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1.
Injury ; 55(6): 111560, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38729077

RESUMO

INTRODUCTION: To analyze recent literature comparing clinical outcomes of displaced intra-articular calcaneal fractures (DIACF) treated with open reduction and internal fixation using the extensile lateral approach (ELA) vs the minimally invasive sinus tarsi approach (STA), with a focus on wound complications. MATERIALS AND METHODS: A comprehensive literature search was conducted utilizing PubMed, EMBASE, and Cochrane Library databases following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies published between 2013 and 2022, level of evidence (LOE) I-III, head-to-head comparative studies reporting on clinical outcomes after DIACFs treated with ORIF using ELA versus STA, and literature with full-text written in English were included. Data collection included: publication year, study design, number of surgeons, number of participants, demographic data (mean age at time of surgery, percent male, body mass index, medical co-morbidities), preoperative data (mechanism of injury, Sanders classification, time from injury to surgical fixation), intraoperative data, and postoperative clinical and radiographic outcomes (Böhler angle, angle of Gissane, calcaneal height/length/width). RESULTS: A total of 21 articles (4 randomized control trials, 17 cohort studies) comprising of 2086 patients with calcaneal fractures, treated with either ELA (n = 1129) or STA (n = 957) met inclusion criteria. The risk of postoperative wound-related complications (RR 2.82, 95 % CI: 2.00-3.98, I2=27 %) and the risk of reoperation (RR 1.85, 95 % CI: 0.69-5.00, I2=67 %) was higher in ELA patients comparted to STA patients. However, the increased risk of postoperative wound-related complications with an ELA vs. STA was shown to be trending downward in recent publications. The ELA group also experienced longer time to surgery, extended operative times, and prolonged hospital stays when compared to the STA group. Radiographic measurements at final follow-up, including Böhler angle, angle of Gissane, as well as calcaneal height, length, and width, showed no statistically significant differences between the two groups. CONCLUSION: Surgical treatment of calcaneal fractures utilizing the ELA continues to have an increased rate of complications and reoperation when compared to the less invasive STA, yet recent trends in the literature show that this rate is decreasing. Operative treatment of calcaneal fractures via either an ELA or STA can both achieve comparable postoperative radiographic outcomes. LEVEL OF EVIDENCE: Therapeutic Level III.


Assuntos
Calcâneo , Fixação Interna de Fraturas , Humanos , Calcâneo/lesões , Calcâneo/cirurgia , Calcâneo/diagnóstico por imagem , Fixação Interna de Fraturas/métodos , Fixação Interna de Fraturas/efeitos adversos , Complicações Pós-Operatórias/etiologia , Resultado do Tratamento , Infecção da Ferida Cirúrgica/etiologia , Fraturas Intra-Articulares/cirurgia , Fraturas Intra-Articulares/diagnóstico por imagem , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Redução Aberta/métodos , Redução Aberta/efeitos adversos , Fraturas Ósseas/cirurgia
3.
Neurotrauma Rep ; 4(1): 236-250, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37095853

RESUMO

Leukemia inhibitory factor (LIF) is a neuroprotective cytokine that is essential for appropriate glial responses, remyelination, and preservation of neuronal conductance after injury. The intranasal route for delivery of therapeutics to the central nervous system is of particular interest given that it bypasses the blood-brain barrier and peripheral clearance systems. We explored the possibility that LIF might improve neurological function when administered intranasally during the acute phase in a pediatric model of mild traumatic brain injury (mTBI). We tested two doses of LIF and evaluated behavioral outcomes. Here, we show that acute 40-ng intranasal LIF treatment twice a day for 3 days attenuates astrogliosis and microgliosis, protects against axonal damage, significantly improves sensorimotor function, and is well tolerated without detrimental effects on growth. Altogether, our studies provide pre-clinical evidence for the use of acute intranasal LIF treatment as a viable therapeutic for pediatric cases of mTBIs.

4.
Int J Biol Macromol ; 235: 123840, 2023 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-36849073

RESUMO

Utilization of microbial laccases is considered as the cleaner and target specific biocatalytic mechanism for the recovery of cellulose and hemicelluloses from nonfood and wasted agricultural, lignocellulosic biomass (LCB). The extent of lignin removal by laccase depends on the biochemical composition of biomass and the redox potential (E0) of the biocatalyst. Intensive research efforts are going on all over the world for the recognition of appropriate and easily available agricultural lignocellulosic feedstocks to exploit maximally for the production of value-added bioproducts and biofuels. In such circumstances, laccase can play a major role as a leading biocatalyst and potent substitute for chemical based deconstruction of the lignocellulosic materials. The limited commercialization of laccase at an industrial scale has been feasible due to its full working efficiency mostly expressed in the presence of cost intensive redox mediators only. Although, recently there are some reports that came on the mediator free biocatalysis of enzyme but still not considerably explored and neither understood in depth. The present review will address the various research gaps and shortcomings that acted as the big hurdles before the complete exploitation of laccases at an industrial scale. Further, this article also reveals insights on different microbial laccases and their diverse functional environmental conditions that affect the deconstruction process of LCB.


Assuntos
Lacase , Lignina , Biomassa , Lignina/química , Celulose , Biocombustíveis
5.
Front Microbiol ; 13: 844287, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35694290

RESUMO

A thermophilic Geobacillus bacterial strain, WSUCF1 contains different carbohydrate-active enzymes (CAZymes) capable of hydrolyzing hemicellulose in lignocellulosic biomass. We used proteomic, genomic, and bioinformatic tools, and genomic data to analyze the relative abundance of cellulolytic, hemicellulolytic, and lignin modifying enzymes present in the secretomes. Results showed that CAZyme profiles of secretomes varied based on the substrate type and complexity, composition, and pretreatment conditions. The enzyme activity of secretomes also changed depending on the substrate used. The secretomes were used in combination with commercial and purified enzymes to carry out saccharification of ammonia fiber expansion (AFEX)-pretreated corn stover and extractive ammonia (EA)-pretreated corn stover. When WSUCF1 bacterial secretome produced at different conditions was combined with a small percentage of commercial enzymes, we observed efficient saccharification of EA-CS, and the results were comparable to using a commercial enzyme cocktail (87% glucan and 70% xylan conversion). It also opens the possibility of producing CAZymes in a biorefinery using inexpensive substrates, such as AFEX-pretreated corn stover and Avicel, and eliminates expensive enzyme processing steps that are used in enzyme manufacturing. Implementing in-house enzyme production is expected to significantly reduce the cost of enzymes and biofuel processing cost.

6.
BMJ Case Rep ; 15(4)2022 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-35450872

RESUMO

There is a bidirectional relationship between hepatitis C and type 2 diabetes. The risk for developing type 2 diabetes is increased in patients with chronic hepatitis C virus (HCV) infection-with the prevalence of diabetes ranging from 13% to 33%. This is likely underpinned by insulin resistance. Type 2 diabetes may also be a predisposing factor for HCV infection. The new non-interferon-based therapeutic regimens for hepatitis C have transformed care and can eradicate disease. In this report, we show how such a regimen eradicated viral load, improved hepatocellular blood markers and significantly improved dysglycaemia, such that all glucose-lowering medication could be stopped.


Assuntos
Diabetes Mellitus Tipo 2 , Hepatite C Crônica , Hepatite C , Antivirais/uso terapêutico , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/epidemiologia , Hepacivirus/genética , Hepatite C/tratamento farmacológico , Hepatite C Crônica/complicações , Hepatite C Crônica/tratamento farmacológico , Humanos , Insulina/uso terapêutico
7.
J Intensive Care Soc ; 23(1): 34-43, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37593533

RESUMO

Background: In March 2020, Covid-19 secondary to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was declared a global pandemic. Methods: This retrospective observational study included patients with Covid-19, managed in a single intensive care unit (ICU). We collected data on patient characteristics, laboratory and radiological findings and ICU management. Data are reported as median (interquartile range). Binary logistic regression modelling was used to identify variables at ICU admission associated with mortality. Results: 85 patients (age 57.3 years [49.4-64.2], 75.3% male) were followed up for 34 days (26-40). The commonest comorbidities were hypertension (51.8%), obesity (48.7%), and type 2 diabetes (31.8%). Covid-19 presented with shortness of breath (89.4%), fever (82.4%), and cough (81.2%), first noted 8 days (6-10) prior to ICU admission. PaO2/FiO2-ratios at ICU admission were 8.28 kPa (7.04-11.7). Bilateral infiltrates on chest X-ray, lymphopenia, and raised C-reactive protein and ferritin were typical. 81.2% received invasive mechanical ventilation (IMV). Acute kidney injury occurred in 62.4% with renal replacement therapy required in 20.0%. By the end of the follow-up period, 44.7% had died, 30.6% had been discharged from hospital, 14.1% had been discharged from ICU but remained in hospital and 10.6% remained in ICU. ICU length of stay was 14 days (9-23). Age was the only variable at admission which was associated with mortality. PaO2/FiO2-ratio, driving pressure and peak ferritin and neutrophil count over the first 72-hours of IMV all correlated with mortality. Conclusions: We report the clinical characteristics, ICU practices and outcomes of a South London cohort with Covid-19, and have identified factors which correlate with mortality. By sharing our insight, we hope to further understanding of this novel disease.

8.
Biotechnol Biofuels ; 13: 137, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32782473

RESUMO

BACKGROUND: Trichoderma reesei is one of the best-known cellulolytic organisms, producing large quantities of a complete set of extracellular cellulases and hemicellulases for the degradation of lignocellulosic substances. Hence, T. reesei is a biotechnically important host and it is used commercially in enzyme production, of both native and foreign origin. Many strategies for producing enzymes in T. reesei rely on the cbh1 and other cellulase gene promoters for high-level expression and these promoters require induction by sophorose, lactose or other inducers for high productivity during manufacturing. RESULTS: We described an approach for producing high levels of secreted proteins by overexpression of a transcription factor ACE3 in T. reesei. We refined the ace3 gene structure and identified specific ACE3 variants that enable production of secreted cellulases and hemicellulases on glucose as a sole carbon source (i.e., in the absence of an inducer). These specific ACE3 variants contain a full-length Zn2Cys6 binuclear cluster domain at the N-terminus and a defined length of truncations at the C-terminus. When expressed at a moderate level in the fungal cells, the ACE3 variants can induce high-level expression of cellulases and hemicellulases on glucose (i.e., in the absence of an inducer), and further improve expression on lactose or glucose/sophorose (i.e., in the presence of an inducer). Finally, we demonstrated that this method is applicable to industrial strains and fermentation conditions, improving protein production both in the absence and in the presence of an inducer. CONCLUSIONS: This study demonstrates that overexpression of ACE3 variants enables a high level of protein production in the absence of an inducer, and boosts protein production in the presence of an inducer. It is an efficient approach to increase protein productivity and to reduce manufacturing costs.

9.
Biotechnol Biofuels ; 12: 213, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31516552

RESUMO

BACKGROUND: In this work, three pretreatments under investigation at the DOE Bioenergy Research Centers (BRCs) were subjected to a side-by-side comparison to assess their performance on model bioenergy hardwoods (a eucalyptus and a hybrid poplar). These include co-solvent-enhanced lignocellulosic fractionation (CELF), pretreatment with an ionic liquid using potentially biomass-derived components (cholinium lysinate or [Ch][Lys]), and two-stage Cu-catalyzed alkaline hydrogen peroxide pretreatment (Cu-AHP). For each of the feedstocks, the pretreatments were assessed for their impact on lignin and xylan solubilization and enzymatic hydrolysis yields as a function of enzyme loading. Lignins recovered from the pretreatments were characterized for polysaccharide content, molar mass distributions, ß-aryl ether content, and response to depolymerization by thioacidolysis. RESULTS: All three pretreatments resulted in significant solubilization of lignin and xylan, with the CELF pretreatment solubilizing the majority of both biopolymer categories. Enzymatic hydrolysis yields were shown to exhibit a strong, positive correlation with the lignin solubilized for the low enzyme loadings. The pretreatment-derived solubles in the [Ch][Lys]-pretreated biomass were presumed to contribute to inhibition of enzymatic hydrolysis in the eucalyptus as a substantial fraction of the pretreatment liquor was carried forward into hydrolysis for this pretreatment. The pretreatment-solubilized lignins exhibited significant differences in polysaccharide content, molar mass distributions, aromatic monomer yield by thioacidolysis, and ß-aryl ether content. Key trends include a substantially higher polysaccharide content in the lignins recovered from the [Ch][Lys] pretreatment and high ß-aryl ether contents and aromatic monomer yields from the Cu-AHP pretreatment. For all lignins, the 13C NMR-determined ß-aryl ether content was shown to be correlated with the monomer yield with a second-order functionality. CONCLUSIONS: Overall, it was demonstrated that the three pretreatments highlighted in this study demonstrated uniquely different functionalities in reducing biomass recalcitrance and achieving higher enzymatic hydrolysis yields for the hybrid poplar while yielding a lignin-rich stream that may be suitable for valorization. Furthermore, modification of lignin during pretreatment, particularly cleavage of ß-aryl ether bonds, is shown to be detrimental to subsequent depolymerization.

11.
Bioresour Technol ; 266: 232-241, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29982043

RESUMO

The aim of the present work was to use a thermophilic consortium for H2 production using lignocellulosic biomass in a single pot. The thermophilic consortium, growing at 60 °C utilized both glucose and xylose, making it an ideal source of microbes capable of utilizing and fermenting both hexose and pentose sugars. The optimization of pH, temperature, and substrate concentration increased the H2 production from 1.07 mmol H2/g of prairie cordgrass (PCG) to 2.2 mmol H2/g PCG by using the thermophilic consortium. A sequential cultivation of a thermostable lignocellulolytic enzyme producing strain Geobacillus sp. strain WSUCF1 (aerobic) with the thermophilic consortium (anaerobic) further increased H2 production with PCG 3-fold (3.74 mmol H2/g PCG). A single pot sequential culturing of aerobic and anaerobic microbes can be sustainable and advantageous for industrial scale production of biofuels.


Assuntos
Biocombustíveis , Pradaria , Xilose , Biomassa , Fermentação , Geobacillus , Hidrogênio
12.
J Ind Microbiol Biotechnol ; 45(9): 795-801, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29915996

RESUMO

Livestock and fish farming are rapidly growing industries facing the simultaneous pressure of increasing production demands and limited protein required to produce feed. Bacteria that can convert low-value non-food waste streams into singe cell protein (SCP) present an intriguing route for rapid protein production. The oleaginous bacterium Rhodococcus opacus serves as a model organism for understanding microbial lipid production. SCP production has not been explored using an organism from this genus. In the present research, R. opacus strains DSM 1069 and PD630 were fed three agro-waste streams: (1) orange pulp, juice, and peel; (2) lemon pulp, juice, and peel; and (3) corn stover effluent, to determine if these low-cost substrates would be suitable for producing a value-added product, SCP for aquafarming or livestock feed. Both strains used agro-waste carbon sources as a growth substrate to produce protein-rich cell biomass suggesting that that R. opacus can be used to produce SCP using agro-wastes as low-cost substrates.


Assuntos
Proteínas Alimentares/metabolismo , Rhodococcus/metabolismo , Biomassa , Produtos Agrícolas/química , Fermentação
13.
Biotechnol Biofuels ; 11: 143, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29796084

RESUMO

BACKGROUND: When applied to recalcitrant lignocellulosic feedstocks, multi-stage pretreatments can provide more processing flexibility to optimize or balance process outcomes such as increasing delignification, preserving hemicellulose, and maximizing enzymatic hydrolysis yields. We previously reported that adding an alkaline pre-extraction step to a copper-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment process resulted in improved sugar yields, but the process still utilized relatively high chemical inputs (catalyst and H2O2) and enzyme loadings. We hypothesized that by increasing the temperature of the alkaline pre-extraction step in water or ethanol, we could reduce the inputs required during Cu-AHP pretreatment and enzymatic hydrolysis without significant loss in sugar yield. We also performed technoeconomic analysis to determine if ethanol or water was the more cost-effective solvent during alkaline pre-extraction and if the expense associated with increasing the temperature was economically justified. RESULTS: After Cu-AHP pretreatment of 120 °C NaOH-H2O pre-extracted and 120 °C NaOH-EtOH pre-extracted biomass, approximately 1.4-fold more total lignin was solubilized (78% and 74%, respectively) compared to the 30 °C NaOH-H2O pre-extraction (55%) carried out in a previous study. Consequently, increasing the temperature of the alkaline pre-extraction step to 120 °C in both ethanol and water allowed us to decrease bipyridine and H2O2 during Cu-AHP and enzymes during hydrolysis with only a small reduction in sugar yields compared to 30 °C alkaline pre-extraction. Technoeconomic analysis indicated that 120 °C NaOH-H2O pre-extraction has the lowest installed ($246 million) and raw material ($175 million) costs compared to the other process configurations. CONCLUSIONS: We found that by increasing the temperature of the alkaline pre-extraction step, we could successfully lower the inputs for pretreatment and enzymatic hydrolysis. Based on sugar yields as well as capital, feedstock, and operating costs, 120 °C NaOH-H2O pre-extraction was superior to both 120 °C NaOH-EtOH and 30 °C NaOH-H2O pre-extraction.

14.
Biotechnol Biofuels ; 9: 34, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26862348

RESUMO

BACKGROUND: Strategies to improve copper-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment of hybrid poplar were investigated. These improvements included a combination of increasing hydrolysis yields, while simultaneously decreasing process inputs through (i) more efficient utilization of H2O2 and (ii) the addition of an alkaline extraction step prior to the metal-catalyzed AHP pretreatment. We hypothesized that utilizing this improved process could substantially lower the chemical inputs needed during pretreatment. RESULTS: Hybrid poplar was pretreated utilizing a modified process in which an alkaline extraction step was incorporated prior to the Cu-AHP treatment step and H2O2 was added batch-wise over the course of 10 h. Our results revealed that the alkaline pre-extraction step improved both lignin and xylan solubilization, which ultimately led to improved glucose (86 %) and xylose (95 %) yields following enzymatic hydrolysis. An increase in the lignin solubilization was also observed with fed-batch H2O2 addition relative to batch-only addition, which again resulted in increased glucose and xylose yields (77 and 93 % versus 63 and 74 %, respectively). Importantly, combining these strategies led to significantly improved sugar yields (96 % glucose and 94 % xylose) following enzymatic hydrolysis. In addition, we found that we could substantially lower the chemical inputs (enzyme, H2O2, and catalyst), while still maintaining high product yields utilizing the improved Cu-AHP process. This pretreatment also provided a relatively pure lignin stream consisting of ≥90 % Klason lignin and only 3 % xylan and 2 % ash following precipitation. Two-dimensional heteronuclear single-quantum coherence (2D HSQC) NMR and size-exclusion chromatography demonstrated that the solubilized lignin was high molecular weight (Mw ≈ 22,000 Da) and only slightly oxidized relative to lignin from untreated poplar. CONCLUSIONS: This study demonstrated that the fed-batch, two-stage Cu-AHP pretreatment process was effective in pretreating hybrid poplar for its conversion into fermentable sugars. Results showed sugar yields near the theoretical maximum were achieved from enzymatically hydrolyzed hybrid poplar by incorporating an alkaline extraction step prior to pretreatment and by efficiently utilizing H2O2 during the Cu-AHP process. Significantly, this study reports high sugar yields from woody biomass treated with an AHP pretreatment under mild reaction conditions.

15.
Biotechnol Biofuels ; 8: 123, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26300970

RESUMO

BACKGROUND: Alkaline hydrogen peroxide pretreatment catalyzed by Cu(II) 2,2'-bipyridine complexes has previously been determined to substantially improve the enzymatic hydrolysis of woody plants including hybrid poplar as a consequence of moderate delignification. In the present work, cell wall morphological and lignin structural changes were characterized for this pretreatment approach to gain insights into pretreatment outcomes and, specifically, to identify the extent and nature of lignin modification. RESULTS: Through TEM imaging, this catalytic oxidation process was shown to disrupt cell wall layers in hybrid poplar. Cu-containing nanoparticles, primarily in the Cu(I) oxidation state, co-localized with the disrupted regions, providing indirect evidence of catalytic activity whereby soluble Cu(II) complexes are reduced and precipitated during pretreatment. The concentration of alkali-soluble polymeric and oligomeric lignin was substantially higher for the Cu-catalyzed oxidative pretreatment. This alkali-soluble lignin content increased with time during the catalytic oxidation process, although the molecular weight distributions were unaltered. Yields of aromatic monomers (including phenolic acids and aldehydes) were found to be less than 0.2 % (wt/wt) on lignin. Oxidation of the benzylic alcohol in the lignin side-chain was evident in NMR spectra of the solubilized lignin, whereas minimal changes were observed for the pretreatment-insoluble lignin. CONCLUSIONS: These results provide indirect evidence for catalytic activity within the cell wall. The low yields of lignin-derived aromatic monomers, together with the detailed characterization of the pretreatment-soluble and pretreatment-insoluble lignins, indicate that the majority of both lignin pools remained relatively unmodified. As such, the lignins resulting from this process retain features closely resembling native lignins and may, therefore, be amenable to subsequent valorization.

16.
Artigo em Inglês | MEDLINE | ID: mdl-26137456

RESUMO

Efficient enzymatic hydrolysis of lignocellulose to fermentable sugars requires a complete repertoire of biomass deconstruction enzymes. Hemicellulases play an important role in hydrolyzing hemicellulose component of lignocellulose to xylooligosaccharides and xylose. Thermostable xylanases have been a focus of attention as industrially important enzymes due to their long shelf life at high temperatures. Geobacillus sp. strain WSUCF1 produced thermostable xylanase activity (crude xylanase cocktail) when grown on xylan or various inexpensive untreated and pretreated lignocellulosic biomasses such as prairie cord grass and corn stover. The optimum pH and temperature for the crude xylanase cocktail were 6.5 and 70°C, respectively. The WSUCF1 crude xylanase was found to be highly thermostable with half-lives of 18 and 12 days at 60 and 70°C, respectively. At 70°C, rates of xylan hydrolysis were also found to be better with the WSUCF1 secretome than those with commercial enzymes, i.e., for WSUCF1 crude xylanase, Cellic-HTec2, and AccelleraseXY, the percent xylan conversions were 68.9, 49.4, and 28.92, respectively. To the best of our knowledge, WSUCF1 crude xylanase cocktail is among the most thermostable xylanases produced by thermophilic Geobacillus spp. and other thermophilic microbes (optimum growth temperature ≤70°C). High thermostability, activity over wide range of temperatures, and better xylan hydrolysis than commercial enzymes make WSUCF1 crude xylanase suitable for thermophilic lignocellulose bioconversion processes.

17.
BMC Biotechnol ; 14: 963, 2014 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-25532585

RESUMO

BACKGROUND: Complete enzymatic hydrolysis of xylan to xylose requires the action of endoxylanase and ß-xylosidase. ß-xylosidases play an important part in hydrolyzing xylo-oligosaccharides to xylose. Thermostable ß-xylosidases have been a focus of attention as industrially important enzymes due to their long shelf life and role in the relief of end-product inhibition of xylanases caused by xylo-oligosaccharides. Therefore, a highly thermostable ß-xylosidase with high specific activity has significant potential in lignocellulose bioconversion. RESULTS: A gene encoding a highly thermostable GH39 ß-xylosidase was cloned from Geobacillus sp. strain WSUCF1 and expressed in Escherichia coli. Recombinant ß-xylosidase was active over a wide range of temperatures and pH with optimum temperature of 70 °C and pH 6.5. It exhibited very high thermostability, retaining 50% activity at 70 °C after 9 days. WSUCF1 ß-xylosidase is more thermostable than ß-xylosidases reported from other thermophiles (growth temperature ≤ 70 °C). Specific activity was 133 U/mg when incubated with p-nitrophenyl xylopyranoside, with Km and Vmax values of 2.38 mM and 147 U/mg, respectively. SDS-PAGE analysis indicated that the recombinant enzyme had a mass of 58 kDa, but omitting heating prior to electrophoresis increased the apparent mass to 230 kDa, suggesting the enzyme exists as a tetramer. Enzyme exhibited high tolerance to xylose, retained approximately 70% of relative activity at 210 mM xylose concentration. Thin layer chromatography showed that the enzyme had potential to convert xylo-oligomers (xylobiose, triose, tetraose, and pentaose) into fermentable xylose. WSUCF1 ß-xylosidase along with WSUCF1 endo-xylanase synergistically converted the xylan into fermentable xylose with more than 90% conversion. CONCLUSIONS: Properties of the WSUCF1 ß-xylosidase i.e. high tolerance to elevated temperatures, high specific activity, conversion of xylo-oligomers to xylose, and resistance to inhibition from xylose, make this enzyme potentially suitable for various biotechnological applications.


Assuntos
Proteínas de Bactérias/química , Geobacillus/enzimologia , Xilosidases/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Estabilidade Enzimática , Geobacillus/química , Geobacillus/genética , Temperatura Alta , Concentração de Íons de Hidrogênio , Cinética , Lignina/metabolismo , Peso Molecular , Xilose/metabolismo , Xilosidases/genética , Xilosidases/metabolismo
18.
Bioresour Technol ; 165: 314-8, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24725385

RESUMO

A gene encoding a GH10 endo-xylanase from Geobacillus sp. WSUCF1 was cloned and expressed in Escherichia coli. Recombinant endo-xylanase (37kDa) exhibited high specific activity of 461.0U/mg of protein. Endo-xylanase was optimally active on birchwood xylan at 70°C and pH 6.5. The endo-xylanase was found to be highly thermostable at 50 and 60°C, retaining 82% and 50% of its original activity, respectively, after 60h. High xylan conversions (92%) were obtained with oat-spelt xylan hydrolysis. Higher glucan and xylan conversions were obtained on AFEX-treated corn stover with an enzyme cocktail containing WSUCF1 endo-xylanase (71% and 47%) as compared to enzyme cocktail containing commercial fungal endo-xylanase (64% and 41%). High specific activity, active at high pH's, wide substrate specificity, and higher hydrolytic activity on recalcitrant lignocellulose, make this endo-xylanase a suitable candidate for biofuel and bioprocess industries.


Assuntos
Endo-1,4-beta-Xilanases/metabolismo , Geobacillus/enzimologia , Temperatura , Avena/metabolismo , Sequência de Bases , Betula/metabolismo , Clonagem Molecular , Eletroforese em Gel de Poliacrilamida , Estabilidade Enzimática , Fungos/enzimologia , Hidrólise , Lignina/metabolismo , Filogenia , Proteínas Recombinantes/metabolismo , Xilanos/metabolismo
19.
Front Microbiol ; 4: 18, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23919089

RESUMO

Eight fermentative bacterial strains were isolated from mixed enrichment cultures of a composite soil sample collected at 1.34 km depth from the former Homestake gold mine in Lead, SD, USA. Phylogenetic analysis of their 16S rRNA gene sequences revealed that these isolates were affiliated with the phylum Firmicutes belonging to genera Bacillus and Clostridium. Batch fermentation studies demonstrated that isolates had the ability to ferment glucose, xylose, or glycerol to industrially valuable products such as ethanol and 1,3-propanediol (PDO). Ethanol was detected as the major fermentation end product in glucose-fermenting cultures at pH 10 with yields of 0.205-0.304 g of ethanol/g of glucose. While a xylose-fermenting strain yielded 0.189 g of ethanol/g of xylose and 0.585 g of acetic acid/g of xylose at the end of fermentation. At pH 7, glycerol-fermenting isolates produced PDO (0.323-0.458 g of PDO/g of glycerol) and ethanol (0.284-0.350 g of ethanol/g of glycerol) as major end products while acetic acid and succinic acid were identified as minor by-products in fermentation broths. These results suggest that the deep biosphere of the former Homestake gold mine harbors bacterial strains which could be used in bio-based production of ethanol and PDO.

20.
Genome Announc ; 1(4)2013 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-23950119

RESUMO

Geobacillus sp. strain WSUCF1 is a thermophilic spore-forming member of the phylum Firmicutes, isolated from a soil sample collected from the compost facility. We report the draft genome sequence of this isolate with an estimated genome size of 3.4 Mb. The genome sequence of this isolate revealed several genes encoding glycoside hydrolases, making it a potential candidate for plant biomass degradation.

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