Caracterização, análise da estabilidade e valoração de biossurfactantes microbianos para aplicação industrial

Abstract

Biosurfactants are amphipathic molecules, produced mainly by microorganisms. Due to their tensoactive properties, these molecules are used in several industrial sectors such as in oil industry. Its surface-active properties, resistance to extreme environmental conditions, low toxicity and cost are essential factors for biosurfactants introduction in the industrial market. Hence, this study aimed to characterize biosurfactants produced by 15 strains of Bacillus sp. for industrial purposes and evaluate their stability at high temperature, pressure and NaCl concentrations and production cost. The samples were characterized as lipopeptides by Infrared Spectroscopy (FTIR) and identified by mass spectrometry as belonging to the families of surfactin, iturin and fengycin. The molecules activities resisted high temperatures, starting to decompose at 260 °C, as revealed by Differential Scanning Calorimeter (DSC). The biosurfactants reduced the water surface tension to at least 30 mN/m, produced stable water-oil emulsion, and also dispersed oil. After the molecules had been subjected to a 600 bar pressure followed by 121 °C / 15 min, as well as in high concentrations of NaCl (100 g/L, 150 g/L), the tensoactives properties were maintained unchanged. The analyzed biosurfactants acted at low concentrations, showing critical micelle concentrations (CMC) below than 30 mg/L. The yield of biosurfactants was used to calculate the biosurfactants price by accounting the raw materials expenses. The cost per gram was on average R$ 11,69. Despite the high cost, the biosurfactants of this study are advantageous, especially the one produced by strain JAG255, since it was stable under extreme conditions of temperature, pH and salinity, and its CMCs was in the order of 100 x lower than many synthetic surfactants, becoming profitable for the industry counterweighing the low commercial competitiveness.