Avaliação do efeito de diferentes solventes orgânicos na eficiência da recuperação da pululana sintetizada por Aureobasidium pullulans

Abstract

The fungus Aureobasidium pullulans demonstrates remarkable resistance to harsh environments, including wet, dry, irradiated, desert, and arctic conditions. This microorganism could produce pululan biopolymer, which has several industrial applications. In the food industry, pullulan is used as an edible coating for fruits and stabilizer in beverages. In the cosmetic industry, it is employed in face masks and as a stabilizer in creams. In the pharmaceutical industry, pullulan is applied as a coating for drug capsules. In addition to these sectors, pullulan finds application in several other industries due to its properties. Production still encounters some difficulties, such as scale-up and recovery of the product from the fermented broth. Therefore, the study of the production and recovery of pullulan using different post-fermentation organic solvents aims to evaluate the kinetics of the microorganism and the impact of the solvents on the recovery efficiency of the biopolymer. Initially, parameters such as the specific growth rate (μ) were determined under conditions controlled by a Stirred Tank Reactor (STR) bioreactor. In addition, the conversion factors Yx/s, Yp/s, and Yp/x were calculated to evaluate the average yield of the microorganism in the production of pullulan, by substrate and biomass from the substrate used, respectively. The recovery of pululan from the fermented broth was performed with ethyl alcohol, methyl alcohol, isopropyl alcohol, isoamyl alcohol, toluene, ethyl acetate, hexane and cyclohexane to evaluate the efficiency in post-fermentation product recovery. A literature review, extensive research and analysis of experimental data using academic databases, scientific journals and specialized literature on fermentation were conducted. The results show that some organic solvents such as cyclohexane, hexane, ethyl acetate, isoamyl alcohol and toluene were not able to perform the separation due to molecular interactions incompatible with the biopolymer. Alcohols, particularly isopropyl alcohol, proved to be the most efficient in the recovery of pululan, reaching 17.59g/L. The specific growth rate approached 0.24 per hour, while the fermentation kinetics showed that the production of polymer takes a certain time to start when the cells reached approximately 10g/L from 15 hours of fermentation beginning to increase the concentration of product. In this way, this study contributes to the understanding of the biotechnological processes involved, but also the practical relevance in the search for more effective and sustainable methods in industrial production.