Tatiana Felix Ferreira

Factors Influencing Crude Oil Biodegradation by Yarrowia lipolytica

Yarrowia lipolytica is unique strictly aerobic yeast with the ability to efficiently degrade hydrophobic substrates such as n-alkenes, fatty acids, glycerol and oils. In the present work, a 24 full factorial design was used to investigate the influence of the independent variables of temperature, agitation, initial cell concentration and initial petroleum concentration on crude oil biodegradation. The results showed that all variables studied had significant effects on the biodegradation process. Temperature, agitation speed and initial cell concentration had positive effects, and initial petroleum concentration had a negative effect. Among the crude oil removal conditions studied, the best temperature and agitation conditions were 28oC and 250 rpm, respectively.

A New Strategy for Acetogenic Bacteriacell Growth and Metabolites Production Using Syngas in Lab Scale

Syngas fermentation by acetogenic bacteria present a major bottleneck, which is the low solubility of the substrates (CO and CO2) and, therefore, the low productivity caused by low cell density. In lab scale, many studies are conducted in serum bottles and agitated in incubation shakers with bottles kept vertically. In the present study, the serum bottles were kept horizontally in a new strategy to increase turbulence and, as a consequence, the mas transfer. Cell growth of Clostridium carboxidivorans (DSM 15243), Clostridium ragsdalei (DSM 15248) and Clostridium ljungdahlii (DSM 13528) was increased by the increase in the availability of CO and CO2 in the liquid medium. Cell growth of C.carboxidivoransincreased 3.7 times and the specific growth rate became 50% higher. Ethanol and acetic acid production were also favored by this strategy. C.carboxidivorans was thebest specie for ethanol production.

Optimización de la Concentración de L-Cisteína para la producción de 1,3-Propanodiol por una vía Biotecnológica

Resumen Se ha realizado la conversion de glicerol en 1,3-propanodiol (1,3-PDO) usando la cepa Citrobacter freundii ATCC 8090. El 1,3-PDO es una molecula bifuncional que puede ser utilizada para muchas aplicaciones, siendo asi de gran interes comercial. Una ruta mas reciente para la produccion de este compuesto es la via biotecnologica utilizando algunos microorganismos capaces de convertir anaerobicamente glicerol en 1,3-PDO. La conversion realizada hace necesaria la adicion de cisteina al medio de cultivo. Se realizaron cinco experimentos con cinco concentraciones de cisteina con el fin de verificar cual es la menor concentracion posible que no afecta la conversion de glicerol en 1,3-PDO. Las concentraciones utilizadas fueron 0,05; 0,10; 0,15; 0,20 y 0,25 g.L -1 . Los rendimientos fueron 15, 20, 26, 35 y 28 % respectivamente. De acuerdo a los resultados se concluye que la concentracion optima de cisteina para la produccion de 1,3-PDO es 0,20 g.L -1 . Palabras clave: 1,3-propanodiol, 1,3-PDO, Citrobacter freundii, cisteina, glicerol

A new method to obtain β-glucan from Saccharomyces cerevisiaecells

In this work, a simple method was developed to increase cell wall porosity and to achieve partial hydrolysis of β-glucan. First, the cells were permeabilized using ethanol under agitation. Then the cells were treated with glass beads to increase cell wall porosity and subjected to an enzymatic treatment to degrade glycogen at 65 °C for 30 minutes. Finally, the cells were incubated at 57 °C for 2 hours to partially degrade β-glucan. Whole cells, permeabilized cells and permeabilized cells with partially hydrolyzed β-glucan were evaluated by optical microscopy and transmission electron microscopy. From the images of permeabilized cells with partially hydrolyzed β-glucan it was possible to visualize structures named “ghosts”, which are alike along microcapsules containing β-glucan. These structures can be used to aggregate β-glucan in food industrialized products.