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1.
Int J Gynecol Cancer ; 32(1): 9-14, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34795019

RESUMO

During the COVID-19 pandemic, pressures on clinical services required adaptation to how care was prioritised and delivered for women with gynecological cancer. This document discusses potential 'salvage' measures when treatment has deviated from the usual standard of care. The British Gynaecological Cancer Society convened a multidisciplinary working group to develop recommendations for the onward management and follow-up of women with gynecological cancer who have been impacted by a change in treatment during the pandemic. These recommendations are presented for each tumor type and for healthcare systems, and the impact on gynecological services are discussed. It will be important that patient concerns about the impact of COVID-19 on their cancer pathway are acknowledged and addressed for their ongoing care.


Assuntos
COVID-19/epidemiologia , Neoplasias dos Genitais Femininos/epidemiologia , Neoplasias dos Genitais Femininos/terapia , Feminino , Ginecologia , Humanos , Pandemias , SARS-CoV-2/isolamento & purificação , Reino Unido/epidemiologia
2.
Int J Gynecol Cancer ; 31(2): 272-278, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33468564

RESUMO

The British Gynecological Cancer Society and the British Association of Gynecological Pathologists established a multidisciplinary consensus group comprising experts in surgical gynecological oncology, medical oncology, genetics, and laboratory science, and clinical nurse specialists to identify the optimal pathways to BRCA germline and tumor testing in patients with ovarian cancer in routine clinical practice. In particular, the group explored models of consent, quality standards identified at pathology laboratories, and experience and data from pioneering cancer centers. The group liaised with representatives from ovarian cancer charities to also identify patient perspectives that would be important to implementation. Recommendations from these consensus group deliberations are presented in this manuscript.


Assuntos
Proteína BRCA1 , Proteína BRCA2 , Carcinoma Epitelial do Ovário/genética , Neoplasias Ovarianas/genética , Consenso , Feminino , Predisposição Genética para Doença , Testes Genéticos/normas , Mutação em Linhagem Germinativa , Humanos , Reino Unido
3.
Biotechnol Bioeng ; 115(2): 390-400, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29030961

RESUMO

Methods of producing medium-chain-length poly-3-hydroxyalkanoate (mcl-PHA) with high content of the dominant subunit, 3-hydroxydecanoate (HD), were examined with an emphasis on a high yield of polymer from decanoic acid. High HD content was achieved by using a ß-oxidation knockout mutant of Pseudomonas putida KT2440 (designated as P. putida DBA-F1) or by inhibiting ß-oxidation with addition of acrylic acid (Aa) to wild type P. putida KT2440 in carbon-limited, fed-batch fermentations. At a substrate feed ratio of decanoic acid and acetic acid to glucose (DAA:G) of 6:4 g/g, P. putida DBA-F1 accumulated significantly higher HD (97 mol%), but much lower biomass (8.5 g/L) and PHA (42% of dry biomass) than the wild type. Both biomass and PHA concentrations were improved by decreasing the ratio of DAA:G to 4:6. Moreover, when the substrate feed ratio was further decreased to 2:8, 18 g/L biomass containing 59% mcl-PHA consisting of 100 mol% HD was achieved. The yield of PHA from decanoic acid was 1.24 (g/g) indicating that de novo synthesis had contributed to production. Yeast extract and tryptone (YET) addition allowed the mutant strain to accumulate 74% mcl-PHA by weight with 97 mol% HD at a production rate of 0.41 g/L/hr, at least twice that of published data for any ß-oxidation knock-out mutant. Higher biomass concentration was achieved with Aa inhibition of ß-oxidation in the wild type but the HD content (84 mol%) was less than that of the mutant. A carbon balance showed a marked increase in supernantant organic carbon for the mutant indicating overflow metabolism. Increasing the dominant monomer content (HD) greatly increased melting point, crystallinity, and rate of crystallization.


Assuntos
Ácidos Decanoicos/metabolismo , Poli-Hidroxialcanoatos/análise , Poli-Hidroxialcanoatos/metabolismo , Pseudomonas putida/metabolismo , Reatores Biológicos/microbiologia , Ácidos Decanoicos/química , Oxirredução , Poli-Hidroxialcanoatos/química , Pseudomonas putida/genética
4.
Can J Microbiol ; 64(1): 11-19, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29040817

RESUMO

Greater than 65% of canola and high-oleic soy oil fatty acids is oleic acid, which is readily converted to nonanoic (NA) and azelaic (AzA) acids by ozonolysis. NA is an excellent substrate for medium-chain-length polyhydroxyalkanoate (mcl-PHA) production but AzA has few uses. Pseudomonas citronellolis DSM 50332 and Pseudomonas fluorescens ATCC 17400, both able to produce mcl-PHA from fatty acids and to grow on AzA as the sole source of carbon and energy, were assessed for the accumulation of mcl-PHA from AzA and NA. In N-limited shake flasks using NA, P. citronellolis produced 32% of its dry biomass as mcl-PHA containing 78% 3-hydroxynonanoate with 22% 3-hydroxyheptanoate. Pseudomonas fluorescens produced only 2% PHA. N-limited P. citronellolis on AzA produced 20% dry weight PHA containing 75% 3-hydroxydecanoate and 25% 3-hydroxyoctanoate, indicative of de novo synthesis. Although selective pressure, including ß-oxidation inhibition, under well-controlled (chemostat) conditions was applied to P. citronellolis, no side-chain carboxyl groups were detected. It was concluded that one or more of FabG and PhaJ or the PHA synthase cannot catalyze reactions involving ω-carboxy substrates. However, a process based on oleic acid could be established if Pseudomonas putida was engineered to grow on AzA.


Assuntos
Caprilatos/metabolismo , Ácidos Dicarboxílicos/metabolismo , Ácidos Graxos/metabolismo , Poli-Hidroxialcanoatos/biossíntese , Pseudomonas/metabolismo , Aciltransferases/metabolismo , Biomassa , Carbono/metabolismo , Pseudomonas/crescimento & desenvolvimento
5.
Environ Sci Technol ; 49(1): 570-7, 2015 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-25521156

RESUMO

Using effect directed analysis, the presence of estrogenic components in untreated and biologically treated oil sands process water (OSPW) was detected with the yeast estrogenic screening assay after fractionation with solid phase extraction followed by reversed phase high performance liquid chromatography. Comparison of the composition, as determined by electrospray ionization combined with high-resolution linear trap quadropole (LTQ)-Orbitrap Velos Pro hybrid mass spectrometry (negative ion) of selected estrogenic and nonestrogenic fractions identified compounds that were uniquely present in the estrogenic samples, biologically treated and untreated. Of the 30 most abundant compounds, there were 14 possible nonaromatic structures and 16 possible aromatic structures. Based on the published literature, the latter are the most likely to cause estrogenicity and were O2, O3 and O4 C17 to C20 compounds with double bond equivalents between 6 and 10 and chemical formulas similar to estrone- and estradiol-like compounds. This study shows exact formulas and masses of possible estrogenic compounds in OSPW. These findings will help to focus study on the most environmentally significant components in OSPW.


Assuntos
Monitoramento Ambiental/métodos , Estrogênios/química , Campos de Petróleo e Gás , Solo/química , Águas Residuárias/química , Poluição da Água/análise , Ácidos Carboxílicos/análise , Fracionamento Químico , Cromatografia de Fase Reversa , Peso Molecular , Análise de Componente Principal , Extração em Fase Sólida , Espectrometria de Massas por Ionização por Electrospray , Poluentes Químicos da Água/análise
6.
J Ind Microbiol Biotechnol ; 42(4): 637-46, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25563970

RESUMO

A medium-chain-length poly-3-hydroxyalkanote (MCL-PHA) depolymerase knockout mutant of Pseudomonas putida KT2440 was produced by double homologous recombination. A carbon-limited shake-flask study confirmed that depolymerase activity was eliminated. Lysis of both mutant and wild-type strains occurred under these conditions. In carbon-limited, fed-batch culture, the yield of unsaturated monomers from unsaturated substrate averaged only 0.62 mol mol(-1) for the phaZ minus strain compared to 0.72 mol mol(-1) for the wild type. The mutant strain also produced more CO2 and less residual biomass from the same amount of carbon substrate. However, most results indicated that elimination of PHA depolymerase activity had little impact on the overall yield of biomass and PHA.


Assuntos
Técnicas de Cultura Celular por Lotes , Carbono/metabolismo , Deleção de Genes , Poli-Hidroxialcanoatos/biossíntese , Poli-Hidroxialcanoatos/química , Pseudomonas putida/genética , Pseudomonas putida/metabolismo , Biomassa , Dióxido de Carbono/metabolismo , Técnicas de Inativação de Genes
7.
Biodegradation ; 26(4): 313-25, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26077118

RESUMO

This is the first study to report that bacteria from the genera Ochrobactrum, Brevundimonas and Bacillus can be isolated by growth on naphthenic acids (NAs) extracted from oil sands process water (OSPW). These pure cultures were screened for their ability to use a range of aliphatic, cyclic and aromatic NA surrogates in 96-well microtiter plates using water-soluble tetrazolium redox dyes (Biolog Redox Dye H) as the indicator of metabolic activity. Of the three cultures, Ochrobactrum showed most metabolic activity on the widest range of NA surrogates. Brevundomonas and especially Ochrobactrum had higher metabolic activity on polycyclic aromatic compounds than other classes of NA surrogates. Bacillus also oxidized a wide range of NA surrogates but not as well as Ochrobactrum. Using this method to characterize NA utilisation, one can identify which NAs or NA classes in OSPW are more readily degraded. Since aromatic NAs have been shown to have an estrogenic effect and polycyclic monoaromatic compounds have been suggested to pose the greatest environmental threat among the NAs, these bacterial genera may play an important role in detoxification of OSPW. Furthermore, this study demonstrates that bacteria belonging to the genera Ochrobactrum and Bacillus can also degrade surrogates of tricyclic NAs.


Assuntos
Cultura Axênica , Bactérias/metabolismo , Ácidos Carboxílicos/química , Estradiol/química , Bacillus/metabolismo , Bactérias/classificação , Bactérias/isolamento & purificação , Biodegradação Ambiental , Reatores Biológicos/microbiologia , Células Imobilizadas , Corantes/química , Ochrobactrum/metabolismo , Campos de Petróleo e Gás , Oxirredução , Hidrocarbonetos Policíclicos Aromáticos/química , RNA Ribossômico 16S/genética , Microbiologia do Solo , Testes de Toxicidade Aguda
8.
World J Microbiol Biotechnol ; 30(4): 1409-16, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24287944

RESUMO

The aim of this study was to increase the density of wild type Cupriavidus necator H16 biomass grown on fructose in order to produce sufficient copolymer of short-chain-length (scl) and medium-chain-length (mcl) polyhydroxyalkanoate (PHA) from canola oil for mechanical testing of the PHA. Initial batch cultivation on fructose was followed by exponential feeding of fructose at a predetermined µ to achieve 44.4 g biomass/l containing only 20 % w/w of polyhydroxybutyrate (PHB) with a Y(x/fructose) of 0.44 g/g. In a third stage, canola oil was added under N-limited conditions to produce 92 g/l of biomass with 48 % w/w scl-mcl PHA. Using known standards, the PHA composition was confirmed by GC-MS analysis as 99.81 % 3-hydroxybutyrate, 0.06 % 3-hydroxyvalerate, 0.09 % 3-hydroxyhexanoate and 0.04 % 3-hydroxyoctanoate. The melting temperature (179 °C), crystallinity (54 %), tensile stress (25.1 Mpa) and Young's modulus (698 Mpa) for a PHB standard decreased to 176 °C, 52 %, 19.1 and 443 Mpa respectively for C. necator PHA produced in the 3-stage process.


Assuntos
Cupriavidus necator/crescimento & desenvolvimento , Cupriavidus necator/metabolismo , Ácidos Graxos Monoinsaturados/metabolismo , Frutose/metabolismo , Poli-Hidroxialcanoatos/metabolismo , Biomassa , Cromatografia Gasosa , Meios de Cultura/química , Espectrometria de Massas , Poli-Hidroxialcanoatos/química , Óleo de Brassica napus , Temperatura de Transição
9.
Chemosphere ; 362: 142540, 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38851514

RESUMO

The rate of mass transfer of lower molecular weight hydrocarbons (naphtha) from bitumen drops in mature fine tailings of oil sand tailings ponds (OSTPs) may control their bioavailability and the associated rate of GHG production. Experiments were conducted using bitumen drops spiked with o-xylene and 1-methylnaphthalene to determine the mass transfer rate of these naphtha components from bitumen drops. The results were compared to simulations using a multi-component numerical model that accounted for transport in the drop and across the oil-water interface. The results demonstrate rate-limited mass transfer, with aqueous concentrations after 60 days of dissolution that were different than those in equilibrium with the initial drop composition (less for o-xylene and greater for 1-methylnaphthalene). The simulations suggest that mole fractions were unchanged at the center of the drop, resulting in concentration gradients out to the oil-water interface. Numerical simulations conducted using different drop sizes and bitumen viscosities also suggest the potential for persistent naphtha dissolution, where the time required to deplete 80% of the o-xylene and 1-methylnaphthalene mass from an oil drop was estimated to be on the order of months to years for mm-sized drops, and years to decades for cm-sized drops assuming instantaneous biodegradation in the aqueous phase surrounding the bitumen.

10.
Biomacromolecules ; 13(9): 2926-32, 2012 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-22871146

RESUMO

When grown in a nonanoic acid-limited chemostat at a dilution rate of 0.25 h(-1), Pseudomonas putida KT2440 produced poly(3-hydroxynonanoate-co-3-hydroxyheptanoate) containing 68 mol % 3-hydroxynonanoate (C9) and 32 mol % 3-hydroxyheptanoate (C7). Under the same conditions, but in the presence of acrylic acid, a fatty acid ß-oxidation inhibitor, the C9 monomer content increased to 88 mol %. Cofeeding glucose (3.9 g L(-1)) and nonanoic acid (2.9 ± 0.1 g L(-1)) in continuous culture with 0.2 g L(-1) of acrylic acid in the feed, further increased the C9 content to 95 mol %. A yield of PHA from nonanoic acid of 0.93 mol mol(-1) was attained. PHA with a 3-hydroxyoctanoate (C8) content of 98 mol % was produced with the same cofeeding methodology from octanoic acid. As the dominant monomer content increased, the melting point of the poly(3-hydroxynonanoate) copolymers increased from 46 to 63 °C and that of the poly(3-hydroxyoctanoate) copolymers from 54 to 62 °C. All copolymer compositions resulted in elongation to break values of about 1300%, but tensile strength at break and Young's modulus both increased with increasing amounts of the dominant monomer.


Assuntos
Materiais Biocompatíveis/química , Caprilatos/metabolismo , Ácidos Graxos/metabolismo , Poli-Hidroxialcanoatos/química , Pseudomonas putida/metabolismo , Acrilatos/farmacologia , Biocatálise , Materiais Biocompatíveis/metabolismo , Reatores Biológicos , Meios de Cultura/química , Módulo de Elasticidade , Fermentação/efeitos dos fármacos , Glucose/metabolismo , Teste de Materiais , Poli-Hidroxialcanoatos/agonistas , Poli-Hidroxialcanoatos/biossíntese , Pseudomonas putida/efeitos dos fármacos , Resistência à Tração
11.
Microorganisms ; 9(11)2021 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-34835351

RESUMO

We examined greenhouse gas (GHG) production upon the addition of ammonium and phosphate to mature fine tailing (MFT) samples from Alberta's Pond 2/3 (at 5 and 15 m) and Pond 7 (12.5 m) in microcosm studies. The methane production rate in unamended Pond 2/3 MFT correlated with sample age; the production rate was higher in the less dense, more recently discharged MFT samples and lower in the denser, deeper sample. Adding small amounts of naphtha increased methane production, but there was no correlation with increasing naphtha, indicating that naphtha may partition into bitumen, reducing its bioavailability. Although non-detectable phosphate and low ammonium in the pore water indicate that these nutrients were potentially limiting microbial activity, their addition did not significantly affect methanogenesis but somewhat enhanced sulphate and nitrate reduction. Neither ammonium nor phosphate were detected in the pore water when added at low concentrations, but when added at high concentrations, 25-35% phosphate and 30-45% ammonium were lost. These ions likely sorbed to MFT minerals such as kaolinite, which have microbial activity governed by phosphate/ammonium desorption. Hence, multiple limitations affected microbial activity. Sulphate was less effective than nitrate was in inhibiting methanogenesis because H2S may be a less effective inhibitor than NOx- intermediates are, and/or H2S may be more easily abiotically removed. With nitrate reduction, N2O, a potent GHG was produced but eventually metabolized.

12.
JRSM Open ; 11(6): 2054270417744502, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32551131

RESUMO

Computed tomography scanning could be safely used in later pregnancy to aid diagnosis and target management of the acute abdomen.

13.
J Biotechnol ; 139(1): 78-83, 2009 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-18955091

RESUMO

Soluble methane monooxygenase (sMMO) can degrade many chlorinated and aromatic pollutants. It is produced by certain methanotrophs such as Methylosinus trichosporium when grown on methane under copper limitation but, due to its low aqueous solubility, methane cannot support dense biomass growth. Since it is water soluble, methanol may be a more attractive growth substrate, but it is widely believed that sMMO is not produced on methanol. In this study, when the growth-limiting substrate was switched from methane to methanol, in the presence of the particulate MMO inhibitor, allylthiourea, growth of M. trichosporium OB3b continued unabated and sMMO activity was completely retained. When allylthiourea was then removed, sMMO activity was maintained for an additional 24 generations, albeit at a slightly lower level due to the presence of 0.70 microM of Cu(2+) in the feed medium. While a biomass density of only 2 g l(-1) could be obtained on methane, 7.4 g l(-1) was achieved by feeding methanol exponentially, and 29 g l(-1) was obtained using a modified feeding strategy employing on-line carbon dioxide production measurement. It was concluded that methanol can be employed to produce large amounts of M. trichosporium biomass containing sMMO.


Assuntos
Metanol/metabolismo , Methylosinus trichosporium/metabolismo , Oxigenases/metabolismo , Algoritmos , Biomassa , Dióxido de Carbono/metabolismo , Cobre/metabolismo , Formaldeído/metabolismo , Metano/metabolismo , Methylosinus trichosporium/enzimologia , Methylosinus trichosporium/crescimento & desenvolvimento , Solubilidade , Tioureia/análogos & derivados , Tioureia/metabolismo
14.
Appl Microbiol Biotechnol ; 82(2): 333-9, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19107472

RESUMO

Methanotrophs expressing soluble methane monooxygenase (sMMO) may find use in a variety of industrial applications. However, sMMO expression is strongly inhibited by copper, and the growth rate may be limited by the aqueous solubility of methane. In this study, addition of allylthiourea decreased intracellular copper in Methylosinus trichosporium OB3b, allowing sMMO production at Cu/biomass ratios normally not permitting sMMO synthesis. The presence of about 1.5 micromoles intracellular Cu g(-1) dry biomass resulted in sMMO activity of about 250 micromoles 1-napthol formed per hour gram dry biomass whether this intracellular Cu concentration was achieved by Cu limitation or by allylthiourea addition. No loss of sMMO activity occurred when the growth substrate was switched from methane to methanol when allylthiourea had been added to growth medium containing copper. Addition of copper to medium that was almost copper-free increased the yield of dry biomass from methanol from 0.20 to 0.36 g g(-1), demonstrating that some copper was necessary for good growth. This study demonstrated a method by which sMMO can be produced by M. trichosporium OB3b while growing on methanol in copper-containing medium.


Assuntos
Proteínas de Bactérias/metabolismo , Cobre/metabolismo , Methylosinus trichosporium/enzimologia , Oxigenases/metabolismo , Tioureia/análogos & derivados , Proteínas de Bactérias/genética , Biomassa , Metano/metabolismo , Metanol/metabolismo , Methylosinus trichosporium/genética , Methylosinus trichosporium/crescimento & desenvolvimento , Methylosinus trichosporium/metabolismo , Oxigenases/genética , Solubilidade , Tioureia/metabolismo
15.
Appl Microbiol Biotechnol ; 82(4): 657-62, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19050862

RESUMO

Unsaturated medium-chain-length polyhydroxyalkanoates (MCL-PHA) were produced at a productivity of 0.63-1.09 g PHA l(-1) h(-1) with final PHA content ranging from 42.6 to 55.8% in single-stage, carbon-limited, fed-batch fermentations of Pseudomonas putida KT2440. A mixture of nonanoic acid (NA) and 10-undecenoic acid (UDA=) was fed exponentially to control growth rate. Varying the specific growth rate (0.14 h(-1) vs. 0.23 h(-1)) at similar substrate feed ratios (NA:UDA= = 5:1) had little effect on the final PHA content and relative composition. However, decreasing the NA:UDA= ratio decreased the final amount of PHA produced from 56% with NA:UDA= = 5.07:1 to only 42% at NA:UDA= = 2.47:1. The molar fraction of all 3-hydroxyalkanoate monomers in the PHA product was relatively constant throughout each fermentation, indicating that the final product was homogeneous rather than a mixture of different copolymers. A linear relationship between unsaturation of the PHA produced and unsaturation of the carbon feed was found, which demonstrates the feasibility of producing unsaturated MCL-PHAs with controlled polymeric composition in a fed-batch process.


Assuntos
Reatores Biológicos/microbiologia , Meios de Cultura/química , Poli-Hidroxialcanoatos/metabolismo , Pseudomonas putida/metabolismo , Meios de Cultura/metabolismo , Fermentação , Cinética , Poli-Hidroxialcanoatos/química , Pseudomonas putida/química , Pseudomonas putida/crescimento & desenvolvimento
16.
Int J Biol Macromol ; 108: 902-908, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29102788

RESUMO

The effects of carboxylation (via mercaptoundecanoic acid) on colloidal properties of medium-chain-length poly(3-hydroxyalkanoate) (mcl-PHA) latexes were studied. Non-ionic surfactants tested at 0.4% solids of 11 mol% carboxylated mcl-PHA produced similar particle sizes and particle size distribution (PdI) with Triton X-100 giving the smallest size. When Triton X-100 was combined with an ionic surfactant, smaller nanoparticles (97.1±1.1 to 121.7±5.7nm) with narrower PdIs (0.21±0.001 to 0.25±0.003) were obtained. The combination of SDS and Triton X-100 gave the smallest particle size (97.1±1.1nm) and narrowest PdI (0.21±0.001). At higher solids content (10%), a mixture of 5mM SDS and 20mM Triton X-100 produced stable (zeta potential=-39.6± 0.9) 170.3±4.6nm nanoparticles. As carboxylation increased, particle size and hydrophobicity decreased while stability increased. When comparing nanoparticles of similar size and stability, carboxylated mcl-PHA needed ∼50% less surfactant to make stable nanoparticles compared to aliphatic mcl-PHAs, with the amount of surfactant required decreasing as carboxylation increased. This is the first study to show that stable nanoparticle suspensions of a range of carboxylated mcl-PHAs above 0.4% solids can be made using a mixture of ionic and nonionic surfactants.


Assuntos
Nanopartículas/química , Poli-Hidroxialcanoatos/química , Fermentação , Espectroscopia de Ressonância Magnética , Peso Molecular , Tamanho da Partícula , Poli-Hidroxialcanoatos/biossíntese , Tensoativos/química
17.
Int J Biol Macromol ; 119: 1248-1255, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30092307

RESUMO

We investigated the effects of the structure of medium-chain-length polyhydroxyalkanoates (MCL-PHAs) on their thermal properties and crystallization kinetics. The predominantly homopolymeric poly(3-hydroxydecanoate), P(3HD)-98, and the poly(3-hydroxydodecanoate), P(3HDD), exhibited sharp crystallization peaks upon cooling, with the latter exhibiting faster crystallization rates. A chemical modification strategy involving reaction with dicumyl peroxide and triallyl trimesate coagent was implemented to introduce branching and enhance the crystallization kinetics of P(3HD-98). Increases in the exothermic crystallization temperature by 8 °C and in the overall crystallinity of the P(3HD)-98 were observed upon chemical modification. The Avrami crystallization kinetic parameters obtained by fitting the isothermal crystallization data revealed a significant increase in the crystallization rate of the modified P(3HD)-98.


Assuntos
Poli-Hidroxialcanoatos/química , Temperatura , Cristalização , Cinética , Transição de Fase
18.
J Biotechnol ; 132(3): 280-2, 2007 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-17442441

RESUMO

A method was developed to increase the yield of MCL-PHA from nonanoic acid in the PHA accumulation phase. Pseudomonas putida KT2440 was grown on glucose until ammonium-limitation was imposed. In the second (accumulation) stage, either glucose, nonanoic acid, or a mixture of these carbon and energy sources was supplied. Since the medium-chain-length poly-3-hydroxyalkanoate (MCL-PHA) subunits produced are unique for each carbon source, their relative contribution to PHA yield could be calculated. Y(C7+C9)/NA was 0.254 mol mol(-1) during PHA synthesis from nonanoic acid. Y(C8+C10)/G was only 0.057 mol mol(-1) during PHA synthesis from glucose. When nonanoic acid and glucose were fed together, Y(C7+C8)/NA almost doubled to 0.450 mol mol(-1) while Y(C8+C10)/G decreased to 0.011 mol mol(-1). These results demonstrate that substantial savings can be obtained by feeding glucose with substrates that are good for PHA production but much more expensive than glucose.


Assuntos
Biotecnologia/métodos , Ácidos Graxos/metabolismo , Fermentação , Glucose/metabolismo , Poli-Hidroxialcanoatos/biossíntese , Pseudomonas putida/metabolismo , Carbono
19.
J Microbiol Methods ; 67(2): 212-9, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16753235

RESUMO

A methodology was developed for the extraction of medium-chain-length poly-3-hydroxyalkanoates (mcl-PHA) from Pseudomonas putida. It was determined that if dry P. putida biomass containing mcl-PHA was washed in 20 volumes of methanol for 5 min followed by Soxhlet extraction in 10 volumes of acetone for 5 h, almost all of the PHA could be recovered with no detectable loss of molecular weight. Biomass containing higher amounts of PHA required less methanol during the pretreatment step but more acetone in the solvent extraction step than biomass containing less PHA. Further purification could be achieved by redissolving the PHA in acetone and reprecipitating in cold methanol. UV spectroscopy at 241 and 275 nm could be used as an indication of product purity.


Assuntos
Acetona/química , Microbiologia Industrial/métodos , Poliésteres/isolamento & purificação , Pseudomonas putida/química , Biomassa , Solventes/química , Espectrofotometria Ultravioleta
20.
J Biotechnol ; 218: 102-7, 2016 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-26689481

RESUMO

Decanoic acid is an ideal substrate for the synthesis of medium-chain-length poly-3-hydroxyalkanoate (MCL-PHA), but its use for this purpose has only previously been studied in shake-flasks likely due to its surfactant properties, low aqueous solubility and high melting temperature. A fed-batch fermentation process was developed for the production of MCL-PHA from decanoic acid using Pseudomonas putida KT2440. Decanoic acid was kept in liquid form by heating or by mixing with acetic acid to prevent crystallization. Different ratios of decanoic acid:acetic acid:glucose (DA:AA:G) were fed to produce a specific growth rate of 0.15 h(-1). This method produced a maximum of 39 g L(-1) dry biomass containing 67% MCL-PHA when the DA:AA:G ratio was 5:1:4. However, a declining growth rate occurred in the late stage of fermentation, resulting in decanoic acid accumulation in the bioreactor leading to foaming. The duration of MCL-PHA production was extended by shifting from exponential to linear feeding before accumulation of decanoic acid. This resulted in 75 g L(-1) biomass containing 74% PHA and an overall PHA productivity of 1.16 g L(-1)h(-1) with the production of each gram of PHA requiring only 1.16 g of decanoic acid. The final PHA composition (on a molar basis) was 78% 3-hydroxydecanoate, 11% 3-hydroxyoctanoate and 11% 3-hydroxyhexanoate.


Assuntos
Técnicas de Cultura Celular por Lotes/métodos , Ácidos Decanoicos/metabolismo , Poliésteres/metabolismo , Ácido Acético/metabolismo , Biomassa , Reatores Biológicos , Caproatos/metabolismo , Caprilatos/metabolismo , Fermentação , Glucose/metabolismo , Pseudomonas putida/metabolismo
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