Optimization of acetoin production by Hanseniaspora guilliermondii using experimental design

The synthesis of acetoin in YM medium and under aerobic conditions by Hanseniaspora guilliermondii was studied. Experimental design and surface response analysis were employed to evaluate the influence of glucose concentration, temperature and pH on the process. The experiments were carried out in shaking flasks under controlled temperature. Five different levels of initial concentration of glucose, temperature and pH were used with variations from 17 to 81 g/L, from 24 to 36ºC and from 4.0 to 6.0, respectively. The maximum concentration of acetoin was the response obtained. The parameters which affected acetoin production most were initial concentration of glucose and temperature. An empirical model that showed statistically significant and predictive capacity was constructed. The optimum values of glucose concentration and temperature obtained for acetoin production were 63 g/L and 28ºC, respectively

Transesterification of Palm Oil Catalyzed by Pseudomonas fluorescens Lipase in a Packed-Bed Reactor

Transesterification of palm oil with ethanol catalyzed by Pseudomonas fluorescens lipase immobilized on epoxy-polysiloxane-polyvinyl alcohol composite (epoxy-SiO2-PVA) was performed in a continuous packed-bed reactor (PBR). Two strategies were used for improving the miscibility of the substrates: the addition of the organic solvent tert-butanol and the surfactant Triton X-100. Results were compared to those obtained in a solventless reactor, which displayed a biphasic system that passed through the reactor. Using this system, the ethyl ester yield of 61.6 +/- 1.2% was obtained at steady state. Both Triton X-100 and tert-butanol systems were found to be suitable to promote the miscibility of the starting materials; however, the use of Triton X-100 reduced the yield to levels lower than 20%, because of the enzyme desorption from the support surface, as confirmed by scanning electron microscopy analysis. The best performance was found for the reactor running in the presence of tert-butanol which resulted in a stable operating system and an average yield of 87.6 +/- 2.5%. This strategy also gave high biocatalyst operational stability, revealing a half-life of 48 days and an inactivation constant of 0.6 X 10(-3) h(-1).Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

Chronic leucine supplementation did not change the food intake and water ingestion of ob/ob mice.

<p>The food intake and water ingestion of ob/ob mice (<i>n</i> = 7) were assessed for 20 consecutive days. During the first 10 days, the mice received water to drink (H₂O, white bar), followed by 10 days of leucine supplementation in the drinking water (Leucine, black bar).</p

Hypothalamic mRNA expression of genes involved in the BCAA metabolism and energy balance regulation.

<p>Gene expression was assessed in mice receiving a low-fat diet (A, <i>n</i> = 10 per group) or a high-fat diet (B, <i>n</i> = 9-10 per group). *, significantly different (<i>P</i> < 0.05) from control group. †, <i>P</i> = 0.0532 versus control group.</p

Acute oral leucine administration induced phosphorylation of p70S6K in the hypothalamus.

<p>Bar graphs showing the quantification of the phosphorylation of p70S6K in the hypothalamus of mice that received oral gavage of water (CON group, <i>n</i> = 9) or leucine solution (LEU group, <i>n</i> = 9). The data were normalized to the expression of α-actinin. *, significantly different (<i>P</i> < 0.05) from the CON group.</p

Oral Leucine supplementation acutely increased food intake.

<p>A. Oral gavage of a leucine solution increased the 24 h food intake (Day 3 and Day 4) compared to the days when the animals received gavage of water (Day 1 and Day 2). B. No changes in body weight were observed among the experimental days. *, significantly different (<i>P</i> < 0.05) from D1 and D2 (gavage of water).</p