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1.
Int J Syst Evol Microbiol ; 70(5): 3497-3503, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32379018

RESUMO

A novel rod-shaped and Gram-stain-negative bacterium, designated strain RZ05T, was isolated from a sand sample collected from the intertidal zone of the Yellow Sea, PR China. Results of phylogenetic analysis based on 16S rRNA gene sequences revealed that strain RZ05T clusters within the genus Maribacter, a member of the family Flavobacteriaceae, and has the highest sequence similarity to Maribacter polysiphoniae KCTC 22021T (97.8 %), followed by Maribacter arenosus KCTC 52191T (97.2 %). Cells of this strain were observed to be aerobic, oxidase- and catalase-positive, motile by gliding and formed yellow colonies. Growth occurred at 7-40 °C (optimum, 30 °C), at pH 6.5-9.5 (optimum, pH 7.0) and with 0.5-6 % (optimum, 2 %) NaCl. Its polar lipid profile included phosphatidylethanolamine, two unidentified glycolipids, one unidentified aminolipid and four unidentified lipids. The major cellular fatty acids were iso-C15 : 0, iso-C15 : 1 G, iso-C17 : 0 3-OH, iso-C16 : 0 3-OH, iso-C15 : 0 3-OH, summed feature 9 (10-methyl C16 : 0/iso-C17 : 1 ω9c) and summed feature 3 (iso-C15 : 0 2-OH/C16 : 1 ω7c/C16 : 1 ω6c). The only respiratory quinone was menaquinone 6 (MK-6). The genome of strain RZ05T was 4.65 Mbp with a G+C content of 38.9 mol%. The average nucleotide identity and in silico DNA-DNA hybridization values between strain RZ05T and its most closely related type strain M. polysiphoniae KCTC 22021T were 80.3 and 26.3  %, respectively. The results of phylogenetic, phenotypic and chemotaxonomic analyses indicated that strain RZ05T represents a novel species of the genus Maribacter, for which the name Maribacter luteus sp. nov. is proposed. The type strain is RZ05T (=KCTC 62834T=MCCC 1K03617T).


Assuntos
Filogenia , Areia/microbiologia , Água do Mar/microbiologia , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Bacteriano/genética , Ácidos Graxos/química , Flavobacteriaceae/classificação , Hibridização de Ácido Nucleico , Fosfatidiletanolaminas/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/química
2.
Molecules ; 24(23)2019 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-31779169

RESUMO

The solid dispersion technique, which is widely used in the medical field, was applied to prepare a pesticide dosage form of emamectin benzoate (EM). The preparation, physicochemical characterization, aqueous solubility, release dynamics, photolytic degradation, bioactivity, and sustained-release effects of the prepared EM solid dispersions were studied by a solvent method, using polymer materials as the carriers. Water-soluble polyvinyl pyrrolidone (PVP) K30 and water-insoluble polyacrylic resin (PR)III were used as the carriers. The influence of various parameters, such as different EM:PVP-K30 and EM:PRIII feed ratios, solvent and container choices, rotational speed and mixing time effects on pesticide loading, and the entrapment rate of the solid dispersions were investigated. The optimal conditions for the preparation of EM-PVP-K30 solid dispersions required the use of methanol and a feed ratio between 1:1 and 1:50, along with a rotational speed and mixing time of 600 rpm and 60 min, respectively. For the preparation of EM-PRIII solid dispersions, the use of methanol and a feed ratio between 1:4 and 1:50 were required, in addition to the use of a porcelain mortar for carrying out the process. Under optimized conditions, the prepared EM-PVP-K30 solid dispersions resembled potato-like, round, and irregular structures with a jagged surface. In contrast, the EM-PRIII solid dispersions were irregular solids with a microporous surface structure. The results of X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), ultraviolet (UV) spectrometry, and infrared (IR) spectrometry showed that the solid dispersions were formed by intermolecular hydrogen bonding. The solid dispersion preparation in PVP-K30 significantly improved the solubility and dissolution rate of EM, particularly the aqueous solubility, which reached a maximum of 37.5-times the EM technical solubility, when the feed ratio of 1:10 was employed to prepare the dispersion. Importantly, the wettable powder of EM-PVP-K30 solid dispersion enhanced the insecticidal activity of EM against the Plutella xylostella larvae. Furthermore, the solid dispersion preparation in PRIII afforded a significant advantage by prolonging the EM technical release in water at a pH below 7.0, especially when the PRIII content in solid dispersions was high. While the amplified toxicity of the wettable powder of EM-PRIII solid dispersions against the P. xylostella larvae showed no significant differences from that of the EM technical, the long-term toxicity under the field condition was much better than that of the commercially available EM 1.5% emulsifiable concentrate. Notably, solid dispersions with both the PVP-K30 and PRIII carriers reduced the effect of UV photolysis.


Assuntos
Preparações de Ação Retardada/química , Ivermectina/análogos & derivados , Tecnologia Farmacêutica/métodos , Varredura Diferencial de Calorimetria/métodos , Química Farmacêutica/métodos , Interações Hidrofóbicas e Hidrofílicas , Ivermectina/química , Polímeros/química , Polivinil/química , Pós/química , Pirrolidinas/química , Solubilidade , Solventes/química , Espectrofotometria Infravermelho/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Raios Ultravioleta , Difração de Raios X/métodos
3.
J Agric Food Chem ; 61(50): 12219-25, 2013 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-24283703

RESUMO

Emamectin benzoate is highly effective against insect pests and widely used in the world. However, its biological activity is limited because of high resistance of target insects and rapid degradation speed in fields. Preparation and physicochemical characterization of degradable microcapsules of emamectin benzoate were studied by modified solvent evaporation/extraction method using polylactide (PLA) as wall material. The influence of different compositions of the solvent in internal organic phase and external aqueous phase on diameter, span, pesticide loading, and entrapment rate of the microspheres was investigated. The results indicated that the process of solvent extraction and the formation of the microcapsules would be accelerated by adding water-miscible organic solvents such as ethyl ether, acetone, ethyl acetate, or n-butanol into internal organic phase and external aqueous phase. Accelerated formation of the microcapsules would result in entrapment rates of emamectin benzoate increased to as high as 97%. In addition, by adding ethanol into the external aqueous phase, diameters would reduce to 6.28 µm, whereas the loading efficiency of emamectin benzoate did not increase. The PLA microspheres prepared under optimum conditions were smoother and more spherical. The degradation rate in PLA microspheres of emamectin benzoate on the 10th day was 4.29 ± 0.74%, whereas the degradation rates of emamectin benzoate in methanol solution and solid technical material were 46.3 ± 2.11 and 22.7 ± 1.51%, respectively. The PLA skeleton had combined with emamectin benzoate in an amorphous or molecular state by using differential scanning calorimetry (DSC) determination. The results indicated that PLA microspheres of emamectin benzoate with high entrapment rate, loading efficiency, and physicochemical characteristics could be obtained by adding water-miscible organic solvents into the internal organic phase and external aqueous phase.


Assuntos
Química Farmacêutica/métodos , Inseticidas/química , Ivermectina/análogos & derivados , Poliésteres/química , Ivermectina/química , Microesferas , Tamanho da Partícula
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