Gizele Cardoso Fontes

Factorial Design to Optimize Biosurfactant Production by Yarrowia lipolytica

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.

Produção de biossurfactante por levedura

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.

Renewable resources for biosurfactant production by yarrowia lipolytica

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.

Characterization of Antibiotic-Loaded Alginate-Osa Starch Microbeads Produced by Ionotropic Pregelation

The aim of this study was to characterize the penicillin-loaded microbeads composed of alginate and octenyl succinic anhydride (OSA) starch prepared by ionotropic pregelation with calcium chloride and to evaluate their in vitro drug delivery profile. The beads were characterized by size, scanning electron microscopy (SEM), zeta potential, swelling behavior, and degree of erosion. Also, the possible interaction between penicillin and biopolymers was investigated by differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analysis. The SEM micrograph results indicated a homogeneous drug distribution in the matrix. Also, based on thermal analyses (TGA/DSC), interactions were detected between microbead components. Although FTIR spectra of penicillin-loaded microbeads did not reveal the formation of new chemical entities, they confirmed the chemical drug stability. XRD patterns showed that the incorporated crystalline structure of penicillin did not significantly alter the primarily amorphous polymeric network. In addition, the results confirmed a prolonged penicillin delivery system profile. These results imply that alginate and OSA starch beads can be used as a suitable controlled-release carrier for penicillin.

Produção do “leite” de junça (cyperus esculentus) via planejamento de experimentos

RESUMO: A junça, tiger nuts ou chufa é um tubérculo pertencente a família das Cyperáceas. Desse tubérculo se extrai um extrato chamado de “leite” de junça no Brasil ou “Horchata de chufa” na Espanha, bebida não alcoólica com grande comercialização, principalmente, na região de Valência (40 a 50 milhões de litros), que ainda carece de uma produção em escala industrial que considere, principalmente, melhores condições nutricionais. Portanto, o objetivo foi avaliar a extração do leite de junça por meio de uma investigação exploratória quanto às condições experimentais estatisticamente significativas para as variáveis respostas rendimento e teor de proteína. Para avaliação das condições experimentais, foi realizado um planejamento fracionário para definir as variáveis independentes significantes (tempo de saturação, temperatura de saturação, concentração de metabisulfito de sódio e tempo de moagem). Os resultados indicaram que apenas os fatores concentração de metabisulfito e sua interação com o tempo de saturação foram marginalmente significativos para a variável resposta rendimento. Para a proteína não houve fatores e interações significativos (p<0,05)