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2.
Environ Res ; 244: 117879, 2024 Mar 01.
Article in English | MEDLINE | ID: mdl-38086503

ABSTRACT

Biosurfactants are eco-friendly compounds with unique properties and promising potential as sustainable alternatives to chemical surfactants. The current review explores the multifaceted nature of biosurfactant production and applications, highlighting key fermentative parameters and microorganisms able to convert carbon-containing sources into biosurfactants. A spotlight is given on biosurfactants' obstacles in the global market, focusing on production costs and the challenges of large-scale synthesis. Innovative approaches to valorizing agro-industrial waste were discussed, documenting the utilization of lignocellulosic waste, food waste, oily waste, and agro-industrial wastewater in the segment. This strategy strongly contributes to large-scale, cost-effective, and environmentally friendly biosurfactant production, while the recent advances in waste valorization pave the way for a sustainable society.


Subject(s)
Industrial Waste , Refuse Disposal , Food , Fermentation , Surface-Active Agents/chemistry
3.
BMC Womens Health ; 23(1): 96, 2023 03 09.
Article in English | MEDLINE | ID: mdl-36894908

ABSTRACT

BACKGROUND: Cervical cancer is a major concern to women's health, being the fourth most common cancer worldwide. A great percentage of these cancer is consequence of an HPV infection, namely from specific genotypes such as 16/18. Portuguese screening program subjects women to a reflex cytology triage every 5 years. Aptima® HPV is a screening test which presents better specificity than other tests which are used in Portugal (Hybrid Capture® 2 and Cobas® 4800) and still have a comparable sensitivity. The present study aims to estimate the number of diagnostic tests and costs that are avoided using Aptima® HPV compared to the use of two other tests, Hybrid Capture® 2 and Cobas® 4800, within the cervical cancer screening programme in Portugal. METHODS: A model, consisting of a decision-tree, was developed to represent the full Portuguese screening program for cervical cancer. This model is used to compare the costs resulting from using Aptima® HPV test versus the other tests used in Portugal, during 2 years. Other outcomes such as the number of additional tests and exams were also computed. This comparison considers the performance of each test (sensitivity and specificity) and assumes an equal price for every test compared. RESULTS: Cost savings resulting from the use of Aptima® HPV are estimated at approximately €382 million versus Hybrid Capture® 2 and €2.8 million versus Cobas® 4800. Moreover, Aptima® HPV prevents 265,443 and 269,856 additional tests and exams when compared with Hybrid Capture® 2 and Cobas® 4800. CONCLUSIONS: The use of Aptima® HPV resulted in lower costs as well as less additional test and exams. These values result from the greater specificity of Aptima® HPV, which signals less false positive cases and consequently avoids carrying out additional tests.


Subject(s)
Papillomavirus Infections , Uterine Cervical Dysplasia , Uterine Cervical Neoplasms , Female , Humans , Uterine Cervical Neoplasms/diagnosis , Uterine Cervical Dysplasia/diagnosis , Papillomavirus Infections/complications , Papillomavirus Infections/diagnosis , Portugal , Early Detection of Cancer/methods , Sensitivity and Specificity , Papillomaviridae/genetics , DNA, Viral/genetics
4.
Appl Biochem Biotechnol ; 195(1): 386-400, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36083431

ABSTRACT

The use of non-conventional carbon sources for biosurfactant-producing microorganisms is a promising alternative in fermentation to substitute costly substrates. So, the current research used pineapple peel as a cost-effective and renewable substrate because of its rich composition in minerals and sugars and high availability. Following a 22 full factorial design, a bacterial strain of Bacillus subtilis produced biosurfactants in fermentative media containing different concentrations of glucose and concentrated pineapple peel juice (CPPJ). The influence of these two independent variables was evaluated according to three different responses: surface tension reduction rate (STRR), emulsification index (EI24), and concentration of semi-purified biosurfactant (SPB). The maximum value for STRR (57.63%) was obtained in media containing 0.58% glucose (w/v) and 5.82% CPPJ (v/v), while the highest EI24 response (58.60%) was observed at 2% glucose (w/v) and 20% CPPJ (v/v) and maximum SPB (1.28 g/L) at 3.42% glucose (w/v) and 34.18% CPPJ (v/v). Statistical analysis indicated that the CPPJ variable mostly influenced the STRR and SPB responses, whereas the EI24 was significantly influenced by pineapple peel juice and glucose contents.


Subject(s)
Ananas , Research Design , Surface-Active Agents/chemistry , Bacillus subtilis , Glucose , Surface Tension
5.
Prep Biochem Biotechnol ; 52(2): 123-134, 2022.
Article in English | MEDLINE | ID: mdl-34081569

ABSTRACT

The reuse of agro-industrial waste has been a recurring issue since the 20th century. With a composition rich in carbohydrates and because of the massive amount of residue produced daily all over the world, corncob became a low-cost and suitable substrate to produce high added-value compounds. Biosurfactants are bioproducts of versatile applications due to their chemical structure with hydrophilic and hydrophobic regions. The current work performed a bibliometric analysis to identify research related to the synthesis of biosurfactants using corncob as substrate. Despite the high availability of corncobs, only nine articles were found in Scopus and Web of Science using different pretreatment processes and microorganisms. After an initial screening, data regarding research organizations, scientific journals, citations, countries, institutions, and keywords were analyzed. Results indicated that corncobs were also used to produce enzymes, adsorbents, activated carbon, and furfural. The presented evaluation updated the status of art, identifying a serious need for more research, especially because of corncob's high potential to provide fermentable sugars and the wide range of variables influencing fermentation processes that still need to be studied. A future association of this low-cost substrate with other methods can result in a promising scenario for technology transference.


Subject(s)
Bibliometrics , Surface-Active Agents/metabolism , Zea mays/metabolism , Fermentation
6.
Trab. Educ. Saúde (Online) ; 20: e001154200, 2022.
Article in Portuguese | LILACS | ID: biblio-1410270

ABSTRACT

Resumo Este ensaio se dirige a um campo lacunar na crítica da economia política: o estudo e a disputa da noção de pessoa no laço social capitalista. Com esse intento, trazemos 'o indivíduo' ao foco, defendendo a ideia de que ele configura uma instituição capitalista, isto é, uma regra de pensamento sobre si e sobre os outros que dá consistência à sociedade. Mostramos, então, que essa consistência pode ser percebida na própria análise que Marx faz do capitalismo, uma vez que o preenchimento histórico do sentido do trabalho e a lógica dos conteúdos da mercadoria exigem a produção de sujeitos essencialmente heterônomos, submissos e eivados pela desigualdade. O indivíduo é, assim, reconfigurado, posto no lugar de uma solução de compromisso que propaga um discurso oposto: o de que nossa individualidade é uma marca aparente de autonomia, independência, igualdade e liberdade.


Abstract This essay addresses a lacunar field in the critique of political economy: the study and dispute of the notion of person in the capitalist social bond. With this intention, we bring 'the individual' to focus, defending the idea that he or she configures a capitalist institution, that is, a rule of thought about the self and the other that gives consistency to society. We show, then, that this consistency can be perceived in Marx's own analysis of capitalism, since the historical fulfillment of the meaning of labor and the logic of the contents of the commodity require the production of essentially heteronomous subjects, submissive and driven by inequality. The individual is thus reconfigured, put in the place of a compromise solution that propagates an opposite discourse: that our individuality is an apparent mark of autonomy, independence, equality and freedom.


Resumen Este ensayo se dirige hacia un campo abierto en la crítica de la economía política: el estudio y disputa de la noción de persona en el vínculo social capitalista. Con esta intención, enfocamos al 'individuo', defendiendo la idea de que el configura una institución capitalista, es decir, una regla de pensamiento sobre sí mismo y sobre los demás que da consistencia a la sociedad. Mostramos, entonces, que esta consistencia puede percibirse en el propio análisis del capitalismo de Marx, ya que el cumplimiento histórico del sentido del trabajo y la lógica de los contenidos de la mercancía requieren la producción de sujetos esencialmente heterónomos, sumisos y marcados por la desigualdad. El individuo es así reconfigurado, puesto en el lugar de una solución de compromiso que propaga un discurso opuesto: el de que nuestra individualidad es una marca aparente de autonomía, independencia, igualdad y libertad.


Subject(s)
Individuality
7.
Environ Sci Pollut Res Int ; 28(48): 68957-68971, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34282549

ABSTRACT

The large pineapple's consumption and processing have generated a massive amount of waste yearly, which requires adequate treatment measures to avoid damages to the environment. Pineapple peel is one of the main residues obtained from this fruit and a promising strategy to take advantage of its potential is using it for biosurfactant production due to the peel's rich composition in fermentable sugars and nutrients, such as potassium and magnesium that favor the Bacillus subtilis growth and biosurfactant excretion as well. The current research performed a central composite design (CCD) with four independent variables (glucose, pineapple peel, potassium, and magnesium), evaluating substrates' influence on the surface tension reduction rate (STRR) and the emulsification index (EI24). The results indicated that pineapple peel has the necessary potential to act as a partial substitute for glucose and salt nutrients, minimizing the costs of supplementing with exogenous minerals. The highest surface tension reduction rate (57.744%) was obtained at 2.18% glucose (w/v); 14.67% pineapple peel (v/v); 2.38 g/L KH2PO4; and 0.15 g/L MgSO4.7H2O; whereas to obtain the maximum predicted value for EI24 (61.92%) the medium was composed by 2.24% glucose (w/v); 12.63% pineapple peel (v/v); 2.53 g/L KH2PO4; and 0.29 g/L MgSO4.7H2O.


Subject(s)
Ananas , Bacillus subtilis , Culture Media , Fruit
8.
Biotechnol Rep (Amst) ; 24: e00364, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31440459

ABSTRACT

The biosurfactant production is characterized by high costs with substrates, which does not make them sufficiently competitive against synthetic surfactants. The insertion of alternative sources of low cost, especially agro-industrial residue, is an excellent alternative to make this competitiveness viable. An alkaline pretreatment was used to extract the hemicellulose from corncob in order to enhance its C5 fraction, common to vegetable biomasses. The hemicellulosic corncob liquor was used with glucose and mineral salt solution as carbon and nutrients sources in a fermentation process for the growth of Bacillus subtilis. It was performed a 23 full factorial design to determine the best conditions for the surfactin production in relation to the following response variables: surface tension reduction rate (STRR) and emulsification index (EI24), from which were obtained two optimized bioproducts under specific conditions. The optimized biosurfactants found to be effected presenting a critical micelle concentration of 100 mg.L-1 and a maximum bioremediation potential of 85.18%, as well as maximum values of 57.38% and 65.30% for STRR and EI24 variables, respectively. Overall results pointed for a successful commercial application for the surfactin produced.

9.
Ágora (Rio J. Online) ; 22(1): 123-133, jan.-abr. 2019.
Article in Portuguese | LILACS, Index Psychology - journals | ID: biblio-986222

ABSTRACT

RESUMO: Esse trabalho é motivado pela homologia estabelecida, por Lacan, entre a mais-valia e o mais-de-gozar. Buscamos evidenciar o embasamento dessa homologia e apontar seus efeitos nos fundamentos da subjetividade capitalista. Para tanto, combinamos a leitura do Seminário 16, de Lacan, a uma abordagem de O capital, de Marx. Nesse processo, analisamos as articulações significantes do valor, do dinheiro e do fetiche na conformação da ordem simbólica do discurso capitalista.


Abstract: This paper is an examination of the homology between surplus-value and surplus-jouissance, as set out by Lacan. We seek to demonstrate the basis of this homology and point out its effects on capitalist subjectivity. To this end, we combine a reading of Lacan's Seminar XVI with Marx's Capital. Throughout this process, we analyze how the articulation of signifiers, such as value, money and fetish, configures the symbolic order of capitalist discourse.


Subject(s)
Capitalism , Fetishism, Psychiatric
10.
Lancet Infect Dis ; 16(10): 1154-1168, 2016 Oct.
Article in English | MEDLINE | ID: mdl-27373900

ABSTRACT

BACKGROUND: Although the risk of human papillomavirus (HPV) infection is greatest in young women, women older than 25 years remain at risk. We present data from the VIVIANE study of the HPV 16/18 AS04-adjuvanted vaccine in adult women after 7 years of follow-up. METHODS: In this phase 3, double-blind, randomised controlled trial, healthy women older than 25 years were enrolled (age stratified: 26-35 years, 36-45 years, and ≥46 years). Up to 15% in each age stratum had a history of HPV infection or disease. Women were randomly assigned (1:1) to receive HPV 16/18 vaccine or aluminium hydroxide control, with an internet-based system. The primary endpoint was vaccine efficacy against 6-month persistent infection or cervical intraepithelial neoplasia grade 1 or greater (CIN1+) associated with HPV 16/18. We did analyses in the according-to-protocol cohort for efficacy and total vaccinated cohort. Data for the combined primary endpoint in the according-to-protocol cohort for efficacy were considered significant when the lower limit of the 96·2% CI around the point estimate was greater than 30%. For all other endpoints and cohorts, data were considered significant when the lower limit of the 96·2% CI was greater than 0%. This study is registered with ClinicalTrials.gov, number NCT00294047. FINDINGS: The first participant was enrolled on Feb 16, 2006, and the last study visit took place on Jan 29, 2014. 4407 women were in the according-to-protocol cohort for efficacy (n=2209 vaccine, n=2198 control) and 5747 women in the total vaccinated cohort (n=2877 vaccine, n=2870 control). At month 84, in women seronegative for the corresponding HPV type in the according-to-protocol cohort for efficacy, vaccine efficacy against 6-month persistent infection or CIN1+ associated with HPV 16/18 was significant in all age groups combined (90·5%, 96·2% CI 78·6-96·5). Vaccine efficacy against HPV 16/18-related cytological abnormalities (atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesion) and CIN1+ was also significant. We also noted significant cross-protective efficacy against 6-month persistent infection with HPV 31 (65·8%, 96·2% CI 24·9-85·8) and HPV 45 (70·7%, 96·2% CI 34·2-88·4). In the total vaccinated cohort, vaccine efficacy against CIN1+ irrespective of HPV was significant (22·9%, 96·2% CI 4·8-37·7). Serious adverse events related to vaccination occurred in five (0·2%) of 2877 women in the vaccine group and eight (0·3%) of 2870 women in the control group. INTERPRETATION: In women older than 25 years, the HPV 16/18 vaccine continues to protect against infections, cytological abnormalities, and lesions associated with HPV 16/18 and CIN1+ irrespective of HPV type, and infection with non-vaccine types HPV 31 and HPV 45 over 7 years of follow-up. FUNDING: GlaxoSmithKline Biologicals SA.


Subject(s)
Adjuvants, Immunologic/administration & dosage , Human papillomavirus 16/immunology , Human papillomavirus 18/immunology , Papillomavirus Infections/prevention & control , Papillomavirus Vaccines/administration & dosage , Adult , DNA, Viral , Double-Blind Method , Female , Follow-Up Studies , Humans , Middle Aged , Papillomaviridae/immunology , Papillomaviridae/isolation & purification , Papillomavirus Vaccines/immunology , Papillomavirus Vaccines/therapeutic use , Uterine Cervical Neoplasms/prevention & control , Uterine Cervical Neoplasms/virology
11.
Bioprocess Biosyst Eng ; 38(4): 721-8, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25344826

ABSTRACT

A novel strategy for the production of lipase by Bacillus sp. ITP-001 in a stirred tank fermenter using perfluorodecalin (PFD) was studied. Firstly, a response surface methodology 2(2) with three central points was employed to optimise the effect of agitation speed and aeration rate in lipase production. According to the response from the experimental designs, 300 rpm (revolutions per minute) and 0.5 vvm (air volume/liquid volume per minute) were found to provide the best condition (lipolytic activity: LA = 3,140.76 U mL(-1)). Then, the influence of PFD concentration on the fermentation process was evaluated. Incorporation of PFD at all concentrations above 1% had no statistically significant influence on lipase production, that is, the previous optimisation allowed the reduction of the amount of PFD added besides increasing lipase production. Furthermore, PFD could be used in three sequential fermentations without altering the statistical production of lipase, reducing by 67% the cost of PFD addition.


Subject(s)
Bacillus/metabolism , Fluorocarbons/chemistry , Industrial Microbiology , Lipase/biosynthesis , Oxygen/chemistry , Biomass , Bioreactors , Fermentation , Hydrogen-Ion Concentration , Temperature
12.
Appl Biochem Biotechnol ; 168(2): 234-46, 2012 Sep.
Article in English | MEDLINE | ID: mdl-22736274

ABSTRACT

The aim of this work was to evaluate the activity of bromelain in pineapple plants (Ananas comosus var. Comosus), Pérola cultivar, produced in vitro in different culture conditions. This enzyme, besides its pharmacological effects, is also employed in food industries, such as breweries and meat processing. In this work, the enzymatic activity was evaluated in the tissues of leaves and stems of plants grown in culture medium without plant growth regulator. The most significant levels of bromelain were observed in leaf tissue after 4 months of culture in vitro in medium with a filter paper bridge, followed by medium gelled by the agar. The results of this study, regarding the different structures of the pineapple (leaves and stems) in vitro showed that the activity of bromelain varied depending on the culture conditions, the time and structure of which was quantified, ensuring a viable strategy in the production of seedlings with high levels of bromelain in subsequent phases of micropropagation.


Subject(s)
Ananas/enzymology , Ananas/growth & development , Bromelains/metabolism , Culture Techniques/methods , Enzyme Assays/methods , Ananas/metabolism , Bromelains/biosynthesis , Bromelains/isolation & purification , Culture Media/chemistry , Plant Leaves/enzymology , Plant Stems/enzymology , Proteolysis
13.
J Ind Microbiol Biotechnol ; 38(12): 1979-84, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21626207

ABSTRACT

Fungi producing high xylanase levels have attracted considerable attention because of their potential industrial applications. Batch cultivations of Aspergillus terricola fungus were evaluated in stirred tank and airlift bioreactors, by using wheat bran particles suspended in the cultivation medium as substrate for xylanase and ß-xylosidase production. In the stirred tank bioreactor, in physical conditions of 30°C, 300 rpm, and aeration of 1 vvm (1 l min⁻¹), with direct inoculation of fungal spores, 7,475 U l⁻¹ xylanase was obtained after 36 h of operation, remaining constant after 24 h. In the absence of air injection in the stirred tank reactor, limited xylanase production was observed (final concentration 740 U l⁻¹). When the fermentation process was realized in the airlift bioreactor, xylanase production was higher than that observed in the stirred tank bioreactor, being 9,265 U l⁻¹ at 0.07 vvm (0.4 l min⁻¹) and 12,845 U l⁻¹ at 0.17 vvm (1 l min⁻¹) aeration rate.


Subject(s)
Aspergillus/enzymology , Bioreactors/microbiology , Xylosidases/metabolism , Aspergillus/metabolism , Dietary Fiber , Fermentation
14.
BMC Womens Health ; 11: 18, 2011 May 25.
Article in English | MEDLINE | ID: mdl-21612599

ABSTRACT

BACKGROUND: Extensive information on cervical cancer is currently available. Its effectiveness in reducing anxiety in women receiving abnormal Pap tests is not clear. We investigated current practices of communicating abnormal Pap results to evaluate women's reactions and determine the sources of information they use subsequently. METHODS: A self-administered questionnaire-based study was performed in 1475 women in France, Spain and Portugal who had received an abnormal Pap smear result in the 12 months prior to completing the questionnaire. Questions covered methods of communication of the result, emotional reactions, support received (from the physician and entourage), and information sources, using pre-specified check box options and rating scales. Data were analyzed by country. RESULTS: Pap test results were mostly communicated by phone to Spanish women (76%), while physician letters were common in France (59%) and Portugal (36%). Frequent reactions were anxiety, panic and stress, which were less common in Spanish women than their French and Portuguese counterparts. After discussing with their physician, half of the participants were worried, despite rating highly the psychological support received. Over 90% of women in each country discussed their results with family or friends. Partners provided a high level of support. Overall, the abnormal diagnosis and consequences had a low to medium impact on daily, professional and family life and their relationships with their partner. Impact was higher in Spanish women than the French or Portuguese. Information on the diagnosis and its treatment was rated average, and nearly 80% of participants wanted more information, notably French women. Preferred sources were the physician and the Internet. CONCLUSIONS: Women expressed a strong wish for more information about cervical cancer and other HPV-related diseases, and that their physician play a major role in its provision and in support. There was a heavy reliance on the close entourage and the Internet for information, highlighting the need for dissemination of accurate material. Differences between countries suggest information management strategies may need to be tailored to different geographical regions.


Subject(s)
Cervix Uteri/pathology , Communication , Information Seeking Behavior , Papanicolaou Test , Social Support , Vaginal Smears/psychology , Adult , Anxiety , Female , France , Humans , Internet , Middle Aged , Panic , Physician-Patient Relations , Portugal , Retrospective Studies , Spain , Spouses/psychology , Stress, Psychological , Surveys and Questionnaires
15.
Braz. j. microbiol ; 38(1): 78-83, Jan.-Mar. 2007. tab
Article in English | LILACS | ID: lil-449371

ABSTRACT

Glucose-6-phosphate dehydrogenase (G6PDH) is an important enzyme used in biochemical and medical studies and in several analytical methods that have industrial and commercial application. This work evaluated the extraction of G6PDH in aqueous two-phase system (ATPS) of poly(ethyleneglycol) (PEG)/phosphate buffer, using as enzyme source a medium prepared through commercial baker's yeast disruption. Firstly, the effects of PEG molar mass on the enzyme partition and of homogenization and rest on the system equilibrium were investigated. Afterwards, several ATPS were prepared using statistical analysis (2² factorial design). The results, including kinetic and thermodynamic parameters for the G6PDH activity, showed partial purification of this enzyme in ATPS composed of 17.5 percent (w/w) PEG400 and 15.0 percent (w/w) phosphate. A high enzymatic recovery value (97.7 percent), a high partition coefficient (351), and an acceptable purification factor (2.28 times higher than in cell homogenate) were attained from the top phase. So, it was possible to attain an effective enzyme pre-purification by separating some contaminants with a simple method such as liquid-liquid extraction in aqueous two-phase systems (ATPS).


Glicose-6-fosfato desidrogenase (G6PDH) é uma importante enzima usada em estudos bioquímicos e médicos, bem como em diversos métodos analíticos com aplicação comercial e industrial. Neste trabalho foi avaliado a extração da G6PDH em sistemas de duas fases aquosas (ATPS) constituídos por poli(etilenoglicol) (PEG)/tampão fosfato, usando como fonte de enzima um meio preparado por rompimento de leveduras de panificação comercial. Inicialmente foram investigados os efeitos da massa molar do PEG na partição da enzima e da homogeneização e repouso no equilíbrio do sistema. Na sequência, diversos ATPS foram preparados usando análise estatística (planejamento fatorial 2²). Os resultados, incluindo parâmetros cinéticos e termodinâmicos para a atividade da G6PDH, indicaram parcial purificação desta enzima em ATPS constituídos por 17,5 por cento (p/p) PEG400 e 15,0 por cento (p/p) fosfato. Um alto valor de recuperação enzimática (97,7 por cento), um alto coeficiente de partição (351), e um fator de purificação aceitável (2,28 vezes maior que em homogenato celular) foram obtidos na fase superior do sistema. Assim, foi possível alcançar uma pré-purificação eficaz da enzima separando alguns contaminadores aplicando um método simples tal como a extração líquido-líquido em sistemas bifásicos (ATPS).


Subject(s)
Clinical Enzyme Tests , Ethylene Glycol , Glucose-6-Phosphatase , In Vitro Techniques , Industrial Microbiology , Oxidoreductases/analysis , Saccharomyces cerevisiae , Culture Media , Methods , Sampling Studies
16.
Braz. j. microbiol ; 33(3): 196-201, July-Sept. 2002. tab, graf
Article in English | LILACS | ID: lil-349767

ABSTRACT

Glucose-6-phosphate dehydrogenase (G6PDH) and hexokinase (HK) are important enzymes used in biochemical and medical studies and in several analytical methods. Aqueous two-phase system (ATPS) formed by a polymer solution and an electrolyte solution provides a method for the separation and purification of enzymes with several advantages, including biocompatibility and easy scale up of the process. In this work, the effects of different pH values on the storage stability and partitioning behavior (K, partition coefficient) of the enzymes G6PDH and HK from baker's yeast extract were investigated in ATPS. The results, obtained from the 17.5 percent PEG 400 : 15.0 percent phosphate system, showed that when the pH was increased from 5.0 to 8.8, the K HK increased 26-fold and the K G6PDH 2.2-fold. In the 20.0 percent PEG 1500 : 17.5 percent phosphate system, the K HK and K G6PDH increased 13 and 1.2-fold, when the pH value was increased from 3.8 to 8.8, respectively. This leads to the conclusion that the partition coefficient for both enzymes is favored by high pH values. A statistical analysis of the results was conducted to confirm this conclusion


Subject(s)
Clinical Enzyme Tests , Glucose , Hexokinase , In Vitro Techniques , Oxidoreductases , Yeasts , Fermentation , Methods
17.
Appl Biochem Biotechnol ; 98-100: 205-13, 2002.
Article in English | MEDLINE | ID: mdl-12018248

ABSTRACT

In a 5-L fermentor (NBS-MF 105), Saccharomyces cerevisiae (0.7 g/L) was inoculated into a liquid medium (pH 4.0) containing 17 g/L of glucose, 2.55 g/L of yeast extract, 4.25 g/L of peptone, 2.04 g/L of Na2HPO4 x 12H2O, 4.34 g/L of (NH4)2SO4 and 0.064 g/L of MgSO4 x 7H2O and aerobically cultivated at 35 degrees C for 22 h. Agitation and aeration were adjusted to attain initial kLa values of 15, 60, 135, and 230 h(-1). The glucose 6-phosphate dehydrogenase (G6PDH) productivity (PrG6PDH) obtained for kLa values of 15, 60, 135, and 230 h(-1) was 10.6, 31.8, 30.3, and 23.3 U/([Lx h]), respectively, whereas the cell productivity (Pr(x)) for the same kLa values were 0.24, 0.69, 0.69, and 0.49 g/[L x h], respectively. Thus, both events are coupled and depend on the dissolved oxygen in the medium.


Subject(s)
Glucosephosphate Dehydrogenase/metabolism , Saccharomyces cerevisiae/enzymology , Saccharomyces cerevisiae/growth & development , Fermentation , Kinetics , Models, Theoretical
18.
Appl Biochem Biotechnol ; 98-100: 265-72, 2002.
Article in English | MEDLINE | ID: mdl-12018254

ABSTRACT

Hexokinase (HK) and glucose 6-phosphate dehydrogenase (G6PDH) are important enzymes used in biochemical studies and in analytical methods. The stability of the enzymes can be affected by several variables, pH being one of them. The effect of pH on the stability of HK and G6PDH was evaluated in this work. Baker's yeast cells were suspended in 50 mM Tris-HCl buffer (pH 7.5) containing 5.0 mM MgCl2, and submitted to disruption by agitation with glass beads and in the presence of protease inhibitors. The cell-free extract was obtained by centrifugation (2880g; 10 min), followed by dilution into the buffers: 0.1 M acetate-acetic acid (pH: 4.0, 4.5, 5.0, or 5.5), 0.1 M phosphate buffer (pH: 6.0, 6.5, or 7.0), and 0.1 M Tris-HCl buffer (pH: 7.5, 8.0, 8.5, 9.0 or 9.5). The residual activity of HK and G6PDH, expressed as micromol of NADPH formed per min, were measured through a period of buffer-enzyme contact from 0 to 51 h at 4 degrees C. It was observed that up to 4 h both enzymes were stable in all buffers used. However, after 51 h HK was stable at pH 6.0 and 7.5, whereas G6PDH was stable at pH 7.0, 9.5, and between 4.5 and 5.5.


Subject(s)
Glucosephosphate Dehydrogenase/chemistry , Hexokinase/chemistry , Hydrogen-Ion Concentration , Enzyme Stability , Glucosephosphate Dehydrogenase/isolation & purification , Glucosephosphate Dehydrogenase/metabolism , Hexokinase/isolation & purification , Hexokinase/metabolism , Kinetics , Saccharomyces cerevisiae/enzymology , Time Factors
19.
RBCF, Rev. bras. ciênc. farm. (Impr.) ; 37(2): 177-187, maio-ago. 2001. tab, graf
Article in Portuguese | LILACS | ID: lil-314043

ABSTRACT

Foi estudada, neste trabalho, a purificação por extração líquido-líquido da enzima glicose-6-fosfato desidrogenase (G6PDH), de Saccharomyces cerevisiae, em sistemas de duas fases aquosas, preparados com polietilenoglicol (PEG) e sal citrato. Foram avaliados, também, a estabilidade e o equilíbrio do sistema, além do efeito da concentração de citrato de sódio, concentração e massa molar do PEG na partição desta enzima, com auxílio de um planejamento experimental do tipo fatorial 2ü. Os resultados das extrações mostraram que é possível purificar a G6PDH nesse tipo de sistema, com a condução do processo em duas etapas. A primeira delas, conduzida com 17 porcento (p/p) de PEG 400 e 20 porcento (p/p) de citrato...


Subject(s)
Enzyme Activation/physiology , Fructose , Glucosephosphate Dehydrogenase , In Vitro Techniques , Proteins/biosynthesis , Saccharomyces cerevisiae , Yeasts , Chromatography, Affinity , Chromatography, Ion Exchange/methods , Spectrophotometry
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