Resumo

Biosurfactants are amphiphilic molecules, such characteristic enable emulsifying, foaming, detergency and dispersing properties. Their low toxicity and the wide range of potential industrial applications have increased the interest in them. Their large scale production and application however, are currently restricted by the high cost of production. For this reason, in this work was investigated the production of surfactin by Bacillus subtilis 21332 using the liquor of sisal acid hydrolysis, a cheap renewable substrate, this one was evaluated and compared with the production in conventional medium with glucose. Bacillus subtilis ATCC 21332 maintained 4°C was transferred to a nutrient agar and incubated for 24 h at 30 °C, an inoculum was prepared by transferring a loop of cells from the plate to a flask containing nutrient broth. The culture was growth for 9 hours at 30 °C , 150 rpm (OD 610nm 0.52) and 5% (v/v) of this inoculum was transferred to 250 mL erlenmeyer flasks containing 20 mL of production medium (g/L): Na2HPO4, 5.67; KH2PO4, 4.08; FeSO4.7H2O, 0.015; MnSO4.H2O, 0.002; MgSO4.7H2O, 0.197; CaCl2.2H2O, 0.001; with sisal cellulose hydrolysate (4%) as the carbon source and the NH4NO3 (0.05M) as the nitrogen source and the pH adjusted to 6.8-6.9. The cultures were grown at 30°C, 150 rpm for 72 hours and samples were withdrawn to determine pH, reducing sugar content (DNS assay), bacterial growth (viable cell number). The surface tension and critical micelle dilution (CMD) were performed by the Du Nouy ring method. It was found one inversely proportional relationship between the bacterial growth and the surface tension, the pH of medium stayed approximately in 7.0 and the surface tension was lowering from 55.10 mNm-1 to 26.83 mNm-1 in 72 hours. The surface tension values of < 27 mNm-1 indicated that the sisal cellulosic hydrolysate offers good conditions for the production of surfactin. The quantity of surfactin was lower when compared with glucose standard medium, suggesting that the presence of furfurals may interfere with bacterial growth. The sisal hydrolysate showed potential as substrate for the production of surfactin.