Victor Haber Perez

Growth of Escherichia coli under extremely low-frequency electromagnetic fields.

The inflence 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 culturesexposed 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.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.

Bioreactor coupled with electromagnetic field generator : Effects of extremely low frequency electromagnetic fields on ethanol production by Saccharomyces cerevisiae

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.

Kinetics of Gas-Phase Hydrolysis of Ethyl Acetate Catalyzed by Immobilized Lipase

Reactions catalyzed by supported enzymes present important advantages when compared with those in aqueous media or organic solvents: separation of enzymes from substrate is easily accomplished, enzyme stability may be improved, and control of the reaction products is more accurate. We present the experimental results of the kinetic study of ethyl acetate hydrolysis in gaseous phase catalyzed by a commercial immobilized lipase (Lipozyme IM; Novo Nordisk). The hydrolysis reaction was studied as a function of ethyl ester and water partial pressure at a constant temperature of 318 K. The amount of biocatalyst used was varied between 100 and 300 mg, and the reaction was studied in a flow-through glass microreactor. Under the conditions used, water was an important parameter in the gas-phase reaction. Activation energy was 24.8 kJ/mol and the overall order of reaction was one. Finally a Bi-Bi reaction mechanism is proposed.

Trends in Biodiesel Production: Present Status and Future Directions

The use of renewable fuels, an alternative that reduces the generation of greenhouse gases, is one proposal to mitigate the effects that contribute to global warming. Brazil is the fourth largest producer of biodiesel in the world, and growth expectations of the productive capacities have generated huge technological and environmental challenges. In this context, this chapter discusses some of the relevant aspects of biodiesel production in Brazil, including sustainability of raw materials, conventional technology limitations, and further presents technological alternatives as strategies that will guide the future directions which can result in processes with greater environmental and economic returns.

BIOCATÁLISE HETEROGÊNEA EM FASE SÓLIDO/GÁS: PRINCÍPIOS E APLICAÇÕES

Enzymatic conversion of gaseous substrates into products in aquo-restricted media, using enzymes or whole cells (free and immobilized) as biocatalysts, constitutes a promising technology for the development of clearer processes. Solid-gas systems offer high production rates for minimal plant sizes, allow important reduction of treated volumes, and permit simplified downstream processes. In this review article, principles and applications of solid-gas biocatalysis are discussed. Comparisons of its advantages and disadvantages with those of the organic- and aqueous-phase reactions are also presented herein.

Screening of Metarhizium spp. strains for anticancer indolizidine alkaloid production and its rapid detection by MS analysis

Six fungi strains (M. anisopliae 3935, 4516, 4819, PL57, PL43 and M. flavoviride CG291) were studied regarding their ability to produce an anticancer indolizidine alkaloid. The culture process was carried out in Shaken flask at 26oC and 200 rpm using three different culture medium containing oat meal extract supplemented with glucose and DL-lysine or Czapek culture medium. The mycelial extracts produced by Metarhizium spp. cultures were directly submitted to electrospray ionization mass spectrometry (ESI-MS) analysis and the highest alkaloid concentration (approximately, 6 mg.L-1) was reached when M. anisopliae 3935 was tested.

The Realm of Lipases in Biodiesel Production

Lipases are the enzymes known for the hydrolytic activity on carboxylic fatty ester bonds. The industrial interest in lipases is due to their application in a wide array of products: in detergents and cleaning products, in pharmaceutical applications, in the food industry, and on the production of biodiesel. Biodiesel, i.e. short-chain-acyl fatty ester, is mainly produced via the transesterification of fatty-acyl glycerides or esterification of fatty acids, both reactions with a short chain alcohol. Lipases can catalyze both said reactions with high specificity, producing biodiesel at high yields at low temperature. With the significant advances in biodiesel production over the last decades, coupled with a strong industrial partnership, the costs of utilizing lipases as catalysts have dropped significantly. The production of lipases became popularized in the industry due to advances not only in the reaction mechanisms, and in better understanding of lipase-producing microorganisms, but to cost-effective utilization practices. Immobilization is the practice responsible for the initial breakthrough innovation that allowed efficient reutilization of lipases, thus reducing the cost per batch. There was, and still there is, numerous advances in the development of immobilizing matrices and novel utilization pathways of immobilized enzymes available in the literature. More recently, other methods of using lipase in biodiesel production have been developed, e.g. via the utilization of whole-cell and fermented solid with lypolytic activity, and by the use of lipase in liquid formulations. Over the last years, there has been an increased interest in developing next-generation biodiesel, i.e., the one produced from alternative lipid feedstock, such as microbial and residual lipids, and by utilizing ethanol as acyl agent, instead of methanol. There has also been prominent advances in the reactor engineering aspect of lipase-derived biodiesel, by promoting more efficient batch processes, and the development of lower-cost continuous processing. The present chapter reviews the recent literature in the important field of using lipases in biodiesel production, and critically describes the opportunities and challenges present in such applications.