Janaína Fernandes de Medeiros Burkert

Biodegradation of phenol by a newly Aspergillus sp. strain isolated from a contaminated soil in southern Brazil

The main goal of this work was to study the biodegradation of phenol in batch mode by a filamentous fungus isolated from a contaminated site in Southern Brazil. A better performance was obtained by previous adaptation of the microorganism to the toxic chemical. A 23 experimental design was proposed and it could be observed total phenol degradation in 72 h using 500 mg L-1 glucose, inoculum of 20% and agitation of 200 rpm, resulting a biodegradation rate of 3.76 mg L-1 h-1. In relation to phenol tolerance, Aspergillus sp. LEBM2 was able to consume up to 989 ± 15 mg L-1.

Enzymatic synthesis optimization of isoamyl butyrate

Lipozyme TL IM was used to catalyse the esterification of isoamyl alcohol and butyric acid. A fractional factorial design was employed to evaluate the effects of temperature (30, 40, 50 °C), alcohol:acid molar ratio (1:1, 2:1, 3:1), enzyme concentration (0.003, 0.0115, 0.020 g mL-1), butyric acid concentration (0.1, 0.3, 0.5 mol L-1) and shaking rate (50, 115, 180 rpm) on the ester yield. With these results, the levels were redefined to a 23 factorial design. The maximum yield of ester was obtained at 30 oC, 180 rpm, alcohol:acid molar ratio of 1:1, enzyme concentration of 0.021 g mL-1 and butyric acid concentration of 0.5 mol L-1. Under the optimal conditions, 92% esterification was attained with an ester concentration of 0.9 mol L-1. Isoamyl alcohol from fusel oil was used under the same conditions and resulted in 93% esterification and an ester concentration of 1.0 mol L-1.

Simultaneous enzymatic hydrolysis and lactic fermentation to obtain a yogurt with low lactose content

In a single-stage process with the simultaneous addition of β-galactosidase and lactic culture, the lactose conversion, the processing time, viscosity and syneresis were evaluated. Fermentation was promoted by lactic culture containing two probiotic microorganisms, Bifidobacterium animalis and Lactobacillus acidophilus, associated with the typical microorganisms of yogurt. An enzymatic preparation containing β-galactosidases from Kluyveromyces lactis and Aspergillus niger was used. A central composite design (23 trials plus three central points) was proposed in order to evaluate the effects of initial lactose concentration, enzyme concentration and the time of addition of the enzyme. The following conditions were established: initial lactose concentration of 91 g L-1, enzyme concentration of 0.5 g L-1 and enzyme addition at the beginning of fermentation. In these conditions, a decrease in processing time (from 4.55 to 3.68 h) and an increase in lactose conversion (from 15.2 to 97.9%) were observed in relation to the fermentation without enzyme addition, and no detrimental changes in some physical properties of yogurt (viscosity, and syneresis).

Evaluation of the composition of culture medium for yeast biomass production using raw glycerol from biodiesel synthesis

The work herewith investigated the production of yeast biomass as a source of protein, using Yarrowia lipolytica NRRL YB-423 and raw glycerol from biodiesel synthesis as the main carbon source. A significant influence of glycerol concentration, initial pH and yeast extract concentration on biomass and protein content was observed according to the 2v5-1 fractional design. These factors were further evaluated using a central composite design and response surface methodology, and an empirical model for protein content was established and validated. The biomass of Yarrowia lipolytica NRRL YB-423 reached 19.5 ± 1.0 g/L in shaken flasks cultivation, with a protein content of 20.1 ± 0.6% (w/w).

Aceitação sensorial de bebidas lácteas potencialmente simbióticas

A procura por alimentos funcionais, como leites fermentados com culturas microbianas probioticas, aumentou o interesse em pesquisas para manter estes micro-organismos viaveis no produto. Neste sentido, o objetivo deste trabalho foi formular um leite fermentado sabor morango agregado de beneficios potencialmente prebioticos e probioticos, apresentando caracteristicas sensoriais adequadas. Um planejamento fatorial 23 com ponto central foi realizado para otimizar a saborizacao do produto, avaliando a adicao de sacarose (50, 85 e 120xa0g.L-1), corante natural carmim cochonilha (0,5; 1,0 e 1,5xa0g.L-1) e aroma natural de morango (0,10; 0,25 e 0,40xa0g.L-1). Diferentes concentracoes da cultura Bio Rich (L. acidophilus, Bifidobacterium e S. thermophilus) foram testadas (1,00; 0,50 e 0,33xa0g.L-1), ordenando-se sensorialmente conforme a preferencia. Concentracoes do xarope de fruto-oligossacarideos (50 e 100xa0g.L-1) foram avaliadas por meio de aceitacao sensorial e analises microbiologicas. Um leite fermentado sabor morango utilizando, emxa0g.L-1, 0,33 de cultura, 120 de sacarose, 1,5 de corante, 0,4 de aroma e 100 de xarope de fruto-oligossacarideos, foi desenvolvido. O incremento da concentracao de prebiotico influenciou positivamente na preferencia do produto, apresentando indice de aceitacao de 88%; microbiologicamente, aumentou a contagem de L. acidophilus e Bifidobacterium, sendo 1,7 × 107 e 4,8xa0× 106 UFC.mL-1, respectivamente, com 100xa0g.L-1 de prebiotico.

RICE PARBOILING WASTEWATER IN THE MAXIMIZATION OF CAROTENOIDS BIOPRODUCTION BY Phaffia rhodozyma

The interest in carotenoid production from natural sources has increased based in their possible use as dyes and their powerful biological antioxidant capacity. This study evaluated the use of rice parboiling wastewater (RPW) as an alternative substrate for the bioproduction of carotenoids using the yeast Phaffia rhodozyma and found it to be promising as the only source of nutrients, reaching a concentration of 0.6 mg mL-1 (259.1 mg g-1) in 48 h. To increase the potential use of this industrial effluent, a study of supplementation was carried out to enhance the production of carotenoids using the methodology of experimental design (a 2IV 6-2 fractional factorial design sequenced by a 24 central composite design). The conditions for maximizing the production of carotenoids were (g L-1) malt extract (16.25), peptone (8.75), sucrose (15) and rice parboiling wastewater (87.5), with a pH of 5 at 25 °C and 150 rpm for 144 h, which produced a concentration 5.3 mg mL-1 (628.8 mg g-1).

Síntese de galacto-oligossacarídeos a partir de lactose usando β-galactosidase comercial de Kluyveromyces lactis

The main goal of this work was to study the influence of the reaction parameters on the enzymatic production of galactooligosaccharides (GOS) using the commercial β-galactosidase from Kluyveromycesxa0lactis (Lactozym® 3000xa0L) and lactose as the substrate. A 23 experimental design was proposed, verifying the influence of the temperature (30 to 40xa0°C), lactose concentration (200 to 400xa0mg.mL-1) and enzyme concentration (5 to 10xa0U.mL-1) on the performance of the enzymatic reaction. The assays were carried out at 180xa0rpm and pH 7.0 (0.1xa0M sodium phosphate buffer). The enzyme Lactozym® 3000xa0L presented transgalactosylation activity, reaching a yield of 41.9% and GOS concentration of 167.5xa0mg.mL-1 in a reaction system composed of 400xa0mg.mL-1 of lactose and 5xa0U.mL-1 of enzyme at 30xa0°C and 14xa0h of reaction. Under these conditions the lactose conversion was 65.0%. Higher lactose concentrations favored the transgalactosylation mechanism, whereas the hydrolytic mechanism dominated with lower concentrations.

Síntese enzimática de butirato de isoamila empregando lipases microbianas comerciais

Isoamyl butyrate production was investigated using free and immobilized lipases by esterification of butyric acid with isoamyl alcohol in a solvent-free system and in an organic media. Among the enzymes studied, Lipozyme TL IM was found to be the most active catalyst in n-hexane as a solvent. The effects of different solvents and the amount of water added on conversion rates were studied. A maximum conversion yield of 80% in n-hexano at 48 h was obtained under the following conditions: 3 g L-1 of Lipozyme TL IM, 30 oC, 180 rpm of agitation, isoamyl alcohol to butyric acid molar ratio of 1:1 and acid substrate concentration of 0.06 M.

Determinação de nitrato e nitrito em chás de peles de pescados empregados para tratamento de asma brônquica na região sul do Rio Grande do Sul

The objective of this paper was to determine nitrate and nitrite anions in toasted fish skin tea, which the population of southern Rio Grande do Sul believes to have pharmacological properties for trating asthma. Two methods were compared, an official and one described by Guozhen et al., that has the advantage of not needing reduction of nitrate to nitrite on a Cd column. The samples were the skin of the fish species Balistes capriscus (peixe porco) and Menticirrhus littoralis (papa-terra), both crude and toasted, as traditionally used. The method of Guozhen et al. was used due to its performance (detection limit 0.005 µmol/L NO3- and 0.02 µmol/L - NO2- and mean recuperation of 100 and 97% respectively for each anion) and results similar to those of the official methods under conditions used by the population, the estimated daily intake, of the teas is equivalent to 0.03 to 0.05 mg of nitrate and 0.007 to 0.014 mg of nitrite. These values are in accord with safety recommendations and dont represent a health risk.