Valeria Reginatto | Universidade de São Paulo (original) (raw)

Papers by Valeria Reginatto

Revista do Instituto Adolfo Lutz

O polvilho azedo é um amido de mandioca em que são feitas modificações químicas e enzimáticas, se... more O polvilho azedo é um amido de mandioca em que são feitas modificações químicas e enzimáticas, sendo usado na fabricação de produtos tradicionais, como pão de queijo, em função de sua propriedade de expansão, que induz a formação de estrutura leve e alveolar, mesmo sem adição de qualquer produto químico ou fermento biológico. O presente trabalho foi realizado com o objetivo de estabelecer alguns procedimentos técnicos simples para efetuar a avaliação prévia da propriedade de expansão do polvilho azedo a ser utilizado. Foi estudada a relação entre os amidos de mandioca nativos e os do polvilho azedo produzido em laboratório. Um questionário foi aplicado entre os padeiros locais com o objetivo de averiguar o motivo para efetuar a escolha do polvilho azedo, o que conduziu a algumas marcas; essas marcas selecionadas foram também analisadas neste estudo. As características referentes a fator ácido, pH, volume específico, poder de inchamento e viscosidade intrínseca apresentaram boa corre...

Acta Scientiarum-technology, Feb 26, 2014

Methods for the enrichment of an anaerobic sludge with H 2-producing bacteria have been compared ... more Methods for the enrichment of an anaerobic sludge with H 2-producing bacteria have been compared by using cassava processing wastewater as substrate. The sludge was submitted to three different pretreatments: 1) heat pretreatment by boiling at 98°C for 15 min., 2) heat pretreatment followed by sludge washout in a Continuous Stirring Tank Reactor (CSTR) operated at a dilution rate (D) of 0.021 h-1 , and 3) sludge washout as the sole enrichment method. The pretreated sludge and the sludge without pretreatment (control) were employed in the seeding of 4 batch bioreactors, in order to verify the volume and composition of the generated biogas. Maximum H 2 production rates (R m) from the pretreated sludges were estimated by the modified Gompertz model. Compared to the control, H 2 production was ca. 4 times higher for the sludge submitted to the heat pretreatment only and for the sludge subjected to heat pretreatment combined with washout, and 10 times higher for washout. These findings demonstrated that the use of sludge washout as the sole sludge pretreatment method was the most effective in terms of H 2 production, as compared to the heat and to the combined heat and washout pretreatments.

RESUMO-Neste trabalho foi estudado o efeito de diferentes pré-tratamentos sobre uma cultura mista... more RESUMO-Neste trabalho foi estudado o efeito de diferentes pré-tratamentos sobre uma cultura mista coletada de um sistema anaeróbio de tratamento de vinhaça com relação à produção de H 2. Foram realizados os seguintes pré-tratamentos: 1) Tratamento térmico a 100°C por 15 min.; 2) Tratamento térmico a 100°C por 60 min; 3) Tratamento térmico a 80°C por 15 min; 4) Tratamento térmico a 80°C por 60 min; 5) Tratamento ácido (pH 3 com HCl); 6) Tratamento combinado (pH 3 e fervura por 30 min.); 7 e 8) Lavagem seletiva do lodo em reator contínuo, operado a 50°C com TRH de 12 h e 6 h. O modelo cinético de Gompertz modificado foi utilizado para a obtenção dos parâmetros cinéticos. As maiores velocidades de produção (Rm) foram observadas com o lodo que sofreu pré-tratamento térmico 80°C por 15 min.; térmico 80°C por 60 min. e ácido pH 3 por 24h; 12,2; 15,6 e 16,5 mL/h, respectivamente. Em ensaios de longa duração (por 36 dias), o tratamento ácido demonstrou ser o mais efetivo para o enriquecimento da cultura mista para a produção de H 2. 1-INTRODUÇÃO Um dos maiores desafios para a produção biológica de H 2 é a preparação de grandes quantidades de fontes naturais de inóculo estáveis e ativos. Para aumentar a velocidade de produção de H 2 é importante desenvolver métodos que inibam a atividade das bactérias consumidoras de H 2 , tais como as metanogênicas, desnitrificantes e redutoras de sulfato, e que favoreçam o enriquecimento das bactérias produtoras de H 2 , tais como as dos gêneros Clostridium e Enterobacter (Hawkes et al., 2002).

Elsevier eBooks, 2018

Abstract The growing demand for sustainable energy associated with the need for alternative waste... more Abstract The growing demand for sustainable energy associated with the need for alternative wastewater treatment has led to the development of several efficient and sustainable systems for energy conversion. The microbial fuel cell and the microbial electrolysis cell have gained scientific and technological importance in recent years because they fit quite well in the current global scenario. The main advantage of microbial fuel cells is their ability to treat an effluent and to generate electric power simultaneously. The main goal of microbial electrolysis cells is to produce hydrogen sustainably through consumption of a residue. In this chapter, we address the fundamentals of biological fermentation and wastewater treatment as well as the use of microbial fuel cells and microbial electrolysis cells to treat wastewater and to cogenerate electricity and hydrogen.

Frontiers in Sustainable Food Systems

Ever-increasing biofuel production has raised the supply of glycerol, an abundant waste from etha... more Ever-increasing biofuel production has raised the supply of glycerol, an abundant waste from ethanolic fermentation and transesterification, for biodiesel production. Glycerol can be a starting material for sustainable production of 1,3-propanediol (1,3 PD), a valued polymer subunit. Here, we compare how Clostridium pasteurianum DSMZ 525, a well-known 1,3-PD-producer, and the non-solventogenic Clostridium beijerinckii Br21 perform during glycerol fermentation. Fermentative assays in 80-, 390-, or 1,100-mM glycerol revealed higher 1,3-PD productivity by DSMZ 525 compared to Br21. The highest 1,3-PD productivities by DSMZ 525 and Br21 were obtained in 390 mM glycerol: 3.01 and 1.70 mM h−1, respectively. Glycerol uptake by the microorganisms differed significantly: C. beijerinckii Br21 consumed 41.1, 22.3, and 16.3%, while C. pasteurianum consumed 93, 44.5, and 14% of the initial glycerol concentration in 80, 390, and 1,100 mM glycerol, respectively. In 1,100 mM glycerol, C. beijerinck...

Brazilian Journal of Chemical Engineering

Microbial fuel cells are an eco-friendly technology that decontaminate wastewater and generate el... more Microbial fuel cells are an eco-friendly technology that decontaminate wastewater and generate electricity by the action of exoelectrogenic microbes. However, mechanisms such as bioanode formation and stabilization and the electron transfer mechanism still have to be elucidated and enhanced before this technology can be scaled up for practical applications. Electrochemical characterization showed that a more electroactive biofilm (power density of 77 ± 8 mW m−2) emerged under a charged surface provided by a continuously applied electric current. Among the different molecules evaluated as electron transfer mediator, methylene green was the only molecule that improved cell performance. Methylene green addition increased the cell voltage by 20% and maintained the cell stable for six more days as compared to the control. Bioanode microbial community analysis revealed a high abundance of Arcobacter and Dechloromonas, which may play roles in electricity generation and methylene green discoloration. Microbial fuel cell voltage and stability were increased upon addition of methylene green, which was degraded in the bioanode over time. Identification of microbial members helps to understand MFC performance and to elucidate how methylene green improves MFC stability.

Bioelectrochemical Systems, 2020

Sour cassava starch (polvilho azedo ) is a chemically and enzymatically modified starch. It is us... more Sour cassava starch (polvilho azedo ) is a chemically and enzymatically modified starch. It is used to prepare the traditional baked goods. Because of its satisfactory expansion property, a light and alveolar structure is produced in baked food prepared with sour cassava starch, without adding any chemical or biological ferment. This study reports some easy and simple procedures for pre-estimating sour cassava starch expansion property. The correlation between the native cassava starches and the laboratory-produced sour cassava starch was analyzed. An investigation among the local bakers was carried out for inquiring into the polvilho azedo choice, and it disclosed some product brands. The polvilho azedo samples from these brands were also evaluated. Acid factor, pH, specific volume, swelling power and intrinsic viscosity characteristics were directly correlated with expansion property. The procedures for determining acid factor, pH and weight loss are easy and accessible methodolog...

Bioresource Technology, 2019

This research work has succeeded in recovering energy from glucose by generating H2 with the aid ... more This research work has succeeded in recovering energy from glucose by generating H2 with the aid of a Clostridium beijerinckii strain and obtaining electrical energy from compounds present in the H2 fermentation effluent in a microbial fuel cell (MFC) seeded with native port drainage sediment. In the fermentation step, 49.5% of the initial glucose concentration (56 mmol/L) was used to produce 104 mmol/L H2; 5, 33, 3, and 1 mmol/L acetate, butyrate, lactate, and ethanol also emerged, respectively. MFC tests by feeding the anodic compartment with acetate, butyrate, lactate (individually or as a mixture), or the H2 fermentation effluent provided power density values ranging between 0.6 and 1.2 W/m 2. Acetate furnished the highest power density with a nanowire-rich biofilm despite the lowest anode bacterial concentration (10 12 16S gene copies/g of sediment). Nonconventional exoelectrogenic microbial communities were observed in the acetate-fed MFC; e.g., Pseudomonadaceae (Pseudomonas) and Clostridia (Acidaminobacter, Fusibacter).

Nature Microbiology, 2019

In the version of this Article originally published, the name of the author 'Mathew Robert Brown'... more In the version of this Article originally published, the name of the author 'Mathew Robert Brown' was incorrectly written as 'Mathew Brown' in the main author list and as 'Matthew Brown' in the Global Water Microbiome Consortium list. In addition, in the Global Water Microbiome Consortium list, the names of the authors 'Kevin F. Boehnke' , 'Janeth Sanabria' and ' Adalberto Noyola' were incorrectly written as 'Kevin Boehnke' , 'Janeth Sanabria Gómez' and ' Adalberto Noyola Robles' , respectively. The names have now been corrected and the author initials in the author contributions section updated accordingly.

Journal of Material Cycles and Waste Management, 2017

Fermentation can use renewable raw materials as substrate, which makes it a sustainable method to... more Fermentation can use renewable raw materials as substrate, which makes it a sustainable method to obtain H 2. This study evaluates H 2 production by a mixed culture from substrates such as glucose and derivatives from sugarcane processing (sucrose, molasses, and vinasse) combined with landfill leachate. The leachate alone was not a suitable substrate for biohydrogen production. However, leachate blended with glucose, sucrose, molasses, or vinasse increased the H 2 production rate by 2.0-, 2.8-, 4.6-, and 0.5-fold, respectively, as compared with the substrates without the leachate. Determination of metals (Cu, Cd, Pb, Hg, Ni, and Fe) at the beginning and at the end of the fermentative assays showed how they were consumed during the fermentation and demonstrated improved H 2 production. During fermentation, Cu, Fe, and Cd were the most consumed leachate metals. The best substrate combination to produce H 2 was molasses and leachate, which gave high volumetric productivity-469 ml H 2 /l h. However, addition of the leachate to the substrates stimulated lactic acid formation pathways, which lowered the H 2 yield. The use of leachate combined with sugarcane processing derivatives as substrates could add value to the leachate and reduce its polluting power, generating a clean energy source from renewable raw materials.

Renewable Energy, 2015

ABSTRACT Lignocellulosic materials are potential renewable substrates for fermentative H2 product... more ABSTRACT Lignocellulosic materials are potential renewable substrates for fermentative H2 production; however, most of the methods available to hydrolyze these materials produce fermentation inhibitors. This study assessed the effect of three different groups of inhibitors on fermentative H2 production by a mixed culture: (1) acetic acid; (2) furan derivatives, such as furfural and 5-hydroxymethylfurfural (HMF); and (3) phenolic monomers, such as vanillin, syringaldehyde, and 4-hydroxybenzoic acid (HBA). Conduction of batch assays in the presence of glucose and different concentrations of inhibitors helped to assess how the inhibitors affected the kinetic parameters of the modified Gompertz model (Rm, Hmax, and λ). The concentrations of inhibitors that reduced 50% of the maximum H2 production rate (IC50) were estimated. In terms of IC50, HBA provided the largest inhibition, 0.38 g L−1, which is a novel result in the literature. HBA was followed by HMF and furfural, 0.48 and 0.62 g L−1, respectively. Vanillin, syringaldehyde, and acetic acid at 0.71; 1.05; and 5.14 g L−1 provided the same inhibition level, respectively. Knowledge about the degree of inhibition of these compounds shall contribute to sustainable H2 production from lignocellulosic substrates.

Biocatalysis and Agricultural Biotechnology

Um total de 626 microrganismos foram isolados de amostras de solos e de material celulosico em de... more Um total de 626 microrganismos foram isolados de amostras de solos e de material celulosico em decomposicao, coletadas em varias regioes brasileiras. Destes, um fungo mesofilico, o qual foi identificado como Trichoderma longibrachiatum, foi selecionado e utilizado em estudos de producao e caracterizacao de enzimas que promovem a degradacao de materiais celulosicos. Celuloses comerciais e residuas agroindustriais compuseram as fontes de carbono. As maiores atividades de hidrolise de papel de filtro, celulose microcristalina e carboximetilcelulose, foram obtidas, apos crescimento do microrganismo em Solka-Floc, enquanto que β-glicosidase e xilanase apresentaram um maximo de atividade apos crescimento em meio liquido contendo bagaco de cana. A atividade do sistema celulolitico determinada por hidrolise de papel de filtro apresentou pH otimo na faixa de 4.6 e 5.0 e conservou 87%. de sua atividade depois de 24 horas de incubacao na faixa de pH 4.4 e 5.0. A temperatura otima de acao o foi...

Journal of Environmental Chemical Engineering

Industrial Crops and Products