Obtenção de biossurfactante por Bacillus subtilis ATCC (9372) a partir de melaço de cana-de-açúcar

Abstract

Surfactants are amphiphilic molecules capable of interacting with fluids of different characteristics such as polar and nonpolar mixtures, and capable of reducing the surface tension at the liquid / air interface; due to that fact it presents application in several areas. The concern with the environment preservation has driven researches with the objective of getting less pollutant products and processes. Thus, this work aimed to study the obtaining and characterization of the biosurfactant produced by the Bacillus subtilis as a biocatalyst process and sugar cane molasses as a means of culture. The research methodology used to assess the significant effects on the amount of biomass and biosurfactant produced was the Box-Behnken experimental design technique with three study factors: pH; initial inoculum concentration and percentage of supplementation. The means of fermentation, molasses solution, was purified, sterilized and had its pH adjusted, as well as its supplementation and inoculation with the Bacillus subtilis, according to the experimental design proposed. Fermentation took place under an orbital shaking of 150 rpm for 144 hours at a temperature of 35 ° degrees Celsius. After fermentation the biosurfactant was recovered from the means of fermentation using up centrifugation, precipitation with methanol solvent and an oven for drying. To evaluate the fermentation process, and the influence of the study variables in the process AR, ART, ° Brix, pH and biomass analyses were performed at the beginning and at the end of the fermentation; the quantification in mass of the biosurfactant recovered and dried was also made. The biosurfactant obtained was characterized by the emulsifying index reading in IR. The results showed that the range of investigated pH values and the percentage of the initial inoculum did not influence significantly the production of the biomass, but the supplementation promoted the growth of the microorganism. It may also be noted that the three factors studied influenced the biosurfactant production and that the supplementation interfered positively, as well as the biomass. Through the emulsification index it was possible to observe the formation of the emulsified layer in the biosurfactant interface/ soybean oil, indicating the emulsifying capacity of the biosurfactant obtained; and through the IR it can be suggested that the biosurfactant obtained is surfactin.