Produção, recuperação e caracterização de biossurfactantes obtidos por linhagens de Bacillus subtilis UFPEDA 16 e Bacillus safensis 28

Abstract

Biosurfactants are amphiphilic molecules with an extensive capacity to reduce surface tension and unique properties, as they are synthesized extracellularly by microorganisms such as Bacillus subtilis UFPEDA16 and Bacillus safensis 28, Gram-positive and non-toxic bacteria. The use of low-cost substrates that have a high concentration of sugars can reduce biosurfactant production costs. The present study evaluated the production capacity of biosurfactants by Bacillus subtilis UFPEDA 16 and Bacillus safensis 28, using the aqueous extract of mesquite as a substrate, and promoted recovery and characterization of the biosurfactant produced. Biosurfactant production was carried out in a medium with 1% (v/v) mesquite aqueous extract as a substrate for B. subtilis UFPEDA 16, while for B. safensis 28 the medium containing 1% (v/v) extract aqueous mesquite, without and with supplementation of 1% (w/v) yeast extract were analyzed, cultivated in Erlenmeyer flasks shaken in an orbital rotating incubator at 200 rpm, 37°C and aeration ratio of 0.4. Samples were taken at regular times to monitor microbial growth, substrate consumption and biosurfactant production for 120 h of process. Subsequently, a product recovery process was carried out by acid precipitation (HCl at 6N) and extraction by organic solvents (Dichloromethane-Chloroform-Methanol). The recovered biosurfactant was analyzed by high-performance liquid chromatography (HPLC) and Fourier transform infrared spectroscopy (FTIR) to characterize it. In cultivation using the B. subtilis UFPEDA 16 strain, a cell concentration in the exponential phase ([X]) of 2.91 g/L was obtained, cell productivity (Px) of 8.958 mg/L.h, maximum specific growth rate (μmax) of 0.0107 h-1, biosurfactant concentration produced 76.67 mg/L with an emulsification capacity of 80.65% in long chain oils. In the production of B. safensis 28, more favorable results were obtained with the supplemented medium in which the maximum cell concentration in the exponential phase (Xmax) was 4.58 g/L, the productivity in cells (Px) was 30.4 mg/ L.h and maximum specific growth rate (μmax) is 0.0469 h-1. In relation to the biosurfactant produced, a concentration of 130.03 mg/L was obtained with a product productivity (Pp) of 1.08 mg/L.h. However, the biosurfactant had a low emulsification capacity of 55%. Regarding characterization, it was possible to determine that the biosurfactant produced by B. safensis 28 in supplemented medium is in fact a surfactin. Concluding that the strains B. subtilis UFPEDA16 and B. safensis 28 were capable of producing lipopeptide-type biosurfactant from the aqueous extract of mesquite, as an alternative substrate, under the proposed conditions.