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.

Silva SN ，Farias CB ，Rufino RD ，Luna JM ，Sarubbo LA ... -  《-》

Optimization of environmental factors for improved production of rhamnolipid biosurfactant by Pseudomonas aeruginosa RS29 on glycerol.

A biosurfactant producing Pseudomonas aeruginosa RS29 (identified on the basis of 16S rDNA analysis) with good foaming and emulsification properties has been isolated from crude oil contaminated sites. Optimization of different environmental factors was carried out with an objective to achieve maximum production of biosurfactant. Production of biosurfactant was estimated in terms of surface tension reduction and emulsification (E24) index. It was recorded that the isolated strain produced highest biosurfactant after 48 h of incubation at 37.5 °C, with a pH range of 7-8 and at salinity <0.8% (w/v). Ammonium nitrate used in the experiment was the best nitrogen source for the growth of biomass of P. aeruginosa RS29. On the other hand sodium and potassium nitrate enhanced the production of biosurfactant (Surface tension, 26.3 and 26.4 mN/m and E24 index, 80 and 79% respectively). The CMC of the biosurfactant was 90 mg/l. Maximum biomass (6.30 g/l) and biosurfactant production (0.80 g/l) were recorded at an optimal C/N ratio of 12.5. Biochemical analysis and FTIR spectra confirmed that the biosurfactant was rhamnolipid in nature. GC-MS analysis revealed the presence of C(8) and C(10) fatty acid components in the purified biosurfactant.

Saikia RR ，Deka S ，Deka M ，Sarma H ... -  《-》

Characterisation, surface properties and biological activity of a biosurfactant produced from industrial waste by Candida sphaerica UCP0995 for application in the petroleum industry.

The development of less toxic, biodegradable, surfactants, such as biosurfactants, is a key strategy for acquiring environmentally friendly compounds. The aim of the present study was to employ an optimised medium containing 9% ground nut oil refinery residue and 9% corn steep liquor for the production of a biosurfactant by Candida sphaerica. Fermentation was carried out at 28 °C and 200 rpm for 144 h. Biosurfactant yield was 9 g/l. The biosurfactant reduced the surface tension of the medium to 25 mN/m, with a critical micelle concentration of 0.025%. The product demonstrated stability with regard to surface tension reduction and emulsification in a range of temperatures (5-120 °C) and pH values (2-12) as well as tolerance to high concentrations of NaCl (2-10%). Hydrophobicity tests indicate two possible insoluble substrate uptake mechanisms: direct interfacial uptake and biosurfactant-mediated transfer (cell contact with emulsified or solubilised hydrocarbons). The biosurfactant was characterised as an anionic glycolipid consisting of 70% lipids and 15% carbohydrates and demonstrated no toxicity to the microcrustacean Artemia salina or the vegetables Brassica oleracea, Solanum gilo, Lactuca sativa L. and Brassica oleracea L. The biosurfactant recovered 95% of motor oil adsorbed to a sand sample, demonstrating considerable potential for use in bioremediation processes, especially in the petroleum industry.

Luna JM ，Rufino RD ，Sarubbo LA ，Campos-Takaki GM ... -  《-》

Synthesis, characterization, and oil recovery application of biosurfactant produced by indigenous pseudomonas aeruginosa WJ-1 using waste vegetable oils.

Xia WJ ，Luo ZB ，Dong HP ，Yu L ，Cui QF ，Bi YQ ... -  《-》

Production of rhamnolipids in solid-state cultivation: Characterization, downstream processing and application in the cleaning of contaminated soils.

Camilios Neto D ，Meira JA ，Tiburtius E ，Zamora PP ，Bugay C ，Mitchell DA ，Krieger N ... -  《-》