Production, characterization, evaluation and toxicity assessment of a Bacillus cereus UCP 1615 biosurfactant for marine oil spills bioremediation.

In this study, Bacillus cereus was cultivated in a mineral medium composed of 2% frying oil and 0.12% peptone to produce a biosurfactant. The production was scaled up from flasks to 1.2-, 3.0- and 50-L bioreactors, where surface tension achieved 28.7, 27.5 and 32 mN/m and biosurfactant concentration 4.3, 4.6 and 4.7 g/L, respectively. The biosurfactant was characterized as anionic, while nuclear magnetic resonance, thin-layer chromatography and gas chromatography analyses revealed its lipopeptide nature. Toxicity tests showed survival rates of the fish Poecilia vivipara and the bivalve Anomalocardia brasiliana higher than 90% and 55%, respectively, thus suggesting the use of this biosurfactant in marine environment depollution. Moreover, the biosurfactant stimulated the growth of autochthonous microorganisms independently of the presence of motor oil in bioassays performed in seawater. These results demonstrate that the biosurfactant is biocompatible and has potential for industrial-scale production and application to bioremediation of oil spills-polluted marine environment.

Characterization and application of a biosurfactant isolated from Candida utilis in salad dressings.

This study aimed at characterizing a biosurfactant from Candida utilis, and use it in the preparation of salad dressings. The biosurfactant was produced in mineral medium supplemented with 6% glucose and 6% waste frying canola oil. The crude biosurfactant was then tested for stability in different conditions of pH, salt concentration, heating time and temperature. The critical micelle dilution, chemical composition, and structural analysis were determined. The compound was resistant to extreme conditions and presented stable surface tension and emulsification activity in alkaline pH and was characterized as a carbohydrate-lipid-protein complex showing the best formulation and consistency at 0.7% (w/v) with guar gum indicating potential applicability in food emulsions.

Production and characterization of a biosurfactant produced by Streptomyces sp. DPUA 1559 isolated from lichens of the Amazon region

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.

Production and characterization of a biosurfactant produced by Streptomyces sp. DPUA 1559 isolated from lichens of the Amazon region.

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.

Antimicrobial and anti-adhesive potential of a biosurfactant Rufisan produced by Candida lipolytica UCP 0988.

In the last years, researches developed with biosurfactants for application in the medical area have been revealing the promising biological activities of these biomolecules. In this work the antimicrobial and anti-adhesive properties of a biosurfactant Rufisan isolated from the yeast Candida lipolytica UCP 0988, growth in a medium supplemented with ground nut refinery residue was determined against several microorganisms. The biosurfactant was able to reduce the water surface tension from 70 to 25.3 mN/m and showed a critical micelle concentration (CMC) of 0.03%. The biosurfactant was isolated after 72 h of fermentation and was tested in concentrations varying from 0.75 to 12 mg/l. The highest antimicrobial activities were observed against Streptococcus agalactiae, Streptococcus mutans, Streptococcus mutans NS, Streptococcus mutans HG, Streptococcus sanguis 12, Streptococcus oralis J22 at a concentration superior to the biosurfactant critical micelle concentration. Moreover, the biosurfactant showed anti-adhesive activity against most of the microorganisms tested. As far as we know, this is the first compilation of data on antimicrobial and anti-adhesive activities of a biosurfactant obtained from a Candida strain against such a broad group of microorganisms. The results obtained in this work showed that the biosurfactant from C. lipolytica is a potential antimicrobial and/or anti-adhesive agent for several biomedical applications.

Glycerol as substrate for the production of biosurfactant by Pseudomonas aeruginosa UCP0992.

In this work the influence of the carbon source concentration, of the type and concentration of the nitrogen source and of the cultivation conditions (temperature, aeration and agitation speed) in mineral medium formulated with glycerol was studied for biosurfactant production by Pseudomonas aeruginosa UCP0992. The kinetics of microorganism growth and biosurfactant production have been described for the medium supplemented with 3% glycerol and 0.6% NaNO(3), at 28 degrees C during 120 h under 200 rpm, showing a growth-associated production. The isolated biosurfactant corresponded to a concentration of 8.0 g/l after 96 h. The medium surface tension was reduced to 27.4 mN/m and the emulsification index of hexadecane reached 75-80% after 72 h. A CMC of 700 mg/l and an interfacial tension against hexadecane of 2 mN/m were obtained. The biosurfactant showed stability when submitted at 90 degrees C during 2 h, and thermal (4-120 degrees C) and pH (4-12) stability regarding the surface tension reduction and the emulsification capacity of vegetable oils and hydrocarbons, and tolerance under high salt concentrations (2-10%). The biosurfactant was characterized as a group of rhamnolipids with anionic nature. The crude biosurfactant did not show toxicity against the microcrustacean Artemia salina and the cabbage (Brassica oleracea), while the isolated biosurfactant showed toxicity against the microcrustacean at the CMC. The application of the biosurfactant in diesel recovery from sand was demonstrated by removal percentiles above 85%. The results obtained in this work are noteworthy for possible biosurfactant production from glycerol with potential of application in the environment.

Physical and rheological characterisation of polyethylene glycol-cashew-nut tree gum aqueous two-phase systems.

The characterisation of the polyethylene glycol-cashew-nut tree gum aqueous two-phase system is described. Factors which affect the phase diagram including polymer molecular mass, pH and temperature were analysed. The physico-chemical properties of the system such as density, viscosity, volume ratio and phase separation times were also described. The characteristics of the system studied indicate it to be very attractive as a separation technique.

Bioemulsifier production in batch culture using glucose as carbon source by Candida lipolytica.

The yeast Candida lipolytica IA 1055 produced an inducible extracellular emulsification activity while utilizing glucose at different concentrations as carbon source during batch fermentation at 27 degrees C. In all glucose concentrations studied, maximum production of emulsification activity was detected in the stationary phase of growth, after pH reached minimal values. The bioemulsifier isolated was a complex biopolymer constituting proteins, carbohydrates, and lipids. The results obtained in this work show that the biosynthesis of a bioemulsifier is not simply a prerequisite for the degradation of extracellular hydrocarbon.

New aqueous two-phase system based on cashew-nut tree gum and poly(ethylene glycol).

The characterisation of a new system based on cashew-nut tree gum, a branched acidic heteropolysaccharide found in Brazil, and poly(ethylene glycol) (PEG) was studied. Phase diagrams are provided for the PEG-cashew-nut tree gum system. The influence of PEG molecular mass, tie-line length and pH on bovine serum albumin (BSA) partition was investigated. Protein partition coefficient was little influenced by changing PEG molecular mass. Increasing the tie-line length decreased the partition. Increasing the pH also raised the BSA partition coefficient. It is shown that systems formed by PEG and cashew-nut tree gum may be considered as an interesting alternative for use in protein purification.

The use of babassu oil as substrate to produce bioemulsifiers by Candida lipolytica.

Candida lipolytica IA 1055 produced an extracellular emulsifier when using babassu oil as its sole carbon source during batch and fed batch fermentations at 27 degrees C. Emulsification activity was detected after 60 h of growth in all conditions studied. The bioemulsifier was isolated after 144 h of fermentation from the best condition studied. The biopolymer seems to be a polysaccharide-protein-lipid complex.

Estudo comparativo da produçäo de bioemulsificantes por amostras de Candida lipolytica / Comparative study on bioemulsifiers produced by Candida lipolytica strains

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