This work deals with the transesterification of palm oil with ethanol in a solvent free system using lipase from different sources (Thermomyces lanuginosus, Pseudomonas fluorescens, Burkholderia cepacia, Penicillium camembertii, and Candida antarctica, porcine pancreatic) immobilized on hybrid support polysiloxane-poly-(vinyl alcohol). This is an exceptional option for the Brazilian biodiesel production, because both palm oil and ethanol are readily available in the country. The enzyme source showed strong influence on the transesterification yields, and the best performance was attained with the lipase from Pseudomonas fluorescens that reached almost full conversion (=98 %) in less than 24 h of reaction. The purified product (biodiesel) was straw yellow in color and essentially odorless. Purity of the fatty acid ethyl ester was found to be high having no glycerol bound as verified by NMR 13 C (APT, attached proton test). In addition, the other properties such as low water content (0.02%), specific gravity (0.8), and viscosity (4.97 cSt) are in accordance with specifications recommended by the ASTM D6751 to be used as biofuel.

The ability of three commercially available lipases to mediate the hydrolysis of the soybean oil to yield concentrated of essential fatty acids was evaluated. The tested lipases were from microbial (Candida rugosa and Thermomyces lanuginosa) and animal cells (Porcine pancreatic lipase). In terms of free fatty acids, microbial lipases were more effective to promote the enzymatic hydrolysis of the soybean oil (over 70%) than the porcine pancreatic lipase (24%). In spite of this, porcine pancreatic lipase (PPL) showed the most satisfactory specificity towards both essential fatty acids and was, therefore, chosen to carry out additional studies. An experimental design was performed taking into consideration the enzyme and NaCl amounts as independent variables. The main effects were fitted by multiple regression analysis to a linear model and maximum fatty acids concentration could be obtained using 3.0 wt% of lipase and 0.08 wt% of NaCl. The mathematical model representing the hydrolysis degree was found to describe adequately the experimental results. Under these conditions, concentrations of 29.5 g/L and 4.6 g/L for linoleic and linolenic acids, respectively, were obtained.

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The effect of extremely low frequency (ELF) magnetic fields on ethanol production by Saccharomyces cerevisiae using sugar cane molasses was studied during batch fermentation. The cellular suspension from the fermentor was externally recycled through a stainless steel tube inserted in two magnetic field generators, and consequently, the ethanol production was intensified. Two magnetic field generators were coupled to the bioreactor, which were operated conveniently in simple or combined ways. Therefore, the recycle velocity and intensity of the magnetic field varied in a range of 0.6-1.4 m s(-1) and 5-20 mT, respectively. However, under the best conditions with the magnetic field treatment (0.9-1.2 m s(-1) and 20 mT plus solenoid), the overall volumetric ethanol productivity was approximately 17% higher than in the control experiment. These results made it possible to verify the effectiveness of the dynamic magnetic treatment since the fermentations with magnetic treatment reached their final stage in less time, i.e., approximately 2 h earlier, when compared with the control experiment.

The influence of extremely low-frequency (ELF) electromagnetic fields on Escherichia coli cultures in submerse fermentation was studied. The fermentation processes were carried out recycling the culture medium externally through a stainless steel tube inserted in a magnetic field generator (solenoid). The exposure time and electromagnetic induction were varied in a range of 1 to 12 h and 0.010 to 0.10 T, respectively, according to a Box-Wilson Central Composite Designs of face centered with five central points. Growth of E. coli could be altered (stimulated or inhibited) under magnetic fieldinduced effects. E. coli cultures exposed at 0.1 T during 6.5 h exhibited changes in its viability compared to unexposed cells, which was 100 times higher than the control. The magnetic field generator associated with the cellular suspension recycle is a new way of magnetic treatment in fermentation processes and could be appropriate to industrial scale up.