the first report of the characterization of a mannosylglycerate synthase.
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Affiliation(s)
- L O Martins
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Rua da Quinta Grande 6, Apartado 127, 2780 Oeiras, Portugal
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Silva Z, Borges N, Martins LO, Wait R, da Costa MS, Santos H. Combined effect of the growth temperature and salinity of the medium on the accumulation of compatible solutes by Rhodothermus marinus and Rhodothermus obamensis. Extremophiles 1999; 3:163-72. [PMID: 10357003 DOI: 10.1007/s007920050112] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
In this study we propose revised structures for the two major compatible solutes of Rhodothermus marinus. We have also examined the accumulation of compatible solutes by the type strains of the slightly halophilic and thermophilic species Rhodothermus marinus and Rhodothermus obamensis at several growth temperatures and salinities. The major solutes of R. marinus were identified as alpha-mannosylglycerate (alpha-MG) and alpha-mannosylglyceramide (alpha-MGA), whereas R. obamensis accumulated only alpha-mannosylglycerate. The total osmolyte content was higher during the early exponential phase and decreased abruptly as growth continued into the stationary phase. At low growth temperatures. R. marinus responded to water stress by accumulation of alpha-mannosylglycerate and its amide, in addition to low levels of trehalose, glutamate, and glucose. At the highest growth temperature, alpha-mannosylglycerate was the major compatible solute and alpha-mannosylglyceramide was not detected. When both compounds were present, an increase in the salinity of the growth medium favored the accumulation of alpha-mannosylglyceramide over alpha-mannosylglycerate. The absence of alpha-mannosylglyceramide in R. obamensis at all growth temperatures and salinities constituted the most pronounced difference in the profiles of compatible solute accumulation by the two strains. Trehalose was also a prominent solute in this organism. Both organisms accumulated higher levels of alpha-mannosylglycerate as the temperature was raised. The importance of the two compounds in the mechanisms of thermoadaptation and osmoadaptation is discussed.
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Affiliation(s)
- Z Silva
- Departamento de Bioquímica, Universidade de Coimbra, Portugal
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Abstract
The accumulation of intracellular organic solutes was examined in six species of the order Thermotogales by nuclear magnetic resonance spectroscopy. The newly discovered compounds di-2-O-beta-mannosyl-di-myo-inositol-1,1'(3,3')-phosphate and di-myo-inositol-1,3'-phosphate were identified in Thermotoga maritima and Thermotoga neapolitana. In the latter species, at the optimum temperature and salinity the organic solute pool was composed of di-myo-inositol-1,1'(3,3')-phosphate, beta-glutamate, and alpha-glutamate in addition to di-myo-inositol-1,3'-phosphate and di-2-O-beta-mannosyl-di-myo-inositol-1,1'(3,3')-phosphate. The concentrations of the last two solutes increased dramatically at supraoptimal growth temperatures, whereas beta-glutamate increased mainly in response to a salinity stress. Nevertheless, di-myo-inositol-1,1'(3,3')-phosphate was the major compatible solute at salinities above the optimum for growth. The amino acids alpha-glutamate and proline were identified under optimum growth conditions in Thermosipho africanus, and beta-mannosylglycerate, trehalose, and glycine betaine were detected in Petrotoga miotherma. Organic solutes were not detected, under optimum growth conditions, in Thermotoga thermarum and Fervidobacterium islandicum, which have a low salt requirement or none.
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Affiliation(s)
- L O Martins
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Portugal
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Xavier KB, Martins LO, Peist R, Kossmann M, Boos W, Santos H. High-affinity maltose/trehalose transport system in the hyperthermophilic archaeon Thermococcus litoralis. J Bacteriol 1996; 178:4773-7. [PMID: 8759837 PMCID: PMC178256 DOI: 10.1128/jb.178.16.4773-4777.1996] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The hyperthermophilic marine archaeon Thermococcus litoralis exhibits high-affinity transport activity for maltose and trehalose at 85 degrees C. The K(m) for maltose transport was 22 nM, and that for trehalose was 17 nM. In cells that had been grown on peptone plus yeast extract, the Vmax for maltose uptake ranged from 3.2 to 7.5 nmol/min/mg of protein in different cell cultures. Cells grown in peptone without yeast extract did not show significant maltose or trehalose uptake. We found that the compound in yeast extract responsible for the induction of the maltose and trehalose transport system was trehalose. [14C]maltose uptake at 100 nM was not significantly inhibited by glucose, sucrose, or maltotriose at a 100 microM concentration but was completely inhibited by trehalose and maltose. The inhibitor constant, Ki, of trehalose for inhibiting maltose uptake was 21 nM. In contrast, the ability of maltose to inhibit the uptake of trehalose was not equally strong. With 20 nM [14C]trehalose as the substrate, a 10-fold excess of maltose was necessary to inhibit uptake to 50%. However, full inhibition was observed at 2 microM maltose. The detergent-solubilized membranes of trehalose-induced cells contained a high-affinity binding protein for maltose and trehalose, with an M(r) of 48,000, that exhibited the same substrate specificity as the transport system found in whole cells. We conclude that maltose and trehalose are transported by the same high-affinity membrane-associated system. This represents the first report on sugar transport in any hyperthermophilic archaeon.
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Affiliation(s)
- K B Xavier
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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Martins LO, Santos H. Accumulation of Mannosylglycerate and Di-myo-Inositol-Phosphate by Pyrococcus furiosus in Response to Salinity and Temperature. Appl Environ Microbiol 1995; 61:3299-303. [PMID: 16535119 PMCID: PMC1388573 DOI: 10.1128/aem.61.9.3299-3303.1995] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
(sup13)C and (sup1)H nuclear magnetic resonance spectroscopy was used to identify and quantify organic solutes accumulated by the hyperthermophilic archaeon Pyrococcus furiosus in response to temperature and salinity. Di-myo-inositol-phosphate and 2-O-(beta)-mannosylglycerate were the major organic solutes accumulated in these cells. The total intracellular organic solutes increased significantly in response either to an increase in temperature or to an increase in salinity, but (beta)-mannosylglycerate accumulated mainly at high salinities, whereas the concentration of di-myo-inositol-phosphate increased dramatically at supraoptimal growth temperatures. Glutamate was present at concentrations detectable by nuclear magnetic resonance only in cells grown in low-salinity media. The intracellular levels of K(sup+) are clearly dependent on the salinity of the medium, and the concentrations of this cation are high enough to counterbalance the negative charges of (beta)-mannosylglycerate and di-myo-inositol-phosphate in the cell. The results presented here together with those previously reported for Pyrococcus woesei (S. Scholz, J. Sonnenbichler, W. Schafer, and R. Hensel, FEBS Lett. 306:239-242, 1992) strongly support a role for di-myo-inositol-phosphate in thermoprotection.
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Martins LO, Sá-Correia I. Gellan gum biosynthetic enzymes in producing and nonproducing variants of Pseudomonas elodea. Biotechnol Appl Biochem 1991; 14:357-64. [PMID: 1777120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A pathway for the synthesis of the repeating tetrasaccharide units in gellan gum from Pseudomonas elodea is proposed. The enzymes presumed to be involved in the synthesis of the activated precursors UDP-glucose, TDP-rhamnose, and UDP-glucuronic acid were detected and assayed in crude cell extracts of the gellan-producing (Gel+) P. elodea ATCC 31461. The levels of UDP-glucose pyrophosphorylase and TDP-glucose pyrophosphorylase were higher in cells grown in media leading to higher gellan yields. Moreover, these enzymes exhibited lower values in cells of a Gel- variant, spontaneously obtained from the Gel+ wild type. The activation or repression of their synthesis is thought to be involved in the expression of the mucoid phenotype. Nevertheless, based on results here reported, the involvement of other enzymes, that catalyze steps downstream from the formation of the precursors cannot be excluded.
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Affiliation(s)
- L O Martins
- Lab. Engenharia Bioquímica, Instituto Superior Técnico, Lisboa Codex, Portugal
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Abstract
The Pseudomonas aeruginosa algD gene, encoding GDP-mannose dehydrogenase (GMD) and cloned at Chakrabarty's Laboratory in the expression vector pMMB24 (plasmid pVD211), was mobilized into P.aeruginosa strains 8821 and 8821M. Strain 8821M was a high-alginate-producing variant, spontaneously obtained from mucoid strain 8821, with derepressed levels of GMD, a key enzyme in the regulation of alginate biosynthesis, leading to the irreversible oxidation of GDP-mannose to GDP-mannuronic acid. A slight increase in the level of GMD, in both strains harboring the plasmid pVD211 and batch-grown at 37 degrees C without IPTG induction, led to the increase of production rate and the final concentration of alginate produced by control strains harboring the cloning vector. However, the viscosity of the aqueous solutions prepared with the alginate (3 g l-1) produced by mucoid strains harboring pVD211 was lower than those with the alginate produced by the controls (shear rates in the range 0.6-12 s-1). The specific activity of GMD assayed in crude extracts from cells harboring pVD211 and subjected to IPTG induction (0.5 and 3 mM) presented the highest values. However, either the rate of biosynthesis and final concentration of alginate or the viscosity of solutions prepared with the alginate produced by recombinants grown with IPTG were lower than that possible without overproduction. Therefore, the stimulation of the alginate pathway only by manipulating the rate of the step catalysed by GMD, although possible within certain levels, was at the expense of the final exopolysaccharide quality.
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Affiliation(s)
- L O Martins
- Laboratório de Engenharia Bioquímica, Instituto Superior Técnico, Lisboa, Portugal
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Martins LO, Jurado AS, Madeira VM. Composition of polar lipid acyl chains of Bacillus stearothermophilus as affected by temperature and calcium. Biochim Biophys Acta 1990; 1045:17-20. [PMID: 2369582 DOI: 10.1016/0005-2760(90)90198-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Bacillus stearothermophilus was grown within the temperature range of 48 to 68 degrees C in a complex medium and in the range of 45 to 72 degrees C in the presence of 2.5 mM Ca2+. The main fatty acids of lipid extracts contain 15 to 17 carbon atoms, mostly branched-chain species. The most prevalent saturated straight-chain fatty acid is n-C16. The total amount of branched-chain species decreases with increasing temperature of growth from 48 to 68 degrees C, whereas the straight-chain species increase. Thus, n-C16 almost doubles while i-C16, i-C17 and a-C17 decrease by 41.2, 28.9 and 41.9%, respectively. In the presence of Ca2+, the lipid metabolism favours the biosynthesis of straight-chain fatty acids with depression of branched-chain species, especially at lower temperatures. At high temperatures, Ca2+ has a less pronounced effect in the lipid biosynthesis. However, above 68 degrees C, a significant decrease is observed among the branched-chain fatty acids i-C15, i-C17 and a-C17 with a consequent increase in n-C16. Furthermore, a remarkable increase is observed in oleic acid (from 2.7% at 68 degrees C to 11.5% at the extreme 72 degrees C.
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Affiliation(s)
- L O Martins
- Centro de Biologia Celular, Universidade de Coimbra, Portugal
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da Rosa JC, Martins LO. [Retrosternal goiter. Data referring to 36 cases operated on the Hospital do Servidor Público Estadual Francisco Morato de Oliverira]. AMB Rev Assoc Med Bras 1972; 18:457-62. [PMID: 4539874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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