Priscilla Filomena Fonseca Amaral
Federal University of Rio de Janeiro
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Hotspot
Dive into the research topics where Priscilla Filomena Fonseca Amaral is active.
Publication
Featured researches published by Priscilla Filomena Fonseca Amaral.
Advances in Experimental Medicine and Biology | 2010
Priscilla Filomena Fonseca Amaral; Maria Alice Zarur Coelho; Isabel M. Marrucho; João A. P. Coutinho
Biosurfactants are surface-active compounds from biological sources, usually extracellular, produced by bacteria, yeast or fungi. Research on biological surfactant production has grown significantly due to the advantages they present over synthetic compounds such as biodegradability, low toxicity, diversity of applications and functionality under extreme conditions. Although the majority of microbial surfactants have been reported in bacteria, the pathogenic nature of some producers restricts the wide application of these compounds. A growing number of aspects related to the production of biosurfactants from yeasts have been the topic of research during the last decade. Given the industrial importance of yeasts and their potential to biosurfactant production, the goal of this chapter is to review the biosurfactants identified up to present, focusing the relevant parameters that influence biosurfactant production by yeasts and its characteristics, revealing the potential of application of such compounds in the industrial field and presenting some directions for the future development of this area, taking into account the production costs.
Yeast | 2006
Priscilla Filomena Fonseca Amaral; M. Lehocky; Ana Barros-Timmons; Maria Helena M. Rocha-Leão; Maria Alice Zarur Coelho; João A. P. Coutinho
In the present work, the surface characteristics of a wild‐type strain of Yarrowia lipolytica (IMUFRJ50682) were investigated. Six different methods to characterize cell surfaces—adhesion to polystyrene; hydrophobic interaction chromatography (HIC); microbial adhesion to solvents (MATS) test; zeta potential; microbial adhesion to hydrocarbons (MATH) test; and contact angle measurement (CAM)—were employed to explain the cell surface behaviour of Y. lipolytica (IMUFRJ50682). This Y. lipolytica strain presents significant differences at the cell surface compared with another Y. lipolytica strain (W29) previously reported in the literature. The main difference is related to the higher cell adhesion to non‐polar solvents. The proteins present on the cell wall of Y. lipolytica IMUFRJ50682 seem to play an important role in these particular surface characteristics because of the consistent reduction of this yeast hydrophobic character after the action of pronase on its cell wall. Copyright
BioMed Research International | 2010
Gizele Cardoso Fontes; Priscilla Filomena Fonseca Amaral; Marcio Nele; Maria Alice Zarur Coelho
In order to improve biosurfactant production by Yarrowia lipolytica IMUFRJ 50682, a factorial design was carried out. A 24 full factorial design was used to investigate the effects of nitrogen sources (urea, ammonium sulfate, yeast extract, and peptone) on maximum variation of surface tension (ΔST) and emulsification index (EI). The best results (67.7% of EI and 20.9 mN m−1 of ΔST) were obtained in a medium composed of 10 g 1−1 of ammonium sulfate and 0.5 g 1−1 of yeast extract. Then, the effects of carbon sources (glycerol, hexadecane, olive oil, and glucose) were evaluated. The most favorable medium for biosurfactant production was composed of both glucose (4% w/v) and glycerol (2% w/v), which provided an EI of 81.3% and a ΔST of 19.5 mN m−1. The experimental design optimization enhanced ΔEI by 110.7% and ΔST by 108.1% in relation to the standard process.
Química Nova | 2008
Gizele Cardoso Fontes; Priscilla Filomena Fonseca Amaral; Maria Alice Zarur Coelho
Biosurfactants are molecules extracellularly produced by bacteria, yeast and fungi that have significant interfacial activity properties. This review focuses on relevant parameters that influence biosurfactant production by yeasts. Many works have investigated the optimization of yeast biosurfactant production, mainly within the last decade, revealing that the potential of such microorganisms is not well explored in the industrial field. The main points to increase the process viability lays on the reduction of the production costs and enhancement of biosynthesis efficiency through optimization the culture conditions (carbon and nitrogen source, pH, aeration, speed agitation) and the selection of inexpensive medium components.
Brazilian Journal of Chemical Engineering | 2012
Gizele Cardoso Fontes; N. M. Ramos; Priscilla Filomena Fonseca Amaral; Márcio Nele; Maria Alice Zarur Coelho
In this work, the production of a biosurfactant synthesized by Yarrowia lipolytica using different renewable resources as carbon source was investigated. Crude glycerol, a biodiesel co-product, and clarified cashew apple juice (CCAJ), an agroindustrial residue, were applied as feedstocks for the microbial surfactant synthesis. The microorganism was able to grow and produce biosurfactant on CCAJ and crude glycerol, achieving maximum emulsification indexes of 68.0% and 70.2% and maximum variations in surface tension of 18.0 mN.m-1and 22.0 mN.m-1, respectively. Different organic solvents (acetone, ethyl acetate and chloroform - methanol) were tested for biosurfactant extraction. Maximum biosurfactant recovery was obtained with chloroform - methanol (1:1), reaching 6.9 g.L-1for experiments using CCAJ and 7.9 g.L-1for media containing crude glycerol as carbon source.The results herein obtained indicate that CCAJ and the co-product of biodiesel production are appropriate raw materials for biosurfactant production by Y. lipolytica.
Surface Engineering | 2008
Marián Lehocký; Priscilla Filomena Fonseca Amaral; Pavel Sťahel; Maria Alice Zarur Coelho; Ana Barros-Timmons; João A. P. Coutinho
Abstract The adhesion of Yarrowia lipolytic a to teflonlike thin films deposited by plasma on polycarbonate substrates was investigated through a series of tests in order to develop a substrate for strong and selective adhesion of Yarrowia lipolytica cells. Teflonlike thin films were prepared using atmospheric pressure surface barrier discharge with mixtures of octafluorocyclobutane (C4F8) and nitrogen as plasma gas. A variety of plasma gas feedrates and different deposition times were studied. The films were characterised by Fourier transform infrared and contact angle measurements using the sessile drop technique. Total surface energy and its components were calculated using the acid base theory. Attachment of the yeast cells was assessed by optical and scanning electron microscopy. The optimal deposition conditions for cell adhesion were determined using standard adhesion tests.
International Journal of Molecular Sciences | 2009
Priscilla Filomena Fonseca Amaral; Daniela Garcia; Miguel Cardoso; Marisa Mendes; Maria Alice Zarur Coelho; Fernando L.P. Pessoa
The use of enzymes in supercritical CO2 (SCCO2) has received extensive attention in recent years. Biocatalysts have the advantage of substrate specificity and SCCO2 offers several advantages over liquid solvents. This work deals with the utilization of SCCO2 as a medium for the enzymatic removal of phenol from aqueous solutions using tyrosinase. Since the presence of oxygen is crucial for the enzyme-catalyzed oxidation, the substantial solvating power of SCCO2 makes it a promising medium for such reactions. The conversion of phenol was higher at 10 MPa. Under near critical conditions (7 MPa, 35 °C), the addition of air at 5 × 105 Pa of pressure improved phenol removal.
International Journal of Environmental Studies | 2013
Luana Vieira da Silva; Ana P.M. Tavares; Etel Kameda; Eugénia A. Macedo; M. A. Z. Coelho; Priscilla Filomena Fonseca Amaral
Tyrosinase obtained from Agaricus bisporus was used to catalyze the decolourization of two reactive dyes: reactive yellow 15 (RY15) and reactive blue 114 (RB114). A 33 factorial design was used to evaluate the effects of enzyme concentration, pH of the reaction medium and temperature on the decolourization yield. From fitted mathematical models, response surfaces were determined and the best decolourization conditions obtained were 25 °C, enzyme concentration of 200 U/L and pH 7.0. At these conditions, a maximum decolourization of 36 and 20% for RY15 and RB114, respectively, was obtained. In order to improve decolourization, aeration of the media, enzyme type (crude or lyophilized) and additives (CaCl2 or CaCO3) were evaluated. The lyophilized enzyme without any protective compound presented a better performance. The aeration was a very important factor confirming that oxygen was limiting the reaction. The aeration of the medium with lyophilized tyrosinase improves the dye decolourization to more than 90%.
Polimeros-ciencia E Tecnologia | 2018
jonas de jesus gomes da costa neto; Roseli da Silva; Priscilla Filomena Fonseca Amaral; Maria Helena Rocha Leão; Taísa Gomes; Gizele Sant’Ana
The purpose of this study was to characterize, isolate and chemically modify tiger nut (Cyperus sculentus L.) starch with octenyl succinic anhydride. The efficiency of the chemical modification was 0.04. Chemical composition, particle morphology (SEM), particle size, X-ray diffraction, infrared analysis, thermogravimetric analysis, differential scanning calorimetry and swelling and solubility power were determined for characterization of the native and modified starch. Both showed similar chemical composition and amylose and amylopectin contents, as well as absorption spectra in the infrared region without modification of the molecular structure and A-type crystalline pattern. The particles of both had an oval and spherical shape. The modified starch was more resistant to temperature and the gelatinization process occurred at 67.52 °C. These results suggest that tiger nut starch has a great industrial potential.
Bioprocess and Biosystems Engineering | 2018
Luana Vieira da Silva; Maria Alice Zarur Coelho; Priscilla Filomena Fonseca Amaral; Patrick Fickers
Polyethylene glycol (PEG) is polymer that was used to replace NaCl (reference media) as an osmotic stress agent for the synthesis of erythritol by the osmophilic yeast Yarrowia lipolytica. Two strains, the wild-type strain IMUFRJ 50682 and the lab strain W29, were grown in the presence of PEG of different molecular weights. For strain IMUFRJ 50682, the erythritol titer was increased by 40% in the presence of PEG2000 as compared to the reference media (with NaCl). A similar increase was also observed for strain W29, except that it occurred in the presence of PEG6000. Moreover, in those experimental conditions neither strain produced mannitol, in contrast to the control medium. These results highlight that PEG could be used to increase erythritol productivity and to simultaneously inhibit mannitol synthesis, representing a good substitute for NaCl as an osmotic stress agent.