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1.
Huan Jing Ke Xue ; 40(10): 4685-4690, 2019 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854839

RESUMO

Antibiotic resistance genes (ARGs) are considered to be emerging environmental contaminants. ARGs are frequently detected in municipal solid waste landfill and its leachate. In this study, high-throughput quantitative PCR techniques were used to investigate the dynamics of ARGs during the treatment process of landfill leachate. The results showed that ARGs in leachate were diverse and abundant, and leachate treatment could effectively reduce their abundance; the absolute abundance of ARGs was reduced to 9.2×1010 copies·L-1, which was five orders of magnitude less than the abundance of the influent. However, the range and abundance of antibiotic resistance genes in the leachate effluents were still high compared to the natural environment. Therefore, the secondary contamination of ARGs might be caused by leachate being directly discharged into municipal sewage system. In this regard, ecological and environmental risk is an inconvenient truth. Furthermore, strong correlations indicate that heavy metals and mobile genetic elements (MGEs) in landfill leachate might influence the transfer of ARGs.


Assuntos
Antibacterianos , Resistência Microbiana a Medicamentos , Resíduos Sólidos , Poluentes Químicos da Água , Bactérias/genética , Resistência Microbiana a Medicamentos/genética , Genes Bacterianos , Instalações de Eliminação de Resíduos
2.
Nat Prod Bioprospect ; 7(4): 329-334, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28634711

RESUMO

Tamoxifen resistance (TamR) is the underlying cause of treatment failure in many breast cancer patients receiving tamoxifen. In order to look for noncytotoxic natural products with the ability to reverse TamR, an extract from strain Streptomyces sp. KIB-H0495 was detected to be active. Subsequent large scale fermentation and isolation led to the isolation of four α-pyrone derivatives including two new compounds, violapyrones J (2) and K (3), and two known analogues, violapyrones B (1) and I (4). Further bioactivity assays indicated that only 1 and 3 exerted potent resensitization effects on MCF-7/TamR cells at a concentration of 1 µM. Owing to the simple structures of 1 and 3, these two compounds might have potential for further investigation as novel tamoxifen resensitization agent in breast cancer chemotherapy.

3.
Microb Cell Fact ; 14: 152, 2015 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-26400541

RESUMO

BACKGROUND: Avermectin and milbemycin are important 16-membered macrolides that have been widely used as pesticides in agriculture. However, the wide use of these pesticides inevitably causes serious drug resistance, it is therefore imperative to develop new avermectin and milbemycin analogs. The biosynthetic gene clusters of avermectin and milbemycin have been identified and the biosynthetic pathways have been elucidated. Combinatorial biosynthesis by domain swap provides an efficient strategy to generate chemical diversity according to the module polyketide synthase (PKS) assembly line. RESULTS: The substitution of aveDH2-KR2 located in avermectin biosynthetic gene cluster in the industrial avermectin-producing strain Streptomyces avermitilis NA-108 with the DNA regions milDH2-ER2-KR2 located in milbemycin biosynthetic gene cluster in Streptomyces bingchenggensis led to S. avermitilis AVE-T27, which produced ivermectin B1a with high yield of 3450 ± 65 µg/ml. The subsequent replacement of aveLAT-ACP encoding the loading module of avermectin PKS with milLAT-ACP encoding the loading module of milbemycin PKS led to strain S. avermitilis AVE-H39, which produced two new avermectin derivatives 25-ethyl and 25-methyl ivermectin (1 and 2) with yields of 951 ± 46 and 2093 ± 61 µg/ml, respectively. Compared to commercial insecticide ivermectin, the mixture of 25-methyl and 25-ethyl ivermectin (2:1 = 3:7) exhibited 4.6-fold increase in insecticidal activity against Caenorhabditis elegans. Moreover, the insecticidal activity of the mixture of 25-methyl and 25-ethyl ivermectin was 2.5-fold and 5.7-fold higher than that of milbemycin A3/A4 against C. elegans and the second-instar larva of Mythimna separate, respectively. CONCLUSIONS: Two new avermectin derivatives 25-methyl and 25-ethyl ivermectin were generated by the domain swap of avermectin PKS. The enhanced insecticidal activity of 25-methyl and 25-ethyl ivermectin implied the potential use as insecticide in agriculture. Furthermore, the high yield and genetic stability of the engineered strains S. avermitilis AVE-T27 and AVE-H39 suggested the enormous potential in industrial production of the commercial insecticide ivermectin and 25-methyl/25-ethyl ivermectins, respectively.


Assuntos
Regulação Bacteriana da Expressão Gênica/genética , Ivermectina/análogos & derivados , Ivermectina/síntese química , Policetídeo Sintases/metabolismo , Animais , Inseticidas/metabolismo , Ivermectina/metabolismo , Modelos Moleculares
4.
Genome ; 56(11): 677-89, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24299107

RESUMO

Streptomyces bingchenggensis is a soil bacterium that produces milbemycins, a family of macrolide antibiotics that are commercially important in crop protection and veterinary medicine. In addition, S. bingchenggensis produces many other natural products including the polyether nanchangmycin and novel cyclic pentapeptides. To identify the gene clusters involved in the biosynthesis of these compounds, and better clarify the biochemical pathways of these gene clusters, the whole genome of S. bingchenggensis was sequenced, and the transcriptome profile was subsequently investigated by microarray. In comparison with other sequenced genomes in Streptomyces, S. bingchenggensis has the largest linear chromosome consisting of 11 936 683 base pairs (bp), with an average GC content of 70.8%. The 10 023 predicted protein-coding sequences include at least 47 gene clusters correlated with the biosynthesis of known or predicted secondary metabolites. Transcriptional analysis demonstrated an extremely high expression level of the milbemycin gene cluster during the entire growth period and a moderately high expression level of the nanchangmycin gene cluster during the initial hours that subsequently decreased. However, other gene clusters appear to be silent. The genome-wide analysis of the secondary metabolite gene clusters in S. bingchenggensis, coupled with transcriptional analysis, will facilitate the rational development of high milbemycins-producing strains as well as the discovery of new natural products.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Genoma Bacteriano , Microbiologia Industrial , Streptomyces/genética , Streptomyces/metabolismo , Antibacterianos/biossíntese , Proteínas de Bactérias/química , Cromossomos Bacterianos , Genes Bacterianos , Dados de Sequência Molecular , Família Multigênica , Análise de Sequência com Séries de Oligonucleotídeos , Metabolismo Secundário/genética , Análise de Sequência de DNA , Transdução de Sinais/genética , Streptomyces/química , Streptomyces/classificação
5.
Appl Microbiol Biotechnol ; 97(23): 10091-101, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24077727

RESUMO

Milbemycins A3/A4 are important 16-membered macrolides which have been commercialized and widely used as pesticide and veterinary medicine. However, similar to other milbemycin producers, the production of milbemycins A3/A4 in Streptomyces bingchenggensis is usually accompanied with undesired by-products such as C5-O - methylmilbemycins B2/B3 (α-class) and ß1/ß2 (ß-class) together with nanchangmycin. In order to obtain high yield milbemycins A3/A4-producing strains that produce milbemycins A3/A4 as main components, milD, a putative C5-O-methyltransferase gene of S. bingchenggensis , was biofunctionally investigated by heterologous expression in Escherichia coli . Enzymatic analysis indicated that MilD can catalyze both α-class (A3/A4) and ß-class milbemycins (ß11) into C5-O-methylmilbemycins B2/B3 and ß1, respectively, suggesting little effect of furan ring formed between C6 and C8a on the C5-O-methylation catalyzed by MilD. Deletion of milD gene resulted in the elimination of C5-Omethylmilbemycins B2/B3 and ß1/ß2 together with an increased yield of milbemycins A3/A4 in disruption strain BCJ13. Further disruption of the gene nanLD encoding loading module of polyketide synthase responsible for the biosynthesis of nanchangmycin led to strain BCJ36 that abolished the production of nanchangmycin. Importantly, mutant strain BCJ36 (ΔmilDΔnanLD) produced milbemycins A3/A4 as main secondary metabolites with a yield of 2312 ± 47 µg/ml, which was approximately 74 % higher than that of the initial strain S. bingchenggensis BC-109-6 (1326 ± 37 µg/ml).


Assuntos
Antibacterianos/biossíntese , Éteres/metabolismo , Macrolídeos/metabolismo , Compostos de Espiro/metabolismo , Streptomyces/genética , Streptomyces/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Engenharia Genética , Metiltransferases/genética , Metiltransferases/metabolismo , Policetídeo Sintases/genética , Policetídeo Sintases/metabolismo , Streptomyces/enzimologia
6.
J Agric Food Chem ; 60(5): 1251-7, 2012 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-22242825

RESUMO

In this study, an endophytic Streptomyces sp. neau-D50 with strong antifungal activity against Phytophthora sojae was isolated from healthy soybean root, using an in vitro screening technique. A bioactivity-guided approach was then employed to isolate and determine the chemical identity of bioactive constituents with antifungal activity from strain neau-D50. The structure of the antifungal metabolite was elucidated as borrelidin on the basis of spectral analysis. To our knowledge, this is the first report that borrelidin has strong antifungal activity against dominant race 1 of P. sojae with EC(50) and EC(95) of 0.0056 and 0.026 mg/L, respectively. The values were respectively 62.5- and 262.3-fold lower than those of the commercial fungicide metalaxyl, which has been used to treat soybean seed for the control of P. sojae . The in situ bioassays demonstrated that borrelidin at 10 mg/L reduced P. sojae race 1 lesions on soybean seedlings by 94.72% without affecting root growth. Thus, borrelidin might be a promising candidate for new antifungal agents against P. sojae.


Assuntos
Soja/microbiologia , Streptomyces/metabolismo , Antifúngicos/isolamento & purificação , Antifúngicos/metabolismo , Antifúngicos/farmacologia , Álcoois Graxos/isolamento & purificação , Álcoois Graxos/metabolismo , Álcoois Graxos/farmacologia , Phytophthora/efeitos dos fármacos , Streptomyces/química , Streptomyces/isolamento & purificação
7.
Huan Jing Ke Xue ; 32(9): 2598-603, 2011 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-22165227

RESUMO

Phosphorus recovery as struvite from swine wastewater was carried out. Fourier transform infrared spectroscopy (FTIR), Xray diffraction (XRD) and mass balance analysis were utilized to analyze the species of precipitated minerals under different pH conditions. Results showed that increasing pH from 8.0 to 9.0 resulted in the increase of phosphorus removal efficiency from 85% to 94%. A relatively stable phosphorus removal at 94% was observed at pH 9.0-11.0, whereas a drastic decline to 70% was detected when pH increased to 12.0. The minerals precipitated in the deposits were struvite (MgNH4PO4 x 6H2O), K-struvite (MgKPO4 x 6H2O), amorphous calcium phosphate [Ca3 (PO4 )2 (x) xH2O, ACP] and Mg (OH)2. Struvite was the dominant species in the precipitate at pH 8.0-9.0. Enhancing pH from 9.0 to 10.0 resulted in struvite decline and gave rise to K-struvite and ACP steadily. With regard to highly alkaline conditions at pH above 10, drastic decrease of struvite and rapid increase of ACP and Mg(OH)2 were observed. Maximum concentration of K-struvite was obtained at pH 11.0, following a sharp decline to pH 12.0. Controlling pH between 8.0 and 9.0 could inhibit other minerals formation and obtain the highly pure struvite crystal product.


Assuntos
Compostos de Magnésio/química , Fosfatos/química , Fósforo/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Animais , Precipitação Química , Concentração de Íons de Hidrogênio , Esterco/análise , Fósforo/química , Estruvita , Suínos
8.
Bioorg Med Chem Lett ; 21(18): 5145-8, 2011 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-21840717

RESUMO

A novel macrocyclic lactone (1) was isolated from the fermentation broth of Streptomycesmicroflavus neau3, and the structure was elucidated by extensive spectroscopic analysis. Compound 1 showed high acaricidal activity against adult mites (IC(50)=11.1 µg mL(-1)), and nematocidal activity against Caenorhabditis elegans (IC(50)=17.4 µg mL(-1)), especially the acaricidal activity against mite eggs with an IC(50) of 37.1 µg mL(-1), which was relative higher than that of the commercial acaricide and nematocide milbemycins A(3)/A(4).


Assuntos
Acaricidas/farmacologia , Antinematódeos/farmacologia , Caenorhabditis elegans/efeitos dos fármacos , Lactonas/farmacologia , Compostos Macrocíclicos/farmacologia , Ácaros/efeitos dos fármacos , Acaricidas/química , Acaricidas/isolamento & purificação , Animais , Antinematódeos/química , Antinematódeos/isolamento & purificação , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Fermentação , Inseticidas/química , Inseticidas/isolamento & purificação , Inseticidas/farmacologia , Lactonas/química , Lactonas/isolamento & purificação , Compostos Macrocíclicos/química , Compostos Macrocíclicos/isolamento & purificação , Conformação Molecular , Estereoisomerismo , Streptomyces/química , Streptomyces/metabolismo , Relação Estrutura-Atividade
9.
J Agric Food Chem ; 59(13): 7506-13, 2011 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-21595495

RESUMO

Chlorination can significantly enhance the antioxidant and antitumor activity of genistein. In this paper, genistein, 8-chlorogenistein, and 3',8-dichlorogenistein were selected to investigate the binding to bovine serum albumin (BSA) using fluorescence spectroscopy and circular dichroism (CD). The results showed that chlorination, especially at position 3', had significant effects on the binding constant value of chlorinated genistein derivatives to BSA; however, the binding site and the binding number were slightly affected. The thermodynamic parameters indicated that hydrophobic and electrostatic forces played important roles in the binding process and the enhanced binding affinity mainly associated with the increase of the hydrophobicity caused by the chlorine atom substitution. Furthermore, the CD data demonstrated that the conformation of BSA was slightly altered in the presence of genistein, 8-chlorogenistein, and 3',8-dichlorogenistein, with different reduced α-helix contents. The results obtained herein will be of biological significance in toxicology investigation and genistein derivative drug design.


Assuntos
Genisteína/análogos & derivados , Genisteína/metabolismo , Soroalbumina Bovina/metabolismo , Sítios de Ligação , Dicroísmo Circular , Genisteína/química , Interações Hidrofóbicas e Hidrofílicas , Ligação Proteica , Conformação Proteica , Espectrometria de Fluorescência , Relação Estrutura-Atividade , Termodinâmica
11.
J Bacteriol ; 192(17): 4526-7, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20581206

RESUMO

Streptomyces bingchenggensis is a soil-dwelling bacterium producing the commercially important anthelmintic macrolide milbemycins. Besides milbemycins, the insecticidal polyether antibiotic nanchangmycin and some other antibiotics have also been isolated from this strain. Here we report the complete genome sequence of S. bingchenggensis. The availability of the genome sequence of S. bingchenggensis should enable us to understand the biosynthesis of these structurally intricate antibiotics better and facilitate rational improvement of this strain to increase their titers.


Assuntos
Antibacterianos/biossíntese , Éteres/metabolismo , Genoma Bacteriano , Análise de Sequência de DNA , Compostos de Espiro/metabolismo , Streptomyces/genética , Proteínas de Bactérias/genética , Genoma Bacteriano/genética , Macrolídeos/metabolismo , Dados de Sequência Molecular , Streptomyces/classificação , Streptomyces/metabolismo
12.
Bioresour Technol ; 101(21): 8383-8, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20584599

RESUMO

A bioactivity-guided approach was employed to isolate and determine the chemical identity of bioactive constituents with antifungal activity from Actinoplanes sp. HBDN08. The structure of the antifungal metabolite was elucidated as 5-hydroxyl-5-methyl-2-hexenoic acid on the basis of spectral analysis. This compound showed strong in vitro antifungal activity against Botrytis cinerea, Cladosporium cucumerinum and Corynespora cassiicola, with an IC(50) of 32.45, 27.17, and 30.66 mg/L, respectively; however, it only moderately inhibited hyphal growth of Rhizoctonia solani with an IC(50) of 61.64 mg/L. The in vivo antifungal activity under greenhouse conditions demonstrated that 5-hydroxyl-5-methyl-2-hexenoic acid could effectively control the diseases caused by B. cinerea, C. cucumerinum and C. cassiicola with 71.42%, 78.63% and 65.13% control values at 350 mg/L, respectively. This strong antifungal activity suggests that 5-hydroxyl-5-methyl-2-hexenoic acid might be a promising candidate for new antifungal agents.


Assuntos
Antifúngicos/isolamento & purificação , Antifúngicos/farmacologia , Caproatos/isolamento & purificação , Caproatos/farmacologia , Micromonosporaceae/química , Antifúngicos/química , Caproatos/química , Fungos/efeitos dos fármacos , Concentração Inibidora 50 , Testes de Sensibilidade Microbiana , Micromonosporaceae/genética , Filogenia , Fatores de Tempo
13.
J Hazard Mater ; 176(1-3): 1083-8, 2010 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-19945791

RESUMO

With synthetic swine wastewater, central composite design using response surface methodology was employed to investigate the effects of pH value and concentrations of ammonium, phosphate, magnesium and calcium on phosphorous recovery. P recovery efficiency with the range of 53-99% was observed in the experimental runs. Results showed that magnesium ammonium phosphate were the only crystals, mixed with amorphous calcium precipitates, in the deposits. According to the regression quadratic model, the linear and quadratic terms of PO(4)(3-)-P and Mg had significant effects on the P recovery amount. With regard to the interaction terms, pH x NH(4)(+)-N, PO(4)(3-)-P x Mg, PO(4)(3-)-P x Ca and Mg x Ca showed significant influences. A maximum P recovery amount of 299.25 mg/L was achieved at optimized conditions with pH 9.7, NH(4)(+)-N 456 mg/L, PO(4)(3-)-P 300 mg/L, Mg(2+) 264 mg/L and Ca(2+) 59 mg/L, respectively.


Assuntos
Precipitação Química , Resíduos Industriais/prevenção & controle , Fósforo/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Animais , Animais Domésticos , Compostos de Cálcio , Compostos de Magnésio , Fosfatos , Estruvita , Suínos
14.
J Neurophysiol ; 89(5): 2678-84, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12612013

RESUMO

It has been well established by recording, inactivation, and neuroanatomical studies that the caudate nucleus is important for the control of saccadic eye movements. However, until now, there has been little evidence that the caudate nucleus plays a role in smooth pursuit eye movements. In the present study, we physiologically identified the smooth pursuit subregion of the frontal eye field (FEFsem) and the saccadic subregion of the frontal eye field (FEFsac) in four Cebus monkeys. Anterogradely transported tracers (biotinylated dextran amines and wheat germ aglutinin conjugated to horseradish peroxidase) were then used to determine the efferent connections of the FEFsem to the caudate nucleus and to compare those connections with projections arising in the FEFsac. We observed dense projections from the FEFsem to the head and body of the caudate. The FEFsem and FEFsac terminal fields were of approximately equal density and total area. The region of FEFsem-labeled axon terminals overlapped only slightly with the region of FEFsac-labeled terminals. These results suggest that the caudate nucleus may play an important role in the control of smooth pursuit eye movements via feedback loops involving the basal ganglia and thalamus. Our results further suggest that the basal ganglia circuitry concerned with controlling visual pursuit is physically segregated from that concerned with controlling saccadic eye movements.


Assuntos
Núcleo Caudado/fisiologia , Movimentos Sacádicos/fisiologia , Campos Visuais/fisiologia , Animais , Biotina , Núcleo Caudado/anatomia & histologia , Cebus , Dextranos , Vias Eferentes/fisiologia , Estimulação Elétrica , Lateralidade Funcional/fisiologia , Microeletrodos , Sondas Moleculares , Terminações Pré-Sinápticas/fisiologia , Putamen/fisiologia , Conjugado Aglutinina do Germe de Trigo-Peroxidase do Rábano Silvestre
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