Structural and compositional diversity of biosurfactants produced by a novel strain of Sporosarcina luteola ME44 from oil reservoir.

The urealytically active microorganism Sporosarcina luteola induces the precipitation of metals, which has attracted attention in biomineralization, bioremediation, and industrial waste recycling. Herein, we report a novel biosurfactant-producing strain of S. luteola ME44 isolated from Chinese Oilfield. The structure, composition, and surface activity of the biosurfactants produced by S. luteola ME44 were investigated by using a combination of the high-performance liquid chromatography, time-of-flight mass spectrometry, and surface tensiometer. The biosurfactant extracted by strain ME44 was identified as surfactin with five variants and the yield was 1010 ± 60 mg⋅L-1 . This is the first report on the structural composition and surface activity of biosurfactants isolated from the S. luteola. It extended our knowledge about the role of the species S. luteola in the ecosystem of extreme natural environments such as oil reservoir. In addition, S. luteola ME44 showed bioprecipitation properties for metal ions Cd(II), Cu(II), Zn(II), and Ag(I), which indicated the application potential of S. luteola in the field of bioremediation.

A new biosurfactant-producing strain, Fictibacillus nanhaiensis ME46, isolated from an oil field in China.

The genus Fictibacillus contains twelve species significant in the synthesis of cellulose-degrading enzymes and phenylalanine dehydrogenase, isolated mainly from marine sedimentary environments. Here, we report a new biosurfactant-producing strain, Fictibacillus nanhaiensis ME46, isolated from Daqing oil field in China. The biosurfactant extracted from Strain ME46 was determined as surfactin, one of the representative families of lipopeptide biosurfactants. The yield of the surfactin produced by strain ME46 was 0.62 g·L-1 as determined by high-performance liquid chromatography, and the critical micelle concentration (CMC) of the surfactin was estimated to be about 68 mg·L-1 and the surface tension at CMC was 35.1 mN·m-1. This study extended our knowledge about the role of the species Fictibacillus nanhaiensis in the ecosystem of natural environments such as the oil field.

Structural Diversity of the Lipopeptide Biosurfactant Produced by a Newly Isolated Strain, Geobacillus thermodenitrifcans ME63.

The genus Geobacillus is active in degradation of hydrocarbons in thermophilic and facultative environments since it was first reported in 1920. Here, we report a new strain, Geobacillus thermodenitrificans ME63, isolated from an oilfield with the ability of producing the biosurfactant. The composition, chemical structure, and surface activity of the biosurfactant produced by G. thermodenitrificans ME63 were investigated by using a combination of the high-performance liquid chromatography, time-of-flight ion mass spectrometry, and surface tensiometer. The biosurfactant produced by strain ME63 was identified as surfactin with six variants, which is one of the representative family of lipopeptide biosurfactants. The amino acid residue sequence in the peptide of this surfactin is N-Glu → Leu → Leu → Val → Leu → Asp → Leu-C. The critical micelle concentration (CMC) of the surfactin is 55 mg L-1, and the surface tension at CMC is 35.9 mN m-1, which is promising in bioremediation and oil recovery industries. The surface activity and emulsification properties of biosurfactants produced by G. thermodenitrificans ME63 showed excellent resistance to temperature changes, salinity changes, and pH changes.

Adsorption characteristics of residual oil on amphiphilic chitosan derivative.

In this study, a novel chitosan-based polymeric surfactant, H-Oleoyl-Carboxymethyl chitosan was used as a coagulation agent for cleaning residual oil. The characteristics of H-Oleoyl-Carboxymethyl chitosan were investigated by FTIR and XRD. And the adsorption capacities of chitosan and H-O-CMCS for removing the residue oil from the wastewater of oil extraction have been investigated. H-O-CMCS exhibited a greater rate than chitosan in cleaning the residual oil from the wastewater of oil extraction at the optimum conditions. Equilibrium study, Langmuir/Freundlich adsorption models and the pseudo first- and second-order kinetic models were applied to describe the mechanism of adsorption experiments. The experimental data fitted well with the Langmuir model and the second-order kinetic model. Regeneration studies, using by the roasting and rinsing method, were undergone for three successive adsorption/desorption processes. H-O-CMCS still retained the residual oil removal capacity after regeneration.

Effect of molecular weight on the oleoyl-chitosan nanoparticles as carriers for doxorubicin.

Self-assembled oleoyl-chitosan (OCH) nanoparticles based on chitosan with different molecular weights (5kDa, 38kDa and 300kDa) were prepared by oil/water (O/W) emulsification method. The nanoparticles have spherical shape and the mean diameters were 131.8nm, 255.3nm and 334.1nm, respectively. Doxorubicin hydrochloride (DOX) was efficiently loaded into OCH nanoparticles and shown to be sustained release in PBS. The loading efficiency and the DOX release rate increased as the molecular weight of chitosan decreased. The blank OCH nanoparticles showed no cytotoxicity to mouse embryo fibroblasts and human lung cancer cell line A549. The inhibitory rates of DOX-loaded OCH nanoparticle suspension to A549 cells significantly outperformed that of DOX solution, and decreased with the increase of molecular weight. These results revealed the promising potential of low molecular weight OCH nanoparticles as carriers for antitumor agents.