RESUMO
Surfactants are amphipathic compounds containing both hydrophilic and hydrophobic groups, capable to lower the surface or interfacial tension. Considering the advantages of the use of biosurfactants produced by microorganisms, the aim of this paper was to develop and characterize a biosurfactant produced by Streptomyces sp. DPUA1559 isolated from lichens of the Amazon region. The microorganism was cultured in a mineral medium containing 1% residual frying soybean oil as the carbon source. The kinetics of biosurfactant production was accompanied by reducing the surface tension of the culture medium from 60 to values around 27.14 mN/m, and by the emulsification index, which showed the efficiency of the biosurfactant as an emulsifier of hydrophobic compounds. The yield of the isolated biosurfactant was 1.74 g/L, in addition to the excellent capability of reducing the surface tension (25.34 mN/m), as observed from the central composite rotational design when the biosurfactant was produced at pH 8.5 at 28°C. The critical micelle concentration of the biosurfactant was determined as 0.01 g/mL. The biosurfactant showed thermal and pH stability regarding the surface tension reduction, and tolerance under high salt concentrations. The isolated biosurfactant showed no toxicity to the micro-crustacean Artemia salina, and to the seeds of lettuce (Lactuca sativa L.) and cabbage (Brassica oleracea L.). The biochemistry characterization of the biosurfactant showed a single protein band, an acid character and a molecular weight around 14.3 kDa, suggesting its glycoproteic nature. The results are promising for the industrial application of this new biosurfactant.
Assuntos
Streptomyces/metabolismo , Tensoativos/metabolismo , Líquens/microbiologia , Valores de Referência , Sementes/efeitos dos fármacos , Temperatura , Fatores de Tempo , Óleo de Soja/química , Contagem de Colônia Microbiana , Análise de Variância , Espectroscopia de Infravermelho com Transformada de Fourier , Meios de Cultura , Eletroforese em Gel de Poliacrilamida , Fermentação , Concentração de Íons de HidrogênioRESUMO
This study was carried out to evaluate the production of bioemulsifiers by two strains of Candida lipolytica 1055 and 1120 respectively. The results obtained showed that strain 1055 was the best producer in media supplemented with 5 per cent of Babaçu oil and glucose 1 per cent, used as carbon source. By using these carbon sources it was possible to show that the bioemulsifiers were produced by Candida lipolytica in the end of exponential growth phase and begining of stationary growth phase as secondaries metabilites