Immobilized Cells Research Articles

Carbon nanomaterial properties help to enhance xylanase production from recombinant Kluyveromyces lactis through a cell immobilization method.

Carbon nanomaterials, due to their catalytic activity and high surface area, have potential as cell immobilization supports to increase the production of xylanase. Recombinant Kluyveromyces lactis used for xylanase production was integrated into a polymeric gel network with carbon nanomaterials. Carbon nanomaterials were pretreated before cell immobilization with hydrochloric acid (HCl) treatment and glutaraldehyde (GA) crosslinking, which contributes to cell immobilization performance. Carbon nanotubes (CNTs) and graphene oxide (GO) were further screened using a Plackett-Burman experimental design. Cell loading and agar concentration were the most important factors in xylanase production with low cell leakage. Under optimized conditions, xylanase production was increased by more than 400% compared to free cells. Immobilized cell material containing such high cell densities may exhibit new and unexplored beneficial properties because the cells comprise a large fraction of the component. The use of carbon nanomaterials as a cell immobilization support along with the entrapment method successfully enhances the production of xylanase, providing a new route to improved bioprocessing, particularly for the production of enzymes. KEY POINTS: • Carbon nanomaterials (CNTs, GO) have potential as cell immobilization supports. • Entrapment in a polymeric gel network provides space for xylanase production. • Plackett-Burman design screen for the most important factor for cell immobilization.

A novel surface treatment of carbon fiber with Fenton reagent oxidization for improved cells immobilization and xylitol fermentation

A novel treatment of carbon fiber (CF) with Fenton reagent was used to improve its surface properties, immobilization efficiency (IE), and xylitol yield. The process realized the oxidized treatment and the introduction of iron ions on CF. The specific surface area, surface acidity and degree of moisture increased, while the contact angle and the pH of the point of zero charges decreased after the treatment by Fenton reagent. Notably, the high-affinity iron ions introduced by the modification that enhanced the intracellular coenzyme cycle for xylitol accumulation due to the higher NADPH/NADP+ ratio and NADPH content. In addition, introduced iron ion on the CF promoted the reduction of intracellular reactive oxygen species level and mitochondrial membrane polarization level. As a result, compared to the untreated-CF, the IE and xylitol yield were increased by 86.15 % and 43 % with the treated CF, respectively. Using Fenton reagent to treat CF provided an excellent method to prepare biocompatible immobilized carriers for industrial production of xylitol.

Application of an alginate-based edible coating with bacteriocin-producing Lactococcus strains in fresh cheese preservation

Edible coatings incorporated with bacteriocin-producing lactic acid bacteria (LAB) can provide an alternative natural preservation method as they can offer an additional microbiological protection to food products. The bacteriocin-producing strains Lactococcus lactis L3A21M1 and Lc. garvieae SJM17 isolated from artisanal Azorean cheeses were incorporated into an edible fresh-cheese coating composed of alginate, maltodextrin and glycerol. The immobilization of Lactococcus cells into the coating had no negative effect on their viability and antibacterial activity throughout 10 days storage at 4 °C and 10 °C. The application of coating with immobilized Lactococcus cells on cheeses reduced significantly (p < 0.05) the contamination by Listeria monocytogenes on surface and prevented the growth of mesophilic bacteria by the 6th and 8th day of storage at 4 °C. Moreover, the coating reduced moisture and weight losses of fresh cheeses during storage, without affecting the pH and titratable acidity. The coating also prevented the migration of L. monocytogenes from the surface into the cheeses. These findings indicate that alginate-maltodextrin-glycerol formulation provided an excellent matrix to support Lactococcus cells viability and bacteriocin production. This bioactive coating can act as protective antimicrobial barrier in fresh cheeses by reducing bacterial contamination after processing.

Modification of wheat straw to improve the caproate production in a cell immobilized system

Wheat straw is a favorable cell carrier in the caproate fermentation system, yet its smooth surface limits the biofilm formation. In this study, the modification of wheat straw was conducted using three different chemical methods and the influence of its modified surface on the caproate fermentation was investigated. Results showed that the sodium hydroxide was the optimum reagent for modification of wheat straw, where both the external and internal surfaces were effectively modified, resulting in 34.4% increased specific surface area. The highest caproate production of 21.1 g/L was obtained in fed-batch fermentation, which was ascribed to the formation of a thick biofilm on the modified carrier. Moreover, the crystallinity index of the carrier increased during the fed-batch fermentation, implying that the modified wheat straw was a stable matrix for cell immobilization. This study provides an effective way for efficient caproate production through modification of wheat straw.

Miniaturized System for Tumor Cell Detection and Differentiation

This paper presents an automated, miniaturized, and portable system capable of detection and differentiation of cultured tumor cells and non-malignant cells. It is also capable of differentiation between single tumor cells and cell clusters. It is noninvasive, and operates without the need for cell labelling, device functionalization, and cell immobilization. The system is composed of a microfabricated electrical impedance spectroscopy (EIS) based sensor, a custom printed circuit board (PCB) and software running on a computer. The custom PCB replaces costly and specialized impedance analysis instruments and the software with a graphical user interface facilitates automated decisions - thus making the system easy to operate. Performance was tested with three human breast cell lines: healthy cell line BPE-3 and tumor cell lines MCF-7 and MDA-MB-231. The system successfully detected and differentiated between the three cell lines. The observed difference between the healthy cell line and the two tumor cell lines was more pronounced. And as cell detection and differentiation is based solely on biophysical properties of cells, disadvantages arising from affinity-based methods can be avoided. The presented miniaturized system possesses the potential to be developed into a low cost, portable and mass producible device for automated detection of CTCs in blood samples at point of care locations. The figure shows the microfabricated sensor consisting of a microfluidic channel with gold electrodes on the channel sidewalls employed to probe biological cells: (A) final device with PDMS layer to be bonded. (B) Microscope image of an electrode pair. (Scale bars 5mm and 100 μm).

Can oxysterols work in anti-glioblastoma therapy? Model studies complemented with biological experiments

Despite the progress made in recent years in the field of oncology, the results of glioblastoma treatment remain unsatisfactory. In this paper, cholesterol derivatives - oxysterols - have been investigated in the context of their anti-cancer activity. First, the influence of three oxysterols (7-K, 7β-OH and 25-OH), differing in their chemical structure, on the properties of a model membrane imitating glioblastoma multiforme (GBM) cells was investigated. For this purpose, the Langmuir monolayer technique was applied. The obtained results clearly show that oxysterols modify the structure of the membrane by its stiffening, with the 7-K effect being the most pronounced. Next, the influence of 7-K on the nanomechanical properties of glioblastoma cells (U-251 line) was verified with AFM. It has been shown that 7-K has a dose-dependent cytotoxic effect on glioblastoma cells leading to the induction of apoptosis as confirmed by viability tests. Interestingly, significant changes in membrane structure, characteristic for phospholipidosis, has also been observed. Based on our results we believe that oxysterol-induced apoptosis and phospholipidosis are related and may share common signaling pathways. Dysregulation of lipids in phospholipidosis inhibit cell proliferation and may play key roles in the induction of apoptosis by oxysterols. Moreover, anticancer activity of these compounds may be related to the immobilization of cancer cells as a result of stiffening effect caused by oxysterols. Therefore, we believe that oxysterols are good candidates as new therapeutic molecules as an alternative to the aggressive treatment of GBM currently in use.

Experimental Study on Sand Stabilization Using Bio-Cementation with Wastepaper Fiber Integration.

Recently, green materials and technologies have received considerable attention in geotechnical engineering. One of such techniques is microbially-induced carbonate precipitation (MICP). In the MICP process, CaCO3 is achieved bio-chemically within the soil, thus enhancing the strength and stiffness. The purpose of this study is to introduce the wastepaper fiber (WPF) onto the MICP (i) to study the mechanical properties of MICP-treated sand with varying WPF content (0–8%) and (ii) to assess the freeze–thaw (FT) durability of the treated samples. Findings revealed that the ductility of the treated samples increases with the increase in WPF addition, while the highest UCS is found with a small fiber addition. The results of CaCO3 content suggest that the WPF addition enhances the immobilization of the bacteria cells, thus yielding the precipitation content. However, shear wave velocity analysis indicates that a higher addition of WPF results in rapid deterioration of the samples when subjected to freeze–thaw cycles. Microscale analysis illuminates that fiber clusters replace the solid bonding at particle contacts, leading to reduced resistance to freeze–thaw damage. Overall, the study demonstrates that as a waste material, WPF could be sustainably reused in the bio-cementation.

Nanocarriers-based immobilization of enzymes for industrial application.

Nanocarriers-based immobilization strategies are a novel concept in the enhancement of enzyme stability, shelf life and efficiency. A wide range of natural and artificial supports have been assessed for their efficacy in enzyme immobilization. Nanomaterials epitomize unique and fascinating matrices for enzyme immobilization. These structures include carbon nanotubes, superparamagnetic nanoparticles and nanofibers. These nano-based supports offer stable attachment of enzymes, thus ensuring their reusability in diverse industrial applications. This review attempts to encompass recent developments in the critical role played by nanotechnology towards the improvement of the practical applicability of microbial enzymes. Nanoparticles are increasingly being used in combination with various polymers to facilitate enzyme immobilization. These endeavors are proving to be conducive for enzyme-catalyzed industrial operations. In recent years the diversity of nanomaterials has grown tremendously, thus offering endless opportunities in the form of novel combinations for various biotransformation experimentations. These nanocarriers are advantageous for both free enzymes and whole-cell immobilization, thus demonstrating to be relatively effective in several fermentation procedures.

Removal of triclocarban from treated wastewater using cell-immobilized biochar as a sustainable water treatment technology

Triclocarban (TCC), an emerging endocrine disruptor, has been commonly found in municipal treated wastewater. Pseudomonas fluorescens MC46 (MC46), an effective TCC-degrading bacterium, could be applied to remove TCC from wastewater. In addition, application of a cell immobilization technique could possibly enhance its removal performance. This study examined microbial cells immobilized on waste biochar (from wood vinegar production) as a highly effective advanced wastewater treatment unit for TCC removal. TCC removal was investigated from real wastewater samples using the following treatments: biochar only, cell-immobilized biochar, and free cell systems in batch (short-term) and semi-batch (long-term) modes. The TCC adsorption capacities of original and potassium hydroxide-modified biochars (no cells) were 8.43 and 9.17 mg/g, respectively. During the batch experiment, the cell-immobilized modified biochar exhibited the highest TCC removal, 79.80%, in the model TCC solution. Five-cycle semi-batch experiments were utilized to investigate the reusability and performance of the treatment systems. After five cycles, the cell-immobilized modified biochar still achieved stable TCC removal (52%) due to the integration of adsorption and biodegradation. Free MC46 cells and biochars (no MC46 cells) only removed 32% and 2% of TCC, respectively, due to cell washout/death and sorbent exhaustion. This important work clearly demonstrates the significant potential for the future utilization of cell-immobilized biochars in a sustainable wastewater treatment system. Furthermore, the use of renewable agro-industrial wastes aid in the development of a strong circular bio-based economy.

The Metabolic Flux Probe (MFP)-Secreted Protein as a Non-Disruptive Information Carrier for 13C-Based Metabolic Flux Analysis.

Novel cultivation technologies demand the adaptation of existing analytical concepts. Metabolic flux analysis (MFA) requires stable-isotope labeling of biomass-bound protein as the primary information source. Obtaining the required protein in cultivation set-ups where biomass is inaccessible due to low cell densities and cell immobilization is difficult to date. We developed a non-disruptive analytical concept for 13C-based metabolic flux analysis based on secreted protein as an information carrier for isotope mapping in the protein-bound amino acids. This “metabolic flux probe” (MFP) concept was investigated in different cultivation set-ups with a recombinant, protein-secreting yeast strain. The obtained results grant insight into intracellular protein turnover dynamics. Experiments under metabolic but isotopically nonstationary conditions in continuous glucose-limited chemostats at high dilution rates demonstrated faster incorporation of isotope information from labeled glucose into the recombinant reporter protein than in biomass-bound protein. Our results suggest that the reporter protein was polymerized from intracellular amino acid pools with higher turnover rates than biomass-bound protein. The latter aspect might be vital for 13C-flux analyses under isotopically nonstationary conditions for analyzing fast metabolic dynamics.

Immobilization of Cells of Hydrocarbon-oxidizing Bacteria for Petroleum Bioremediation Using New Materials

Immobilization of Cells of Hydrocarbon-oxidizing Bacteria for Petroleum Bioremediation Using New Materials

Whole cell immobilization of recombinant E. coli cells by calcium alginate beads; evaluation of plasmid stability and production of extracellular L-asparaginase

ABSTRACT L-asparaginase from Escherichia coli is an important therapeutic agent in the treatment of childhood acute lymphoblastic leukemia. In this study, the secretory production of a recombinant form of L-asparaginase enzyme was investigated in E. coli cells immobilized in calcium alginate beads. The protein expression was determined for the immobilized cells with two different initial cell concentrations and compared with the free cells. The maximum enzyme activity of the released asparaginase was achieved in the culture medium of the alginate beads with the lower cell density at 3 days after immobilization. Total asparaginase activity of the enzymes released into the culture medium or entrapped in the alginate beads was 315.8 U, which exhibited about 2-fold higher activity than the extracellular asparaginase activity of the conventional free cells (162.3 U). A maximum plasmid stability of 49%, which was 25-fold higher than the free cells, was obtained by the immobilized cells.

Combining acetone-butanol-ethanol production and methyl orange decolorization in wastewater by fermentation with solid food waste as substrate

Simultaneously producing acetone-butanol-ethanol (ABE) and decolorizing Methyl orange (MO) by fermentation with solid food waste (SFW) was studied. During the batch fermentation with MO concentration from 100 mgL−1 to 1000 mgL−1, carbon source utilization efficiency was above 93% with yields of acetone, butanol and ethanol being 0.13 gg-1, 0.23 gg-1 and 0.04 gg-1, respectively. During the repeated fermentation with the bagasse as the cell immobilization material, carbon source utilization efficiencies were all above 90% in the first 5 cycles fermentation. The maximum butanol and ABE concentration were 12.8 gL-1 and 22.1 gL-1, respectively. The solvent yield of acetone, butanol and ethanol were around 0.13 gg-1, 0.25 gg-1 and 0.06 gg-1, respectively. The MO decolorization had no negative effect on the ABE production and the decolorization efficiencies were all above 99% during batch fermentation or repeated fermentation with electrons transferred from intracellular to extracellular by mediator with the help of azo reductase to decolorize MO.

Propionic acid production from glycerol in immobilized cell bioreactor using an acid-tolerant strain of Propionibacterium acidipropionici obtained by adaptive evolution

Propionic acid (PA) production from agro-industrial residues using propionibacteria has gained interest as an alternative to fossil-based process. Microbial production is however characterized by product inhibition, lowering the product titers and productivity. In this study, Propionibacterium acidipropionici DSMZ4900 was subjected to adaptive evolution to tolerate higher acid concentrations. The strain adapted to growth in medium spiked with 20 g/L PA exhibited improved product titer (16.8 vs 8.72 g/L) and productivity (0.52 vs 0.17 g/L·h) with glycerol as carbon source in batch fermentations. It was immobilized on polyethyleneimine coated recycled glass beads Poraver® and used for fermentations in recycle batch mode with increasing glycerol concentration and decreasing pH, respectively. Doubling yeast extract concentration raised PA yield and productivity by >1.5 fold. Glycerol at 100 g/L was completely consumed to give ∼58 g/L PA at yield of 0.64 mol/mol and productivity of 0.28 g/L·h at pH 6.5. Decreasing fermentation pH to 5.0 increased PA productivity to 0.23 g/L·h from 0.14 g/L·h at pH 6.0 with 20 g/L glycerol, while immobilized cells exhibited no growth. The study shows combination of adaptive evolution and immobilization of cells to result in a robust system for PA fermentation at high glycerol concentration and lower pH.

Immobilization of transgenic plant cells towards bioprinting for production of a recombinant biodefense agent.

Transgenic rice cells (Oryza sativa) producing recombinant butyrylcholinesterase (BChE) as a prophylactic/therapeutic against organophosphate nerve agent poisoning, cocaine toxicity, and neurodegenerative diseases like Alzheimer's were immobilized in a polyethylene glycol-based hydrogel. The cells were sustained for 14 days in the semi-solid matrix, undergoing a growth phase from days 0-6, a BChE production phase in sugar-free medium from days 6-12, and a growth/recovery phase from days 12-14. Throughout this period, the cells maintained similar viability to those in suspension cultures and displayed analogous sugar consumption trends. The rice cells in the hydrogel also produced a significant amount of active BChE, comparable to the levels produced in liquid cultures. A considerable fraction of this BChE was secreted into the media, allowing for easier product separation. To the best of our knowledge, this proof-of-concept is the first report of immobilization of recombinant plant cells for continuous production of high-value heterologous proteins. This work serves as a foundation for further investigation towards plant cell bioprinting and the development of a simple, efficient, robust, modular, and potentially field-deployable bioreactor system for the manufacture of biologics.

Maximizing the enzyme immobilization of enzymatic glucose biofuel cells through hierarchically structured reduced graphene oxide

The number of immobilized glucose oxidase (GOx) molecules is considerably increased by the structural modification of reduced graphene oxide (rGO), and the performance of enzymatic biofuel cells (EBFCs) is positively affected by the modification process. To do this, new rGO with three-dimensional open porous structure is formed by spray freeze drying method (sprGO), while tetrathiafulvalene (TTF) as mediator, and GOx are sequentially immobilized onto sprGO. To improve the loading amount of catalyst, rGO structure is modified to open porous sprGO structure possessing numerous anchoring sites, after which gelatin film crosslinked by glutaraldehyde is fabricated onto sprGO to prevent any losses of other components (sprGO/[TTF-GOx]/crosslinked-gelatin). Specific surface area and charge transfer resistance of sprGO are quantitatively measured, and the actual amount of immobilized GOx and the performance of EBFC using this catalyst are electrochemically examined. With this, it is found that the amount of GOx immobilized in sprGO/[TTF-GOx]/crosslinked-gelatin is twice better that in rGO/[TTF-GOx]/crosslinked-gelatin. More specifically, EBFC using this catalyst shows open circuit voltage of 0.85 V and maximum power density of 380 μW/cm2, and this is 1.4 times better than that using rGO/[TTF-GOx]/crosslinked-gelatin. These results indicate that the amount of immobilized GOx strongly affects the performance capabilities of EBFCs.

P–114 Correlation of GSTM1 polymorphism and oxidative stress with male infertility

Abstract Study question Is GSTM1 polymorphism a putative biomarker of male infertility. Is there a possible correlation between GSTM1 presence, oxidative stress and male infertility? Summary answer A possible correlation may be established between GSTM1 polymorphism, and sperm mobility and morphology. Additionally oxidative potential may also be associated with fertility. What is known already Approximately 7% of men worldwide are affected by male infertility, which contributes to 40–50% of all infertility cases. Basic sperm analysis remains the main procedure of diagnosing male infertility, although there is still doubt whether it provides accurate clinical outcomes More accurate tests are essential for the diagnosis of male infertility. Oxidative stress is involved in the etiology of male infertility, with 30% to 80% of infertile men having increased levels of sperm free radicals. Recent research has shown that oxidative stress when combined with GSTM1-null genotype negatively affected the sperm quality of infertility group compared to the control group. Study design, size, duration Ninety semen samples were collected and divided into 2 groups. The study group consisted of sperm samples from 51 men identified as infertile according to WHO guidelines(case group).Sperm samples from 39 men with normal sperm count parameters (control group) were used for the control group. Participants/materials, setting, methods For all samples a sperm diagram was performed. and DNA was extracted. Polymerase chain reaction with specific for GSTM1 gene primers followed by agarose electrophoresis was applied to detect the presence of polymorphism. The MiOXSYS method was used to detect the oxidative potential. Main results and the role of chance This study shows that in the control group the presence of polymorphism was associated with a reduced number of immobile sperm cells (p = 0,035) while it appears to affect the normal morphology of the sperm(p = 0,042). In the infertility group the presence of the gene was significantly correlated with age(p = 0.046). No statistically significant difference was observed for the presence of the polymorphism between the 2 groups.In addition, we investigated the effect of oxidative potential with the MiOXSYS system and its relationship with sperm parameters. It was found that the two groups differed significantly when measuring oxidative potential, and that oxidoreduction potential affects sperm concentration/ml, total sperm count, type B motility and viscosity in the infertile male group. Limitations, reasons for caution A larger sample size could increase the accuracy of the results. Wider implications of the findings: Studying the relation of the oxidative stress with sperm parameters may lead to the establishment of a genetic profile of increased risk of infertility, which would be of major importance especially in cases of idiopathic infertility. Trial registration number Not applicable

Immobilization of beneficial microbe Methylobacterium aminovorans in electrospun nanofibre as potential seed coatings for improving germination and growth of groundnut Arachis hypogaea

Seed inoculation with microbial cells is one of the potential invigouration techniques for enhancing the emergence and growth of plants. Herein, we approached a new localized delivery of beneficial microbial cells (Methylobacterium) by invigorating seeds with electrospun Polyvinyl alcohol (PVA) nanofibre containing microbial cells. Methylobacterium is a growth promoting bacteria that has recently drawn attention in agriculture, particularly for drought management. PVA was used in this research because of its electrospinnability and biodegradability. Encapsulation study shows effective immobilization of bacteria cells (Methylorubrum aminovorans) in PVA nanofibre. SEM and TEM characterization further confirmed the entrapment of microbial cells. The microbial plating enumeration reveals 6.6 × 105 CFU g−1 of nanofibre to the initial loading population of 1 × 108 CFU. Viability of nanofibre encapsulated bacterial cells under ambient environment found 1.85 × 105 CFU g−1, 2.2 × 104 CFU g−1 and 1.2 × 104 CFU g−1 on 10, 20 and 30 days after storage, respectively. In vitro bio-efficacy study exhibits that the seeds coated by PVA nanofibres containing M. aminovorans recorded higher germination, root & shoot length, seedling vigor, drymatter production, plant biomass, plant root volume, nodule numbers and fresh weight of nodules. The study concludes that microbial cells could be immobilized in electrospun nanofibre for extended shelf-life of microbial cells and as an effective seed coating for localized delivery.

System optimization of an embedding protocol to immobilize cells from Candida bombicola to improve the efficiency of sophorolipids production

This study introduces the implication of immobilization technology in the fermentation process of sophorolipids (SLs) production by Candida bombicola. Firstly, an evaluation system was established for the performance of embedding immobilization and subsequently applied to guide the optimization of operating conditions for sodium alginate immobilization. Correspondingly, the SLs titer increased from 11.4 g/L to 14.6 g/L. Secondly, polyvinyl alcohol was introduced for composite embedding to improve the stability of immobilized beads. Then exogenous addition of 1.5% diatomite further enhanced the fermentation performance of immobilized cells, thereby increasing the SLs titer to 35.9 g/L, which was 2.1 times higher than the original immobilized cells method. Finally, the immobilized cells were tested for three repeated batches of SLs fermentation. Compared to the free cells fermentation, the SLs productivity and substrate conversion rate were increased by 35.5% and 9.1%, respectively. The obtained results showed high potential for application on an industrial scale.

Uranium removal from complex mining waters by alginate beads doped with cells of Stenotrophomonas sp. Br8: Novel perspectives for metal bioremediation

Uranium-containing effluents generated by nuclear energy industry must be efficiently remediated before release to the environment. Currently, numerous microbial-based strategies are being developed for this purpose. In particular, the bacterial strain Stenotrophomonas sp. Br8, isolated from U mill tailings porewaters, has been already shown to efficiently precipitate U(VI) as stable U phosphates mediated by phosphatase activity. However, the upscaling of this strategy should overcome some constraints regarding cell exposure to harsh environmental conditions. In the present study, the immobilization of Br8 biomass in an inorganic matrix was optimized to provide protection to the cells as well as to make the process more convenient for real-scale utilization. The use of biocompatible, highly porous alginate beads for Br8 cells immobilization resulted the best alternative when investigating by a multidisciplinary approach (High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM), Environmental Scanning Electron Microscopy (ESEM), Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance, etc.) several consolidated entrapment methods. This biomaterial was applied to complex real U mining porewaters (containing 47 mg/L U) in presence of an organic phosphate source (glycerol-2-phosphate) to produce reactive free orthophosphates through Br8 phosphatase activity. Uranium immobilization rates around 98 % were observed after one cycle of 72 h. In terms of U removal ability as a function of biomass, Br8-doped alginate beads were determined to remove up to 1199.5 mg U/g dry biomass over two treatment cycles. Additionally, optimized conditions for storing Br8-doped beads and for a correct application were assessed. Results for U accumulation kinetics and HAADF-STEM/ESEM analyses revealed that U removal by the immobilized cells is a biphasic process combining a first passive U sorption onto bead and/or cell surfaces and a second slow active biomineralization. This work provides new practical insights into the biological and physico-chemical parameters governing a high-efficient U bioremediation process based on the phosphatase activity of immobilized bacterial cells when applied to complex mining waters under laboratory conditions.