Biocatalytic esterification of fatty acids using a low-cost fermented solid from solid-state fermentation with Yarrowia lipolytica.

This study aimed to evaluate the use of a lyophilized fermented solid (named solid enzymatic preparation, SEP), with lipase activity, as a low-cost biocatalyst for esterification reactions of fatty acids present in acid raw materials for biodiesel synthesis. The SEP was obtained by solid-state fermentation (SSF) of soybean bran using the strain of Yarrowia lipolytica IMUFRJ 50682 and contains the lipases secreted by this yeast. The esterification reaction of ethanol and the predominant fatty acids present in different acid oil sources for biodiesel production (oleic, linoleic, stearic and palmitic acids) was investigated. Oleic acid conversion of above 85% was obtained after 24 h, using 30 wt% of SEP and ethanol/oleic acid molar ratio of 1, at 30 °C, in a reaction medium with and without solvent (n-hexane). Similar results were achieved with stearic (79%), palmitic (82%) and linoleic (90%) acids. The reusability of SEP was investigated over ten successive batches by washing it with different solvents (ethanol, water or n-hexane) between the cycles of ethyl oleate synthesis. Washing with water allowed the SEP to be reused for six cycles maintaining over 80% of the conversion reached in the first cycle. These results show the potential of this biocatalyst to reduce the content of free fatty acids in acid oils for biodiesel synthesis with a potential to be applied in a broad plethora of raw materials.

Kinetic modeling and equilibrium studies during cadmium biosorption by dead Sargassum sp. biomass.

A basic investigation on the removal of cadmium(II) ions from aqueous solutions by dead Sargassum sp. was conducted in batch conditions. The influence of different experimental parameters; initial pH, shaking rate, sorption time, temperature and initial concentrations of cadmium ions on cadmium uptake was evaluated. Results indicated that cadmium uptake could be described by the Langmuir adsorption model, being the monolayer capacity negatively affected with an increase in temperature. Analogously, the adsorption equilibrium constant decreased with increasing temperature. The kinetics of the adsorption process followed a second-order adsorption, with characteristic constants increasing with increasing temperature. Activation energy of biosorption could be calculated as equal to 10 kcal/mol. The biomass used proved to be suitable for removal of cadmium from dilute solutions. Its maximum uptake capacity was 120 mg/g. It can be considered an optimal result when compared to conventional adsorbing materials. Thus Sargassum sp. has great potential for removing cadmium ions especially when concentration of this metal is low in samples such as wastewater streams.

Batch and fixed-bed column biosorption of manganese ion by sargassum filipendula

This paper presents experimental data of the biosorption of manganese onto Sargassum filipendula in both batch and fixed-bed column systems. Batch equilibrium data were used for nonlinear fittings of the Langmuir and Freundlich isotherms. A mathematical model based on mass balances in the fluid and in the sorbent was applied to represent the experimental fixed-bed column data. The utilization of isotherm parameters from the batch experiments in the breakthrough model implied a significant mismatch in relation to the laboratory data. Alternatively, additional fixed-bed column data provided new parameters for the isotherm evaluation, and the corresponding simulated profile of the breakthrough curve reached better agreement to the experimental results.

Ácido graxo ômega 3 docosahexaenóico (DHA:C22:6 n-3) e desenvolvimento neonatal: aspectos relacionados à sua essencialidade e suplementação / Omega 3 fatty acid (DHA:22:6 -3) and neonatal development: aspects related to its essenciality and supplementation

Os ácidos graxos poliinsaturados da série n-3 são importantes no desenvolvimento e funcionamento do sistema nervoso central. O ácido graxo docosahexaenóico (DHA; C22:6 n-3) está presente no leite materno, mas não na maioria das fórmulas lácteas comerciais. O objetivo da presente revisão foi examinar as principais informações na literatura científica com relação à essencialidade dos ácidos graxos poliinsaturados da série n-3 (`alfa'-linolênico) e seu homólogo superior, o ácido docosahexaenóico, para o desenvolvimento, bem como o impacto da suplementação deste em formulações lácteas comerciais. Dadas as inúmeras controvérsias e limitações dos estudos até então realizados, não é possível afirmar se a inclusão de DHA nas formulações comerciais confere benefícios a curto ou longo-prazo para o desenvolvimento neuronal dos lactentes, que não possam ou simplesmente não recebem o leite materno...