Produção de ramnolipídeos por Pseudomonas aeruginosa AP029-GLVIIA usando glicose como substrato e aplicações

Abstract

Biosurfactants are amphiphilic compounds of microbial origin, which have aroused as an alternative to the use of chemical surfactants, due to the fact that they are synthesized from petroleum derivatives, therefore, very aggressive to the environment. In addition to, biological surfactants have properties similar to the chemical surfactants and also have some advantages over them such as biodegradability and stability in different pH, temperature and salinity conditions. In face of this situation, several studies have been developed in order to make the production of biosurfactants viable for commercialization. The most researches aim to analyze the production of these compounds using different renewable sources and investigate their surfactant properties. The rhamnolipids, which are biosurfactants produced by bacteria and belonging to the group of glycolipids, are applied in several industrial areas due to its various properties as emulsifying, solubilizing, wetting, so on. Thus, this work aims to verify the production of rhamnolipid by Pseudomonas aeruginosa AP029-GLVIIA, changing the following parameters: the concentration of glucose (10, 18 and 26 g / L) and the inoculum percentage (3, 10 and 17%) for 72 hours. Along with time the cell growth (X), the glucose concentration consumed (S), the produced rhamnolipid (P), the pH of the system and the production of total proteins were assessed. Five trials were performed and the best condition (26 g / L glucose and 3 ml inoculum) produced 0.838 ± 0.064 g/ L ramnolipid in 24 hours, biomass conversion factor in product (YP/X) of 0.260 g/g, substrate conversion factor in product (YP/S) of 0.034 g/g and product productivity (PP) of 0.021 g/L∙h. At this assay, the biomass reached the highest value among all cultures (2.5 ± 0.041 g/L), pH ranged from 5.8 to 8 and substrate consumption reached 82.45% at the end of the experiment. From the best outcome, there were studied the emulsification index and the emulsifying activity with six different solvents: kerosene, hexadecane, toluene, soybean oil, corn oil and motor oil. The last one presented the best response with emulsification index of 77.55% in the first 24 hours and high emulsifying stability, 2.23 U. Then, the efficiency of the biosurfactant in the removal of oil present in sand was evaluated in 16.8% and the antimicrobial activity of the ramnolipid against fungal species were determined. Therefore, this outcome shows out the ability of the ramnolipid to inhibit fungi of the species Candida tropicalis and Candida albicans. At last, the obtained results prove the potential of the rhamnolipid produced for biotechnological applications.