ABSTRACT This work investigated the combination of agitation and aeration conditions in a bench-bioreactor to identify the optimal biosurfactant production from substrate based on beet peel and glycerol from a biodiesel process. Thus, a central composite rotatable design (CCRD) and responses were evaluated by response surface methodology (RSM) modeling. The optimal operation values determined were 200 rpm (agitation) and 0.5 vvm (aeration), reaching values of 1931.2 mg/L of crude biosurfactant concentration and 28.37 mN/m of surface tension. For the development of a mathematical model based on an artificial neural network (ANN), the experimental data from each run (CCRD) of the bioreactor were used. The results indicated a topology of 6-6-1 neurons with an excellent predictive capacity of biosurfactant concentration: dispersion plot with R2 of 0.995, and error criteria SSE of 0.31, MSE of 7.29×10-4 and RSME of 2.7×10-2. A soft sensor was then designed in an electronic spreadsheet, computing the biosurfactant production from secondary measurements. Furthermore, the produced biosurfactant showed the ability to remediate oil spreading, evaluated through the appearance of clear zones on the surface of water covered with oil, and also from high emulsification indexes obtained on most of the solvents tested, such as toluene (~65%).

There is a growing interest in microbial lipase production due to its great potential for industrial applications such as food additives, industrial reagents and stain removers, as well as for medical applications. Specially for medical applications a high degree of purity is required, which is accomplished with high resolution chromatographic techniques. Affinity chromatography is considered a very high resolution chromatographic technique. In this work the adsorption isotherms and kinetics of the adsorption of lipase from Geotrichum sp on biospecific resin were determined. The resin was prepared using EAH sepharose 4B gel (Pharmacia), made to react with oleic acid as the specific ligand.The lipase was produced in a five-liter fermenter, with both complex and synthetic media. Fermentation conditions were a temperature of 30°C, an aeration of 1VVM and an agitation of 400 rpm. Maximum lipase activity was around 28 U/ml after 10 hours of fermentation for the complex medium. The kinetic model and parameters were determined by dynamic fitting to experimental results using the fourth-order Runge-Kutta method.