Produção de biossurfactante por Pseudomonas Aeruginosa empregando óleo de soja residual

Abstract

This work has as objective to investigate the production of biosurfactant employing strain of Pseudomonas aeruginosa using as source of carbon residual soybean oil from several foods frying. In the first assay the Pseudomonas aeruginosa were used ATCC 9027, isolated Pseudomonas aeruginosa from Landfarming REDUC (PALR) and a Pseudomonas aeruginosa PACL strain, isolated from a lagoon hydrocarbon-contaminated soil. To evaluate the results of the assay a two levels complete factorial experimental design was used, studying as variables the microorganism strain, the concentrations of residual soybean oil (OSR), the concentrations of nitrate of ammonium (AN) and brewery residual yeast (YRB). The experiments were performed in 500-mL Erlenmeyer flasks containing 50 mL of production medium, at 170 rpm and 30±1ºC, for a 48-hour fermentation period. Biosurfactant production has been monitored by measurements of rhamnose concentration (RM), surface tension (TS) and emulsifying activity (IE). The P. aeruginosa PALR, ATCC 9027 and the PALC were capable to reduce the superficial tension of the initial medium of 61± 1dynes/cm for 33,9; 28 e 26 dynes/cm, to produce g/L 0,25; 0,77 e 1,39 of rhamnose, with emulsification index of 60, 100 and 100%, respectively. The results obtained by experimental design proved that isolated Pseudomonas aeruginosa PALC presented potential greater to produce biossurfactante, being, therefore, selected for the other experiments carried out in at study. The optimization of OSR, AN, and RBY was accomplished by a central composite design (CCD) and their results analyzed by surface response analysis. The best planned results, was located on the central point, have corresponded to 22 g/L of RSO, 5.625 g/L of AN, and 11.5 g/L of RBY. The greater obtained concentration of rhamnose after 48 hours of fermentation, was 2,3 g/L with emulsifying activity of 100%. Employed the best result obtained in PCC, was determined, using a bioreactor, the best conditions of aeration rate (vvm) and agitation speed (rpm) using a complete factorial experimental design. In the optimized conditions, of 0,5 vvm (KLa of 10,2 h-1) and speed of agitation of 550 rpm, were obtained the superficial tension of 26,0 dyne/cm and synthesis of rhamnose of 3,26 g/L. Under the optimized conditions, the biosurfactant production from a mixture of waste frying soybean oil was compared with non used soybean oil (NUSO) and waste soybean oils used to fry in separate meats (MFSO), salty (SAFSO), and potatoes (POFSO). Finally was made a kinetic study, seeking to determine a model to represent the experimental data of rhamnose production and the nutrients consumption. After recovery and purification of the biosurfactant the rhamnose concentration increased in 80% in the final product, that is, 6,8 g/L.