Synthesis and activity of nanosilicates and nanosilicate-entrapped enzymes using biomimetic polymers (original) (raw)
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Journal of Microbiological Methods, 2006
A simple biosurfactant-based hydrophobization procedure for poly(vinyl alcohol) (PVA) cryogels was developed allowing effective immobilization of hydrocarbon-oxidizing bacteria. The resulting partially hydrophobized PVA cryogel granules (granule volume 5 Al) contained sufficient number (6.5 Â 10 3 ) of viable bacterial cells per granule, possessed high mechanical strength and spontaneously located at the interface in water-hydrocarbon system. Such interfacial location of PVA granules allowed high contact of immobilized biocatalyst with hydrophobic substrate and water phase, thus providing bacterial cells with mineral and organic nutrients. As a result, n-hexadecane oxidation efficiency of 51% after 10-day incubation was achieved using immobilized biocatalyst. PVA cryogels with increased hydrophobicity can be used for immobilization of bacterial cultures performing oxidative transformations of water-immiscible organic compounds. Immobilization of in situ biosurfactant producing Rhodococcus bacteria into PVA cryogel is discussed. PVA cryogel granules with entrapped alkanotrophic rhodococcal cells were stable after 10-month storage at room temperature. D
Journal of Petroleum & Environmental Biotechnology, 2014
The degradation of the crude oil in wastewater by each of freely microorganisms and by immobilized them on each of crosslinked poly (vinyl alcohol) hydrogel (CPVA) and its foam (CPVAF) was reported. Also, it was studied by using biosurfactants (Bio s) with free cells. The macroporous CPVAF was prepared by adding CaCO 3 as poreforming agent and epichlorohydrin as crosslinker. The prepared polymers are examining by FTIR, XRD, TGA, DSC and SEM analysis. The microorganisms of B.l., R.e. and P.x. isolated from contaminated effluents were investigated. The ability of these microorganisms to degrade the n-paraffin and PAHs was assessed by GC and HPLC analysis, respectively. Moreover, their stabilities and activities were tested in the growth count of bacteria study. The crosslinked CPVA carrier demonstrated better thermal stability and improvement in the microorganism efficiency with respect to hydrocarbons degradation than these of the CPVAF carrier. Scanning electron microscopy showed the presence of extracellular structures that could play an important role in the immobilization stability of cells on polymers. As well, GC analysis revealed that the percentage biodegradation ability of immobilized cells R.e. on CPVAF for the total n-paraffin was approximately, 100%. While, the HPLC analysis showed that the percentage biodegradation of cells for PAHs was enhancement by immobilized them on CPVA and also, at adding Bio s to them. The results suggest that the potential of using each of CPVA, PVAF as cell carriers and Bio s separately, to free cells to enhancing the biodegradation of petroleum hydrocarbons in an open marine environment.
Polish Journal of Microbiology, 2016
The capability of the biosurfactant-producing strain Rhodococcus wratislawiensis BN38 to mineralize both aromatic and aliphatic xenobiotics was proved. During semicontinuous cultivation 11 g/l phenol was completely degraded within 22 cycles by Rhodococcus free cells. Immobilization in a cryogel matrix was performed for the first time to enhance the biodegradation at multiple use. A stable simultaneous hydrocarbon biodegradation was achieved until the total depletion of 20 g/l phenol and 20 g/l n-hexadecane (40 cycles). The alkanotrophic strain R. wratislawiensis BN38 preferably degraded hexadecane rather than phenol. SEM revealed well preserved cells entrapped in the heterogeneous super-macroporous structure of the cryogel which allowed unhindered mass transfer of xenobiotics. The immobilized strain can be used in real conditions for the treatment of contaminated industrial waste water.
Nanomaterials
Production water is the largest byproduct of the oil industry and must be treated before disposal, either by reinjection or shedding processes, with the purpose of eliminating emulsified crude oil and avoiding the operational and toxic problems associated with it. The objective of this work was to immobilize a hydrocarbon-degrading strain on activated carbons, to evaluate the biocomplex’s capacity for catalyzing hydrocarbons from Oil in Brine emulsions (O/W) simulating produced waters. Activated carbons were prepared and their chemical and porous properties were estimated by XPS, pHPZC and SEM, N2 adsorption, and mercury porosimetry. Biomaterials were synthesized and hydrocarbon removal tests were performed. The basic and neutral carbons immobilized Pseudomonas stutzeri by physisorption in the macroporous space and electrostatic interactions (108–109 UFC∙g−1), while acid materials inhibited bacterial growth. Removal of aromatic hydrocarbons was more efficient using materials (60%–93...
Polish Journal of Microbiology, 2016
The capability of the biosurfactant-producing strain Rhodococcus wratislawiensis BN38 to mineralize both aromatic and aliphatic xenobiotics was proved. During semicontinuous cultivation 11 g/l phenol was completely degraded within 22 cycles by Rhodococcus free cells. Immobilization in a cryogel matrix was performed for the first time to enhance the biodegradation at multiple use. A stable simultaneous hydrocarbon biodegradation was achieved until the total depletion of 20 g/l phenol and 20 g/l n-hexadecane (40 cycles). The alkanotrophic strain R. wratislawiensis BN38 preferably degraded hexadecane rather than phenol. SEM revealed well preserved cells entrapped in the heterogeneous super-macroporous structure of the cryogel which allowed unhindered mass transfer of xenobiotics. The immobilized strain can be used in real conditions for the treatment of contaminated industrial waste water.
Biodegradation of crude oil hydrocarbons by a newly isolated biosurfactant producing strain
Biotechnology & Biotechnological Equipment
New bacterial strain BN66 was isolated by selective enrichment, identified as Bacillus cereus and proved to degrade crude oil, together with biosurfactant synthesis. Free and cryogel immobilized Bacillus cereus cells were involved in a crude oil degradation process. The studied strain degraded 93% of the aliphatic fraction for 48 h. We immobilized cells in two types of cryogels synthesized from high molar mass polyacrylamide or acrylamide precursors and explored the degradation capability and possibility for re-use of the preparations. Reusability tests revealed that the oil degradation ability of immobilized cells was stable after 47 days (28 C and shaker speed 120 rpm) and the degradation rate of immobilized cells was maintained at a high level up to the 20 th cycle of operation. The matrices obtained from high molar mass polyacrylamide appeared to be more suitable due to their ability to keep the cells within the carrier. The cells immobilized in cryogels exhibited more effective degradation for 22 active cycles at semicontinuous mode of operation compared to only three cycles performed by free cells.
Hydrophobic VOC could be treated by biodegradation in a two phase partitioning bioreactor (TPPB) containing a non-aqueous liquid phase (NAPL) with activated sludge after an absorption step. The use of NAPL improved the removal of these compounds. The use of silicone oil as NAPL led to removal yields close to 90 and 75 % for toluene and DMDS, respectively. Silicone oil improved the elimination capacity if compared to other NAPL like DEHA. Microorganisms acclimation was fast and the lag time for toluene consumption was low (8 h) compared to DMDS (40 h). Finally, TPPB appears relevant to overcome some difficulties occurring during the treatment of hydrophobic compounds.
New Approach for n-Hexadecane Biodegradation by Sol-Gel Entrapped Bacterial Cells
Ecological Chemistry and Engineering S
In this study sol-gel hybrid materials in the system SiO2-chitosan (CS) - polyethylene glycol (PEG), as novel structures with potential application in bioremediation were investigated. The organic components - CS and PEG were used as structural modifiers for functionality improvement. The catabolic activity to n-hexadecane of Pseudomonas aeruginosa BN10 free and immobilized cells was estimated. The cell immobilization technique was employed to evaluate its efficiency on biodegradation and protective effect from high levels of hydrocarbons. The characteristics of obtained hybrid materials were investigated via X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Atomic-force microscopy (AFM) analyses. The obtained results revealed that the organic part in the synthesized hybrids is important for microstructure and defined properties creation. The rate of n-hexadecane mineralization by the bacterial strain was influenced by va...