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1.
Environ Sci Technol ; 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-32013402

RESUMO

Plastics waste and microplastics including polyethylene (PE) and polystyrene (PS) have been an environmental concern for years. Recent research has revealed that larvae of Galleria mellonella are capable of biodegrading low density PE film. In this study, we tested the feasibility of enhancing larval survival and the effect of supplementing the co-diet on plastic degradation by feeding the larvae beeswax or wheat bran as a co-diet. Significant mass loss of plastic was observed over a 21-day period, i.e., with respective consumption of 0.88 and 1.95 g by 150 larvae fed only either PS or PE. The formation of C═O and C-O containing functional groups and long chain fatty acids as the metabolic intermediates of plastics in the residual polymers indicated depolymerization and biodegradation. Supplementing beeswax and bran increased the survival rates but decreased the consumption of plastic. The changes in the gut microbiome revealed that Bacillus and Serratia were significantly associated with the PS and PE diets. Beeswax and bran showed different shaping effects on the core gut microbiome of larvae fed the PE and PS. These results suggest that supplementing the co-diet affected the physiological properties of the larvae and plastic biodegradation and shaped the core gut microbiome.

2.
J Hazard Mater ; 388: 122070, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31954307

RESUMO

The emerging antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are increasingly appreciated to be as important as microbial contaminants. This paper focused on UV-activated persulfate (UV/PS), an advanced oxidation process, in removing ARB and ARGs from secondary wastewater effluent. Results showed that the inactivation efficiency of macrolides-resistant bacteria (MRB), sulfonamides-resistant bacteria (SRB), tetracyclines-resistant bacteria (TRB) and quinolones-resistant bacteria (QRB) by UV/PS reached 96.6 %, 94.7 %, 98.0 % and 99.9 % in 10 min, respectively. UV/PS also showed significant removal efficiency on ARGs. The reduction of total ARGs reached 3.84 orders of magnitude in UV/PS which is more than that in UV by 0.56 log. Particularly, the removal of mobile genetic elements (MGE) which might favor the horizontal gene transfer of ARGs among different microbial achieved 76.09 % by UV/PS. High-throughput sequencing revealed that UV/PS changed the microbial community. The proportions of Proteobacteria and Actinobacteria that pose human health risks were 4.25 % and 1.6 % less than UV, respectively. Co-occurrence analyzes indicated that ARGs were differentially contributed by bacterial taxa. In UV/PS system, hydroxyl radical and sulfate radical contributed to the removal of bacteria and ARGs. Our study provided a new method of UV/PS to remove ARGs and ARB for wastewater treatment.

3.
Bioresour Technol ; 297: 122505, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31806513

RESUMO

This study presents a novel approach based on addition of biochar generated from residue of cornstalk left after pretreatment and hydrolysis (RCPH-biochar) to improve hydrogen production from cornstalk hydrolysate. RCPH-biochar at concentration of 15 g L-1 substantially enhanced hydrogen generation during batch tests, with the highest cumulative hydrogen volume (3990 mL L-1) being 1.7 times that without RCPH-biochar. Then, continuous hydrogen production performance demonstrated that RCPH-biochar was capable of retaining biomass in the reactor, at 6 h hydraulic retention time, hydrogen production rate (22.8 mmol H2 L-1 h-1) was tripled compared to the control, meanwhile, glucose and xylose utilization reached to 82.3% and 54.6%, respectively. Overall material balance indicates continuous hydrogen production with RCPH-biochar enabled 63.4% higher cornstalk transfer to H2 and 53.3% more cornstalk utilization. The findings reported is a closed-loop process and is economically and environmentally attractive, which might support comprehensive cornstalk utilization with less energy input in the future.


Assuntos
Hidrogênio , Anaerobiose , Carvão Vegetal , Estudos de Viabilidade , Fermentação
4.
Chin Med J (Engl) ; 132(24): 2934-2940, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31855963

RESUMO

BACKGROUND: The pathogenesis of multiple sclerosis (MS) is mediated primarily by T cells, but most studies of MS and its animal model, experimental autoimmune encephalomyelitis (EAE), have focused on CD4 T cells. The aims of the current study were to determine the pathological interrelationship between CD4 and CD8 autoreactive T cells in MS/EAE. METHODS: Female C57BL/6 mice (n = 20) were induced by myelin oligodendrocyte glycoprotein (MOG)35-55 peptide. At 14 days after immunization, T cells were isolated from the spleen and purified as CD4 and CD8 T cells by using CD4 and CD8 isolation kits, and then the purity was determined by flow cytometric analysis. These cells were stimulated by MOG35-55 peptide and applied to proliferation assays. The interferon-gamma (IFN-γ) and interleukin (IL)-4 secretion of supernatant of cultured CD4 and CD8 T cells were measured by enzyme-linked immunosorbent assays (ELISA). For adoptive transfer, recipient mice were injected with MOG35-55-specific CD8 or CD4 T cells. EAE clinical course was measured by EAE score at 0-5 scale and spinal cord was examined by staining with hematoxylin and eosin and Luxol fast blue staining. RESULTS: CD8CD3 and CD4CD3 cells were 86% and 94% pure of total CD3 cells after CD8/CD4 bead enrichment, respectively. These cells were stimulated by MOG35-55 peptide and applied to proliferation assays. Although the CD8 T cells had a generally lower response to MOG35-55 than CD4 T cells, the response of CD8 T cells was not always dependent on CD4. CD8 T cell secreted less IFN-γ and IL-4 compared with CD4 T cells. EAE was induced in wildtype B6 naïve mice by adoptive transfer of MOG35-55-specific T cells from B6 active-induced EAE (aEAE) mice. A similar EAE score and slight inflammation and demyelination were found in naive B6 mice after transferring of CD8 T cells from immunized B6 mice compared with transfer of CD4 T cells. CONCLUSION: Our data suggest that CD8 autoreactive T cells in EAE have a lower encephalitogenic function but are unique and independent on pathogenic of EAE rather than their CD4 counterparts.

5.
Immunol Lett ; 214: 45-51, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31491433

RESUMO

Melatonin has protective effects against inflammation but its role in epididymitis is unknown. We addressed this in the present study using lipopolysaccharide (LPS)-stimulated sheep epididymal epithelial cells as an in vitro inflammation model. We found that interleukin (IL)-1ß, IL-6, tumor necrosis factor α, and cyclooxygenase (COX)-2 mRNA levels; COX-2 and Toll-like receptor (TLR)-4 protein levels; and nuclear factor (NF)-κB p65 phosphorylation were increased by LPS treatment. These effects were reversed in a dose-dependent manner by melatonin (10-11-10-7 M). Quantitative reverse transcription PCR and immunofluorescence analyses showed that the melatonin receptors MT1 and MT2 were expressed in sheep epididymal epithelial cells. The inhibitory effect of melatonin on inflammation was abrogated by the MT1 and MT2 receptor antagonist luzindole and the MT2 ligand 4-phenyl-2-propanamide tetraldehyde. Thus, melatonin exerted anti-inflammatory effect in epididymal epithelial cells by inhibiting TLR4/NF-κB signaling, suggesting its potential as an effective drug for the treatment of epididymitis in sheep.

6.
Sheng Li Xue Bao ; 71(4): 581-587, 2019 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-31440755

RESUMO

The purpose of this study was to establish a method to record the dynamic process of vascular regeneration and remodeling in rat cerebral ischemic regions. An animal brain window model was established to continuously observe the changes of rat cortical vascular ischemia in vivo, and the model of cerebral ischemia was established by photochemical embolization. Optical coherence tomography (OCT) was performed to record the formation of vascular blockage and the injury and regeneration of small vessels during cerebral ischemia recovery. The results showed that 30 min of laser irradiation could completely block the cortical vessels in rats. Within 24-48 h after ischemia, the degree of brain injury was the greatest, and the number of blood vessels in the ischemic region reached the minimum. Then the blocked blood vessels began to be dredged, and the small blood vessels around the ischemic area began to regenerate. Small blood vessels in the superficial/deep layers of the cortex disappeared significantly after laser irradiation. During 10 d after ischemia, the blocked blood vessels were gradually dredged and recovered. On the 10th day after laser irradiation, a large number of neovascularization appeared in the superficial layer of cortex, but the deep vessels did not recover. These results indicate that the method established in this study can observe the changes of blood vessel in cerebral ischemic region continuously, which lays a foundation for further quantitative study on the dynamics of embolized blood vessels and peripheral capillaries during the recovery of cerebral ischemia.


Assuntos
Isquemia Encefálica , Encéfalo/irrigação sanguínea , Córtex Cerebral/irrigação sanguínea , Regeneração , Animais , Ratos
7.
Clin Endocrinol (Oxf) ; 91(6): 759-769, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31420887

RESUMO

OBJECTIVE: In this study, a genetic risk score (GRS) for the body mass index (BMI) tested and built using a large sample of Chinese individuals aged at least 50 years in southern China. We collected information regarding the participants' weights at 20 years of age and middle age and tested the BMI-GRS effect modes. METHODS: This study involved a prospective study design. The genetic data of the participants in from the Guangzhou Biobank Cohort Study and selected BMI-related single-nucleotide polymorphisms (SNPs) were used to establish the GRS. RESULTS: We included 13 597 participants with 12 SNPs. After adjusting for covariates, the high-GRS group was 36% (95% CI: 25%-48%) and 34% (95% CI: 23%-47%) more likely of being overweight at baseline and follow-up, respectively, and 56% (95% CI: 34%-82%) and 49% (95% CI: 29%-72%) more likely of being obese at baseline and follow-up, respectively, compared with the low-GRS group (P-value for all trends <.05). The RRs for the incidences of metabolically healthy and unhealthy obese (MHO and MUO, respectively) individuals in the high-GRS group were 0.94 (95% CI: 0.65-1.35) and 1.28 (95% CI: 1.00-1.63), respectively. CONCLUSION: High-GRS participants were more likely to be overweight/obese at baseline and follow-up, and this relationship exhibited a dose-response relationship. The GRS was also associated with MUO.

8.
J Cardiovasc Pharmacol ; 74(2): 137-142, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31356543

RESUMO

BACKGROUND: Prophylactic medications are believed to reduce risks of gastrointestinal (GI) bleeding after percutaneous coronary intervention (PCI). However, their true effectiveness in preventing GI bleeding is still unknown. METHODS: The clinical data of 36,870 patients treated with PCI from January 2010 to July 2017 were retrospectively analyzed. The trend in the prophylactic use of mucosal protective agents and proton pump inhibitors was analyzed. RESULTS: A total of 36,870 patients were included with a mean age of 60 ± 18 years. In patients treated with primary PCI for ST-segment elevation myocardial infarction, prophylactic medications were associated with a significantly lower incidence of postprocedure GI bleeding in comparison with no medication (1.072%, 52/4852 vs. 2.747%, 25/910; P < 0.001). In patients with CRUSADE scores >40, prophylactic medications were associated with a significantly lower incidence of postprocedure GI bleeding in comparison with not using prophylactic medications (0.679%, 21/3093 vs. 1.899%, 20/1053; P = 0.001). CONCLUSIONS: Prophylactic medications were associated with significantly lower incidence of postprocedure 30-day GI bleeding in patients with primary PCI for ST-segment elevation myocardial infarction or CRUSADE scores >40.

9.
Environ Pollut ; 252(Pt B): 1142-1153, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252112

RESUMO

Proper management of waste crop residues has been an environmental concern for years. Yellow mealworms (larvae of Tenebrio molitor Linnaeus, 1758) are major insect protein source. In comparison with normal feed wheat bran (WB), we tested five common lignocellulose-rich crop residues as feedstock to rear mealworms, including wheat straw (WS), rice straw (RS), rice bran (RB), rice husk (RH), and corn straw (CS). We then used egested frass for the production of biochar in order to achieve clean production. Except for WS and RH, the crop residues supported mealworms' life activity and growth with consumption of the residues by 90% or higher and degraded lignin, hemicellulose and cellulose over 32 day period. The sequence of degradability of the feedstocks is RS > RB > CS > WS > RH. Egested frass was converted to biochar which was tested for metal removal including Pb(II), Cd(II), Cu(II), Zn(II), and Cr(VI). Biochar via pyrolysis at 600 °C from RS fed frass (FRSBC) showed the best adsorption performance. The adsorption isotherm fits the Langmuir model, and kinetic analysis fits the Pseudo-Second Order Reaction. The heavy metal adsorption process was well-described using the Intra-Particle Diffusion model. Complexation, cation exchange, precipitation, reduction, deposition, and chelation dominated the adsorption of the metals onto FRSBC. The results indicated that crop residues (WS, RS, RB, and CS) can be utilized as supplementary feedstock along with biochar generated from egested frass to rear mealworms and achieve clean production while generating high-quality bioadsorbent for environment remediation and soil conditioning.


Assuntos
Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodos , Metais Pesados/química , Tenebrio/fisiologia , Adsorção , Animais , Biomassa , Dieta , Cinética , Lignina , Metais Pesados/análise , Oryza/metabolismo , Solo/química , Poluentes do Solo/análise , Triticum/metabolismo , Zea mays/metabolismo
10.
Chemosphere ; 234: 893-901, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31252361

RESUMO

Biological phosphorus removal (BPR) is an economical and sustainable processes for the removal of phosphorus (P) from wastewater, achieved by recirculating activated sludge through anaerobic and aerobic (An/Ae) processes. However, few studies have systematically analyzed the optimal hydraulic retention times (HRTs) in anaerobic and aerobic reactions, or whether these are the most appropriate control strategies. In this study, a novel optimization methodology using an improved Q-learning (QL) algorithm was developed, to optimize An/Ae HRTs in a BPR system. A framework for QL-based BPR control strategies was established and the improved Q function, Qt+1(st,st+1)=Qt(st,st+1)+k·[R(st,st+1)+γ·maxatQt(st,st+1)-Qt(st,st+1)] was derived. Based on the improved Q function and the state transition matrices obtained under different HRT step-lengths, the optimum combinations of HRTs in An/Ae processes in any BPR system could be obtained, in terms of the ordered pair combinations of the . Model verification was performed by applying six different influent chemical oxygen demand (COD) concentrations, varying from 150 to 600 mg L-1 and influent P concentrations, varying from 12 to 30 mg L-1. Superior and stable effluent qualities were observed with the optimal control strategies. This indicates that the proposed novel QL-based BPR model performed properly and the derived Q functions successfully realized real-time modelling, with stable optimal control strategies under fluctuant influent loads during wastewater treatment processes.


Assuntos
Algoritmos , Aprendizado de Máquina , Fósforo/isolamento & purificação , Esgotos/microbiologia , Águas Residuárias/química , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos , Metabolismo , Modelos Biológicos , Modelos Teóricos , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação
11.
ACS Appl Mater Interfaces ; 10(44): 38648-38655, 2018 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-30360081

RESUMO

The accurate and rapid quantitative detection of antibodies had a significant influence in controlling and preventing disease or toxin outbreaks. In this work, we first introduce the antibody-powered triplex-DNA nanomachine to release cargo DNA as a substitute target for sensitive electrochemiluminescence (ECL) detection of anti-digoxigenin based on a novel ternary ECL system. It is worth noting that the cargo DNA as a substitute target of antibody can further participate in an enzyme-assisted cycling strand displacement reaction to achieve ECL signal amplification and improve the sensitivity of antibody detection. Additionally, porous palladium nanospheres with a considerable catalytic activity were first applied as a coreaction accelerator to efficiently enhance the intensity of the ECL system of rubrene microblocks as luminophore and dissolved O2 as an endogenous coreactant. With the resultant ternary ECL system as a biosensing platform, a significantly enhanced initial signal was achieved in advance. Then, the ferrocene-labeled quenching probes were employed to reduce initial signal and obtain the low-background signal. Eventually, the cargo DNA made the quenching probes release and recover the signal in the presence of anti-digoxigenin. Thereupon, the wide linear range (0.01-200 nM) and low limit of detection (6.7 pM) were obtained, and this method not only reduces conjugation steps but also provides a sensitive and novel ECL analysis platform for the trace detection of other antibodies and antigen.


Assuntos
Técnicas Biossensoriais , DNA/química , Digoxigenina/isolamento & purificação , Nanoestruturas/química , Anticorpos/química , Digoxigenina/química , Técnicas Eletroquímicas , Luminescência , Medições Luminescentes , Naftacenos/química
12.
Chemosphere ; 212: 262-271, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30145418

RESUMO

Academics researchers and "citizen scientists" from 22 countries confirmed that yellow mealworms, the larvae of Tenebrio molitor Linnaeus, can survive by eating polystyrene (PS) foam. More detailed assessments of this capability for mealworms were carried out by12 sources: five from the USA, six from China, and one from Northern Ireland. All of these mealworms digested PS foam. PS mass decreased and depolymerization was observed, with appearance of lower molecular weight residuals and functional groups indicative of oxidative transformations in extracts from the frass (insect excrement). An addition of gentamycin (30 mg g-1), a bactericidal antibiotic, inhibited depolymerization, implicating the gut microbiome in the biodegradation process. Microbial community analyses demonstrated significant taxonomic shifts for mealworms fed diets of PS plus bran and PS alone. The results indicate that mealworms from diverse locations eat and metabolize PS and support the hypothesis that this capacity is independent of the geographic origin of the mealworms, and is likely ubiquitous to members of this species.


Assuntos
Bactérias/metabolismo , Biodegradação Ambiental , Besouros/metabolismo , Microbioma Gastrointestinal/fisiologia , Larva/metabolismo , Poliestirenos/metabolismo , Animais , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , China , Besouros/crescimento & desenvolvimento , Microbioma Gastrointestinal/efeitos dos fármacos , Gentamicinas/farmacologia , Larva/crescimento & desenvolvimento
13.
Nanoscale ; 10(28): 13310-13314, 2018 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-29987277

RESUMO

Three isomers were prepared by covalently grafting carbazole (Cz) onto spiro[fluorene-9,9'-xanthene] (SFX) at different positions. Due to the complicated and variable roles of molecular segments, an evolution of the corresponding molecular packing mode was realized, accompanied by the change of nanocrystal morphology and photoluminescence properties.

14.
J Diabetes Res ; 2018: 1031939, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30046615

RESUMO

Objective: To investigate the association between the hypertriglyceridemic waist (HTGW) phenotype and prediabetes in Chinese adults aged 40 years and older. Methods: 12757 adults (4101 men and 8656 women) without diabetes or cardiovascular and cerebrovascular diseases, free of using lipid-modified agents, were enrolled in this cross-sectional study. The HTGW phenotype was defined as elevated serum triglyceride concentrations and enlarged waist circumference. A two-hour post 75 g oral glucose tolerance test was performed in all participants. Multiple logistic regression analysis was used to evaluate the relationship of the HTGW phenotype with prediabetes. Results: Individuals with the HTGW phenotype had a higher adjusted odds ratio (OR: 1.70; 95% CI: 1.48-1.95) of prediabetes than those without the phenotype. There existed a strong relationship of the HTGW phenotype with impaired glucose tolerance (IGT) (OR: 1.83; 95% CI: 1.57-2.13), but not with impaired fasting glucose (IFG) (OR: 0.87; 95% CI: 0.65-1.17). Only women with the HTGW phenotype are significantly associated with the combined IFG and IGT (OR: 1.83; 95% CI: 1.28-2.62). Conclusions: The HTGW phenotype was a useful risk indicator and a practical screening tool to benefit in the early diagnosis and intervention for prediabetes, particularly for IGT and the combined IFG and IGT.


Assuntos
Cintura Hipertrigliceridêmica/complicações , Estado Pré-Diabético/complicações , Circunferência da Cintura , Adulto , Idoso , Grupo com Ancestrais do Continente Asiático , China , Estudos Transversais , Feminino , Intolerância à Glucose , Teste de Tolerância a Glucose , Humanos , Cintura Hipertrigliceridêmica/etnologia , Lipídeos/química , Masculino , Pessoa de Meia-Idade , Razão de Chances , Fenótipo , Estado Pré-Diabético/etnologia , Prevalência , Análise de Regressão , Fatores de Risco , Triglicerídeos/sangue
15.
Environ Sci Technol ; 52(11): 6526-6533, 2018 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-29763555

RESUMO

Recent studies have demonstrated the ability for polystyrene (PS) degradation within the gut of mealworms ( Tenebrio molitor). To determine whether plastics may be broadly susceptible to biodegradation within mealworms, we evaluated the fate of polyethylene (PE) and mixtures (PE + PS). We find that PE biodegrades at comparable rates to PS. Mass balances indicate conversion of up 49.0 ± 1.4% of the ingested PE into a putative gas fraction (CO2). The molecular weights ( Mn) of egested polymer residues decreased by 40.1 ± 8.5% in PE-fed mealworms and by 12.8 ± 3.1% in PS-fed mealworms. NMR and FTIR analyses revealed chemical modifications consistent with degradation and partial oxidation of the polymer. Mixtures likewise degraded. Our results are consistent with a nonspecific degradation mechanism. Analysis of the gut microbiome by next-generation sequencing revealed two OTUs ( Citrobacter sp. and Kosakonia sp.) strongly associated with both PE and PS as well as OTUs unique to each plastic. Our results suggest that adaptability of the mealworm gut microbiome enables degradation of chemically dissimilar plastics.


Assuntos
Microbioma Gastrointestinal , Tenebrio , Animais , Larva , Plásticos , Polietileno
16.
Chemosphere ; 191: 979-989, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29145143

RESUMO

Commercial production of polystyrene (PS) -a persistent plastic that is not biodegradable at appreciable rates in most environments-has led to its accumulation as a major contaminant of land, rivers, lakes, and oceans. Recently, however, an environment was identified in which PS is susceptible to rapid biodegradation: the larval gut of Tenebrio molitor Linnaeus (yellow mealworms). In this study, we evaluate PS degradation capabilities of a previously untested strain of T. molitor and assess its survival and PS biodegradation rates for a range of conditions (two simulated food wastes, three temperatures, seven PS waste types). For larvae fed PS alone, the %PS removed in the short (12-15 h) residence time of the mealworm gut gradually increased for 2-3 weeks then stabilized at values up to 65%. Thirty two-day survival rates were >85% versus 54% for unfed larvae. For mealworms fed ∼10% w/w PS and ∼90% bran, an agricultural byproduct, rates of PS degradation at 25 °C nearly doubled compared to mealworms fed PS alone. Polymer residues in the frass showed evidence of partial depolymerization and oxidation. All of the tested PS wastes degraded, with the less dense foams degrading most rapidly. Mealworms fed bran and PS completed all life cycle stages (larvae, pupae, beetles, egg), and the second generation had favorable PS degradation, opening the door for selective breeding.


Assuntos
Biodegradação Ambiental , Larva/metabolismo , Estágios do Ciclo de Vida/efeitos dos fármacos , Poliestirenos/metabolismo , Tenebrio/metabolismo , Animais , Fibras na Dieta/metabolismo , Cinética , Plásticos/metabolismo , Plásticos/toxicidade , Poliestirenos/toxicidade , Fatores de Tempo , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
17.
Artigo em Inglês | MEDLINE | ID: mdl-28717039

RESUMO

Although the de novo folate biosynthesis pathway has been well studied in bacteria, little is known about its regulation. In the present study, the sigB gene in Mycobacterium tuberculosis was deleted. Subsequent drug susceptibility tests revealed that the M. tuberculosis ΔsigB strain was more sensitive to para-aminosalicylic acid (PAS) and sulfamethoxazole. Comparative transcriptional analysis was performed, and downregulation of pabB was observed in the ΔsigB strain, which was further verified by a quantitative reverse transcription-PCR and Western blot assay. Then, the production levels of para-aminobenzoic acid (pABA) were compared between the sigB deletion mutant and wild-type strain, and the results showed that sigB deletion resulted in decreased production of pABA. In addition, SigB was able to recognize the promoter of pabB in vitro Furthermore, we found that deleting pabC also caused increased susceptibility to PAS. Taken together, our data revealed that, in M. tuberculosis, sigB affects susceptibility to antifolates through multiple ways, primarily by regulating the expression of pabB To our knowledge, this is the first report showing that SigB modulates pABA biosynthesis and thus affecting susceptibility to antifolates, which broadens our understanding of the regulation of bacterial folate metabolism and mechanisms of susceptibility to antifolates.


Assuntos
Ácido 4-Aminobenzoico/metabolismo , Ácido Aminossalicílico/farmacologia , Antituberculosos/farmacologia , Proteínas de Bactérias/genética , Mycobacterium tuberculosis/efeitos dos fármacos , Fator sigma/genética , Sulfametoxazol/farmacologia , Ácido Fólico/metabolismo , Deleção de Genes , Liases/genética , Testes de Sensibilidade Microbiana , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/crescimento & desenvolvimento
18.
Bioresour Technol ; 232: 412-416, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28242205

RESUMO

This paper presents the results of an extended ASM2 model for the modeling and calibration of the role of extracellular polymeric substances (EPS) in phosphorus (P) removal in an anaerobic-aerobic process. In this extended ASM2 model, two new components, the bound EPS (XEPS) and the soluble EPS (SEPS), are introduced. Compared with the ASM2, 7.71, 8.53, and 9.28% decreases in polyphosphate (polyP) were observed in the extended ASM2 in three sequencing batch reactors feeding with different COD/P ratios, indicating that 7.71-9.28% of P in the liquid was adsorbed by EPS. Sensitive analysis indicated that, five parameters were the significant influential parameters and had been chosen for further model calibration by using the least square method to simulate by MATLAB. This extended ASM2 has been successfully established to simulate the output variables and provides a useful reference for the mathematic simulations of the role of EPS in biological phosphorus removal process.


Assuntos
Biopolímeros/química , Modelos Teóricos , Fósforo/isolamento & purificação , Adsorção , Aerobiose , Anaerobiose , Biodegradação Ambiental , Simulação por Computador , Cinética , Esgotos
19.
Artigo em Inglês | MEDLINE | ID: mdl-28223385

RESUMO

Co-trimoxazole, a fixed-dose combination of sulfamethoxazole (SMX) and trimethoprim (TMP), has been used for the treatment of bacterial infections since the 1960s. Since it has long been assumed that the synergistic effects between SMX and TMP are the consequence of targeting 2 different enzymes of bacterial folate biosynthesis, 2 genes (pabB and nudB) involved in the folate biosynthesis of Escherichia coli were deleted, and their effects on the susceptibility to antifolates were tested. The results showed that the deletion of nudB resulted in a lag of growth in minimal medium and increased susceptibility to both SMX and TMP. Moreover, deletion of nudB also greatly enhanced the bactericidal effect of TMP. To elucidate the mechanism of how the deletion of nudB affects the bacterial growth and susceptibility to antifolates, 7,8-dihydroneopterin and 7,8-dihydropteroate were supplemented into the growth medium. Although those metabolites could restore bacterial growth, they had no effect on susceptibilities to the antifolates. Reverse mutants of the nudB deletion strain were isolated to further study the mechanism of how the deletion of nudB affects susceptibility to antifolates. Targeted sequencing and subsequent genetic studies revealed that the disruption of the tetrahydromonapterin biosynthesis pathway could reverse the phenotype caused by the nudB deletion. Meanwhile, overexpression of folM could also lead to increased susceptibility to both SMX and TMP. These data suggested that the deletion of nudB resulted in the excess production of tetrahydromonapterin, which then caused the increased susceptibility to antifolates. In addition, we found that the deletion of nudB also resulted in increased susceptibility to both SMX and TMP in Salmonella enterica Since dihydroneopterin triphosphate hydrolase is an important component of bacterial folate biosynthesis and the tetrahydromonapterin biosynthesis pathway also exists in a variety of bacteria, it will be interesting to design new compounds targeting dihydroneopterin triphosphate hydrolase, which may inhibit bacterial growth and simultaneously potentiate the antimicrobial activities of antifolates targeting other components of folate biosynthesis.


Assuntos
Antibacterianos/farmacologia , Proteínas de Escherichia coli/genética , Escherichia coli/efeitos dos fármacos , Antagonistas do Ácido Fólico/farmacologia , Pirofosfatases/genética , Salmonella enterica/efeitos dos fármacos , Combinação Trimetoprima e Sulfametoxazol/farmacologia , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Proteínas de Escherichia coli/metabolismo , Deleção de Genes , Testes de Sensibilidade Microbiana , Neopterina/análogos & derivados , Neopterina/farmacologia , Pterinas/farmacologia , Pirofosfatases/antagonistas & inibidores , Salmonella enterica/genética , Salmonella enterica/crescimento & desenvolvimento , Tetra-Hidrofolato Desidrogenase/metabolismo
20.
J Antibiot (Tokyo) ; 70(3): 285-291, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28074051

RESUMO

Synergies between sulfonamides and other antimicrobial agents have long been reported, but the reason still remains unclear. Previously, Vilchèze et al. found that, sulfamethoxazole (SMX) could potentiate the bacterialcidal activity of isoniazid (INH) and rifampin (RIF) in Mycobacterium tuberculosis. To test if this was also the case in other bacteria, the ability to potentiate bactericidal effect of RIF by SMX was evaluated in Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Mycobacterium smegmatis. And the ability to potentiate bactericidal effect of streptomycin (SM) by SMX was also evaluated in E. coli and M. Smegmatis. Susceptibility tests and drug exposure experiments were performed for RIF and SM in the presence of sub-ICs of SMX. In drug exposure experiments, 10 mg l-1 of 7,8-dihydropteroic acid (DHP) was used to reverse the effect of SMX. In the presence of sub-ICs of SMX, MIC of RIF for E. coli and M. smegmatis decreased 2 and 16 fold, respectively. In the drug exposure experiments, addition of sub-ICs of SMX suppressed the growth of RIF and SM resistant population in a pool of susceptible bacteria, and the effects of SMX could be reversed by DHP. Besides, we also found that, sub-ICs of para-aminosalicylic acid (PAS) could bactericidal effects of INH, RIF and SM in M. tuberculosis. Taken together, our data suggest that, sub-ICs of anti-folates can potentiate bactericidal effects of other antimicrobial agents in various bacteria.


Assuntos
Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Antagonistas do Ácido Fólico/farmacologia , Ácido Aminossalicílico/farmacologia , Antituberculosos/farmacologia , Sinergismo Farmacológico , Escherichia coli/efeitos dos fármacos , Isoniazida/farmacologia , Testes de Sensibilidade Microbiana , Mycobacterium smegmatis/efeitos dos fármacos , Mycobacterium tuberculosis/efeitos dos fármacos , Rifampina/farmacologia , Salmonella typhimurium , Staphylococcus aureus/efeitos dos fármacos , Sulfametoxazol/farmacologia
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