Marilia Penteado Stephan - Academia.edu (original) (raw)

Papers by Marilia Penteado Stephan

Ciencia Rural, Jan 29, 2010

Perfil eletroforético de lombo suíno adicionado de proteínas não cárneas SDS-PAGE electrophoretic... more Perfil eletroforético de lombo suíno adicionado de proteínas não cárneas SDS-PAGE electrophoretic pattern of pork loin enhanced with non-meat proteins RESUMO A legislação brasileira permite a adição intencional de proteínas não cárneas em alguns produtos cárneos; entretanto, há poucas técnicas adaptadas e próprias para controle desses ingredientes. Na presente pesquisa, empregou-se a técnica de eletroforese em gel de poliacrilamida na presença de dodecil-sulfato de sódio (SDS-PAGE) para comparar amostras de carne suína (lombo), adicionadas de 1,5% de proteínas não cárneas (proteína isolada de soja e concentrado protéico de soro de leite). Mediante a padronização de dois protocolos distintos de extração (uréia 6M e Tris-HCl-SDS-mercaptoetanol) e a utilização de controles positivos e negativos, obtiveram-se perfis eletroforéticos típicos do músculo e das proteínas utilizadas. Ambas as extrações utilizadas foram adequadas para separação das proteínas do soro de leite das proteínas da carne, mas a visualização dos marcadores da soja não foi possível em razão da sobreposição de bandas.

DOAJ (DOAJ: Directory of Open Access Journals), Feb 1, 2010

Birkhäuser Basel eBooks, 1983

Food Control, Nov 1, 2014

This study was carried out to assess physicochemical (color, moisture, protein and fat content) a... more This study was carried out to assess physicochemical (color, moisture, protein and fat content) and rheological properties (fracture stress, fracture strain, degree of solidity and stress decay), as well as to assess the authenticity (using SDS-PAGE) of Minas Frescal cheese in 21 commercial samples acquired in Southern Brazil. Large differences among the samples, which tended to present a yellowish white color were observed. Moisture and protein influenced on the rheological properties and cheeses showed a tendency to being viscous and firm. SDS-PAGE revealed a wide unexpected variability in their proteins profiles and a densitometric casein/b-lactoglobulin ratio allowed to distinguish authentic cheese from adulterated ones. The profiles suggest the irregular presence of whey in the composition of these products, contrary to the enzymatic process legally required. These results emphasize the need for a more effective control, mainly in the selection of raw material, aiming to offer consumers authentic products.

Azospirillum species participate in all steps of the nitrogen cycle except nitrification. They ca... more Azospirillum species participate in all steps of the nitrogen cycle except nitrification. They can fix molecular nitrogen and perform assimilatory nitrate reduction and nitrate respiration. Recent experiments showed that Azospirillum brasilense Sp. 7 grows under anaerobic conditions utilizing nitrate (Bothe et al. 1981), nitrite (Stephan et al. 1983) and nitrous oxide (Stephan et al. 1983) as respiratory electron acceptor. Under anaerobic conditions, nitrate respiration can also supply the energy for nitrogen fixation without supporting growth (Bothe et al. 1981). Nitrate-dependent nitrogenase activity lasts only 3–4 h until the enzymes of assimilatory nitrate reduction are formed (Bothe et al. 1981; 1983). An association between wheat plants and Azospirillum brasilense Sp. 7 has recently been investigated for N2-fixation (C2H2-reduction and denitrification (N2O-formation) activity. 25 germinated wheat seeds and an Azospirillum culture with about 1.3 × 109 cells were inoculated onto the surface of a semisolid agar/mineral salt medium in i 1 flasks and incubated for a week in a growth chamber under light/dark cycles (12.5 h at 33o C in the light and 11.5 h at 23o C in the dark). C2H2-reduction and N2O-formation activities were then assayed for a day where the gas phase consisted of argon supplemented with 0.5% C2 H2 and 1–2% O2.

Fems Microbiology Letters, 1991

Biochemical Society Transactions, Apr 1, 1981

Heliyon, Jul 1, 2020

The Artisan Minas Cheese (AMC) is the oldest and most traditional Brazilian cheese, it is produce... more The Artisan Minas Cheese (AMC) is the oldest and most traditional Brazilian cheese, it is produced in several regions of the state of Minas Gerais, such as the Serro region. The most striking features of the AMC-Serro are the use of raw milk and natural bacteria from the whey, popularly known as pingo, as well as the use of the rind washing process. The aim of the present study was to evaluate the proteolysis of the AMC-Serro from three different producers, during 60 days of maturation, and to relate the proteolysis to the producing farms, the production season and the rind washing during ripening. For this purpose, TRICINE-SDS-PAGE, proteolysis extension and depth indices, moisture, and texture (firmness) were evaluated. It was concluded that the temperature and moisture of the cheeses, that were determined by the location of the ripening room, the production season and the rind washing, were the most important factors. The degree of proteolysis also had an impact on the water loss during ripening, with effect on cheese safety. The results obtained in this study may be used to better understand the transformations during ripening of AMC-Serro and help the small traditional farmers to improve their product's quality and stability.

Archives of Microbiology, Jul 1, 1984

Denitrification ability is sporadically distributed among diverse bacteria, archaea, and fungi. I... more Denitrification ability is sporadically distributed among diverse bacteria, archaea, and fungi. In addition, disagreement has been found between denitrification gene phylogenies and the 16S rRNA gene phylogeny. These facts have suggested potential occurrences of horizontal gene transfer (HGT) for the denitrification genes. However, evidence of HGT has not been clearly presented thus far. In this study, we identified the sequences and the localization of the nitrite reductase genes in the genomes of 41 denitrifying Azospirillum sp. strains and searched for mobile genetic elements that contain denitrification genes. All Azospirillum sp. strains examined in this study possessed multiple replicons (4 to 11 replicons), with their sizes ranging from 7 to 1,031 kbp. Among those, the nitrite reductase gene nirK was located on large replicons (549 to 941 kbp). Genome sequencing showed that Azospirillum strains that had similar nirK sequences also shared similar nir-nor gene arrangements, especially between the TSH58, Sp7 T , and Sp245 strains. In addition to the high similarity between nir-nor gene clusters among the three Azospirillum strains, a composite transposon structure was identified in the genome of strain TSH58, which contains the nir-nor gene cluster and the novel IS6 family insertion sequences (ISAz581 and ISAz582). The nirK gene within the composite transposon system was actively transcribed under denitrification-inducing conditions. Although not experimentally verified in this study, the composite transposon system containing the nir-nor gene cluster could be transferred to other cells if it is moved to a prophage region and the phage becomes activated and released outside the cells. Taken together, strain TSH58 most likely acquired its denitrification ability by HGT from closely related Azospirillum sp. denitrifiers. IMPORTANCE The evolutionary history of denitrification is complex. While the occurrence of horizontal gene transfer has been suggested for denitrification genes, most studies report circumstantial evidences, such as disagreement between denitrification gene phylogenies and the 16S rRNA gene phylogeny. Based on the comparative genome analyses of Azospirillum sp. denitrifiers, we identified denitrification genes, including nirK and norCBQD, located on a mobile genetic element in the genome of Azospirillum sp. strain TSH58. The nirK was actively transcribed under denitrification-inducing conditions. Since this gene was the sole nitrite reductase gene in strain TSH58, this strain most likely benefitted by acquiring denitrification genes via horizontal gene transfer. This finding will significantly advance our scientific knowledge regarding the ecology and evolution of denitrification.

Journal of Agricultural Science and Technology: B, Jun 28, 2019

Anais do Congresso Brasileiro de Engenharia Química, Sep 26, 2014

Plant Foods for Human Nutrition

Brazilian Journal of Food Technology, 2019

Resumo O objetivo do trabalho foi avaliar as atividades antioxidante e antimicrobiana de hidrolis... more Resumo O objetivo do trabalho foi avaliar as atividades antioxidante e antimicrobiana de hidrolisados proteicos de soro de leite obtidos por diferentes proteases (Alcalase e Flavourzyme) e sua mistura (proporção 50:50). Previamente à hidrólise enzimática, o soro de leite foi concentrado por ultrafiltração com membranas cerâmicas tubulares. A reação enzimática foi realizada de acordo com o método pH-stat, sendo coletadas alíquotas com diferentes graus de hidrólise ( GH), ao longo de cada hidrólise proteica. Os hidrolisados foram analisados quanto a estimativa do teor de peptídeos, atividade antioxidante pelos métodos de captura do radical livre ABTS+ e do radical peroxila (Oxygen radical antioxidant capacity - ORAC), eletroforese e atividade antimicrobiana. Os máximos GH alcançados foram 15%, 52% e 63%, para Flavourzyme, mistura das enzimas e Alcalase, respectivamente. A atividade antioxidante aumentou com o GH. Os hidrolisados proteicos obtidos pela Alcalase apresentaram maiores ati...

Carbohydrate Research, 1997

Acetobacter diazotrophicus is an acid-tolerant nitrogen-fixing bacterium found in roots, rhizosph... more Acetobacter diazotrophicus is an acid-tolerant nitrogen-fixing bacterium found in roots, rhizosphere, stems, and leaves of sugar cane (Saccharum officinarum) cultivated in Brazil. The O-polysaccharide from the lipopolysaccharide of the root isolate strain PAL 5 has been determined by a combination of methylation analysis and two-dimensional high field NMR spectroscopy. The pentasaccharide repeat has the structure: [formula: see text] Minor resonances in the NMR spectra are consistent with the presence of a proportion of repeating units which lack the beta-D-Glc side-chain.

Capítulo 3: Síndrome Metabólica: Uma associação entre hábitos de vida não saudáveis e fatores de ... more Capítulo 3: Síndrome Metabólica: Uma associação entre hábitos de vida não saudáveis e fatores de risco cardiovasculares em estudantes universitários ..

The objective of this work was to evaluate the antioxidant and antimicrobial activities of whey p... more The objective of this work was to evaluate the antioxidant and antimicrobial activities of whey protein hydrolysates obtained using different commercial proteases (Alcalase and Flavourzyme) as well as their blend (50:50 ratio). Prior to the enzymatic hydrolysis, the whey was concentrated by ultrafiltration using tubular ceramic membranes. The enzymatic reaction was carried out according to the pH-stat method, in which aliquots were collected with different degrees of hydrolysis (DH) during the protein hydrolysis. The protein hydrolysates were evaluated with respect to the estimated peptides content, antioxidant activity by capture of free radical ABTS+ and the peroxyl radical (Oxygen radical antioxidant capacity - ORAC) methods, electrophoresis and antimicrobial activity. The maximum DH values reached were: 15%, 52% and 63% for Flavourzyme, the blend of enzymes and Alcalase, respectively. The antioxidant activity increased with the DH. The protein hydrolysates obtained using Alcalas...

Archives of Microbiology, Oct 1, 1981

... Can J Microbiol 24:1395 - 1403 Neyra CA, van Berkum P (1977) Nitrate reduction and nitrogenas... more ... Can J Microbiol 24:1395 - 1403 Neyra CA, van Berkum P (1977) Nitrate reduction and nitrogenaseactivity in Spirillum lipoferum. Can J Microbiol 23:306-310 Neyra CA, D6bereiner J, Lalande R, Knowles R (1977) Denitrification by Nz-fixing Spirillum lipoferum. ...