Microalgal-luffa sponge immobilized disc: a new efficient biosorbent for the removal of Ni(II) from aqueous solution

AIMS: The aim was to develop a new, efficient and cost-effective biosorbent for the removal of heavy metals from aqueous solution. METHODS AND RESULTS: A new biosorbent was developed by immobilizing a unicellular green microalga Chlorella sorokiniana within luffa sponge discs and used for the removal of metal ions from aqueous solution. Microalgal-luffa sponge immobilized discs (MLIDs) removed Ni(II) very rapidly, with 97% of equilibrium loading being reached in 5 min. MLIDs were tested for their potential to remove Ni(II) from aqueous solution in fixed-bed column bioreactor. The regenerated MLIDs retained 92.9% of the initial binding capacity for Ni(II) up to five cycles of reuse. CONCLUSIONS: In this study for the first time, C. sorokiniana biomass immobilized within luffa sponge disc was successfully used as a metal biosorbent for the removal of Ni(II). It appears that MLIDs can be used as an effective biosorbent for efficient removal of Ni(II) or other metals from aqueous solution. SIGNIFICANCE AND IMPACT OF THE STUDY: MLIDs biosorption system was shown to have good biosorption properties with respect to Ni(II). Efficient metal removal ability of MLIDs, low cost and simplicity of the technique used for the preparation of MILDs could provide an attractive strategy for developing high-affinity biosorption system for heavy metal removal.     

The mechanism of cadmium removal from aqueous solution by nonmetabolizing free and immobilized live biomass of Rhizopus oligosporus

A preliminary study on the removal of cadmium by nonmetabolizing live biomass of Rhizopus oligosporus from aqueous solution is presented. The equilibrium of the process was in all cases well described by the Langmuir sorption isotherm, suggesting that the process was a chemical, equilibrated and saturable mechanism which reflected the predominantly site-specific mechanism on the cell surface. A curve of Scatchard transformation plots reflected the covalent nature of Cd²⁺ adsorption by the cells. The maximum cadmium uptake capacities were 34.25 mg/g for immobilized cells and 17.09 mg/g for free cells. Some factorial experiments in shake flasks were performed in order to investigate the effect of different initial cadmium concentrations and biomass concentrations on the equilibrium. Experimental results showed a reverse trend of the influence of the immobilized and free biomass concentration on the cadmium specific uptake capacity. The immobilized cells had a higher specific cadmium uptake capacity with increasing biomass concentrations compared to free cells. In a bioreactor, the cadmium uptake capacity of immobilized cells (q_max = 30.1–37.5 mg/g) was similar to that observed in shake flask experiments (q_max = 34.25 mg/g) whereas with free cells the bioreactor q_max of 4.8–13.0 mg/g; was much lower than in shake flasks (q_max = 17.09 mg/g), suggesting that cadmium biosorption by immobilized cells of R. oligosporus might be further improved in bigger reactors. EDAX and transmission electron microscopic experiments on the fungal biomass indicated that the presence of Cd²⁺ sequestrated to the cell wall was due to bioadsorption.     

Application of Arthrospira (Spirulina) platensis biomass for silver removal from aqueous solutions

The cyanobacterium Arthrospira (Spirulina) platensis was used to study the process of silver biosorption. Effects of various parameters such as contact time, dosage of biosorbent, initial pH, temperature, and initial concentration of Ag(I) were investigated for a batch adsorption system. The optimal biosorption conditions were determined as pH 5.0, biosorbent dosage of 0.4 g, and initial silver concentration of 30 mg/L. Equilibrium adsorption data were analyzed by the Langmuir and Freundlich models – however, the Freundlich model provided a better fit to the experimental data. The kinetic data fit the pseudo-second-order model well, with a correlation coefficient of 0.99. The analysis of thermodynamic parameters (ΔG°, ΔH° and ΔS°) revealed that the adsorption process of silver ion by spirulina biomass was exothermic and spontaneous (ΔG° < 0), and exothermic (ΔH° < 0) process. The biosorption capacity of biomass A. platensis serves as a basis for the development of green technology for environmental remediation.     

Production of Fungal Biomass Immobilized Loofa Sponge (FBILS)-discs for the Removal of Heavy Metal Ions and Chlorinated Compounds from Aqueous Solution

A white rot basidiomycete, Phanerochaete chrysosporium, was immobilized on loofa sponge (FBILS) discs. It removed ca. 37 and 71 mg Cd (II) g⁻¹ from 50 and 200 mg l⁻¹ aqueous solutions and up to 89% of 4-chloroanisole from a 10 mg l⁻¹ aqueous solution. FBILS are physically strong and chemically recalcitrant, resisting temperature, mechanical agitation, and variations in pH without alteration to shape, structure or texture.     

Immobilization of blue green microalgae on loofa sponge to biosorb cadmium in repeated shake flask batch and continuous flow fixed bed column reactor system

Summary An indigenous strain of blue green microalga, Synechococcus sp., isolated from wastewater, was immobilized onto loofa sponge discs and investigated as a potential biosorbent for the removal of cadmium from aqueous solutions. Immobilization has enhanced the sorption of cadmium and an increase of biosorption (21%) at equilibrium was noted as compared to free biomass. The kinetics of cadmium biosorption was extremely rapid, with (96%) of adsorption within the first 5 min and equilibrium reached at 15 min. Increasing initial pH or initial cadmium concentration resulted in an increase in cadmium uptake. The maximum biosorption capacity of free and loofa immobilized biomass of Synechococcus sp. was found to be 47.73 and 57.76 mg g⁻¹ biomass respectively. The biosorption equilibrium was well described by Langmuir adsorption isotherm model. The biosorbed cadmium was desorbed by washing the immobilized biomass with dilute HCl (0.1 M) and desorbed biomass was reused in five biosorption–desorption cycles without an apparent decrease in its metal biosorption capacity. The metal removing capacity of loofa immobilized biomass was also tested in a continuous flow fixed-bed column bioreactor and was found to be highly effective in removing cadmium from aqueous solution. The results suggested that the loofa sponge-immobilized biomass of Synechococcus sp. could be used as a biosorbent for an efficient removal of heavy metal ions from aqueous solution.     

Repeated removal of cadmium and zinc from an industrial effluent by waste biomass Sargassum sp.

Waste biomass Sargassum sp. biosorbed 100% of Cd²⁺ and 99.4% of Zn²⁺ from a 3 and 98 mg l^–1 solution (pH 4.5), respectively, at the end of four serial experiments. Of the five desorbents studied in consecutive adsorption/desorption cycles, CaCl₂ 0.05 M eluted nearly 40% of both metals and decreased the biosorption in only 8% and 17% of Cd²⁺ and Zn²⁺, respectively. Although NaOH desorbent improved the heavy metal uptake from the second cycle onwards, it did not elute metals from the pre-loaded biomass.     

Hexavalent chromium removal from aqueous solutions by a novel powder prepared from Colocasia esculenta leaves

In this study, batch removal of hexavalent chromium from aqueous solutions by powdered Colocasia esculenta leaves was investigated. Batch experiments were conducted to study the effects of adsorption of Cr(VI) at different pH values, initial concentrations, agitation speeds, temperatures, and contact times. The biosorbent was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectrometer analysis. The biosorptive capacity of the adsorbent was dependent on the pH of the chromium solution in which maximum removal was observed at pH 2. The adsorption equilibrium data were evaluated for various adsorption isotherm models, kinetic models, and thermodynamics. The equilibrium data fitted well with Freundlich and Halsey models. The adsorption capacity calculated was 47.62 mg/g at pH 2. The adsorption kinetic data were best described by pseudo-second-order kinetic model. Thus, Colocasia esculenta leaves can be considered as one of the efficient and cheap biosorbents for hexavalent chromium removal from aqueous solutions.     

Hepatocyte-specific porous polymer-scaffolds of alginate/galactosylated chitosan sponge for liver-tissue engineering

Porous scaffolds of alginate/galactosylated chitosan (ALG/GC) sponges were prepared by lyophilization for liver-tissue engineering. Primary hepatocytes in ALG/GC sponges showed higher cell attachment and viability than in alginate alone owing to the specific interaction of the asialoglycoprotein receptors on hepatocyte with the galactose residues on ALG/GC sponges. Improvements in spheroid formation and long-term liver-specific functions of the immobilized hepatocyte were also observed in ALG/GC sponge.     

Anti-Adhesive Properties of Calcium Alginate from Sargassum fusiforme against Particulate Matter-Induced Inflammation

Fine dust generated by particulate matter (PM) pollution is a serious ecological issue in industrialized countries and causes disorders of the respiratory system and skin in humans. In the previous study, Sargassum fusiforme was treated with citric acid to remove heavy metals. In this study, the transfer of PM-mediated inflammatory responses through the skin to macrophages was evaluated. Moreover, the anti-adhesive effects of calcium alginate isolated from S. fusiforme (SFCA) against PM-induced inflammation were investigated. The structures of processing and unprocessing SFCA were then analyzed by Fourier-transform infrared spectroscopy (FT-IR), revealing minimal change after acid-processing. SFCA had protective effects both in PM-stimulated HaCaT keratinocytes and RAW 264.7 macrophages. In cellular environments, it was found that SFCA attenuated signal protein expressions such as inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, prostaglandin E₂ (PGE₂), and pro-inflammatory cytokines. Furthermore, macrophages were added to the culture medium of PM-stimulated keratinocytes to induce inflammation. SFCA was observed to significantly inhibit inflammatory responses; additionally, SFCA showed an in vivo anti-adhesive effect in zebrafish embryos.     

Removal of lead from aqueous solutions by Penicillium biomass

The removal of lead ions from aqueous solutions by adsorption on nonliving Penicillium chrysogenum biomass was studied. Biosorption of the Pb(+2) ion was strongly affected by pH. Within a pH range of 4 to 5, the saturated sorption uptake of Pb(+2) was 116 mg/g dry biomass, higher than that of activated charcoal and some other microorganisms. At pH 4.5, P. chrysogenum biomass exhibited selectivity for Pb(+2) over other metal ions such as Cd(+2), Cu(+2), Zn(+2), and As(+3) Sorption preference for metals decreased in the following order: Pb > Cd > Cu > Zn > As. The sorption uptake of Pb(+2) remained unchanged in the presence of Cu(+2) and As(+3), it decreased in the presence of Zn(+2), and increased in the presence of Cd(+2). (c) 1993 John Wiley & Sons, Inc.     

Two models for screening chelating agents for cadmium removal

The effectiveness of some chelating agents to mobilize cadmium from Chinese hamster ovary cells after chronic exposure (20 hr), as well as from cytosolic metallothionein, was studied. In the first protocol, the most effective substance was 2,3-dimercaptopropanol, followed by 2,3-dimercaptopropane-1-sulfonate and 2,3-dimercaptosuccinic acid, whereas CaNa₃3-diethylenetriamine pentaacetic acid × 5H₂O showed less effect. Simultaneous incubation of cells with cadmium and the chelating agent resulted in a different order of effectiveness: CaNa₃ DTPA prevented cadmium uptake almost totally, 2,3-mercaptopropanol by 75% and 2,3-dimercaptopropane-1-sulfonate by 35%. Neither CaNa₃-diethylenetriamine pentaacetic acid × 5H₂O nor 2,3-dimercaptosuccinic acid had altered the distribution of cadmium between the cytosolic protein fractions after a 2 hr incubation of cells, whereas after this period, 2,3-dimercaptopropanol had removed all cadmium from metallothionein, and 2,3-dimercaptopropane-1-sulfonate about 50%. None of the chelating agents had reduced the amount of Cd bound to high molecular weight proteins. In the cell free system, 2,3-dimercaptopropanol and 2,3-dimercaptopropane-1-sulfonate were equally effective and removed all cadmium from metallothionein within ten minutes. CaNa₃-diethylenetriamine pentaacetic acid × 5H₂O, however, even after 60 min, had removed only 50% of the cadmium. The remaining cadmium was found distributed to the high molecular weight and lower molecular weight protein fractions.Abbreviations BAL 2,3-dimercaptopropanol - CHO Chinese hamster ovary cells - DMPS 2,3-dimercaptopropane-1-sulfonate - DMSA 2,3-dimercaptosuccinic acid - DTPA CaNa₃-diethylenetriaminepentaacetic acid × 5 H₂O - HMW proteins high molecular weight proteins - MT metallothionein     

Fabrication of hybrid biosorbent nanoscale zero-valent iron-Sargassum swartzii biocomposite for the removal of crystal violet from aqueous solution

A novel nanoscale zero-valent iron-Sargassum swartzii (nZVI-SS) biocomposite was synthesized and evaluated for its ability to adsorb crystal violet (CV) from aqueous solutions. Involvement of various functional groups of the biosorbent in preferential adsorption of cationic dye was observed using Fourier transform infrared (FTIR) spectroscopy. Morphological changes occurring on the biocomposite materials were characterized using scanning electron microscopy (SEM). Significant increase (～90%) in the biosorption of cationic dye was observed with gradual increase in pH of the medium from 3 to 12. The effect of biosorbent concentration, initial pH, temperature, agitation rate, adsorption time, and initial dye concentration was studied for the biosorption of CV using nZVI biocomposite. During the optimization study, maximum biosorption capacity was observed at pH of 8. At various initial CV concentrations (20–100 mg/L), attainment of batch sorption equilibrium was observed within 120 min of reaction time. The Langmuir isotherm model expressed high coefficient of determination (R² = 0.999). The maximum dye uptake of 200 mg/g was reported at pH 8. Kinetics and temperature profiles were evaluated and reported. Desorption study was carried out with 0.1 M HCl. Investigations proved that nZVI-SS is an excellent biosorbent for the sequestration of CV in aqueous media.     

Biosorption of cadmium,cobalt, nickel,and strontium by aBacillus simplex strain isolated from the vadose zone

A subsurface Gram-positive, endospore-forming, filamentous bacterium, designated ZAN-044, was isolated from a depth of 96.2 m in the vadose zone of the Hanford Site in Washington State. A phylogenetic analysis of the 16S rRNA gene sequence of strain ZAN-044 revealed it to be 99.5% similar toBacillus simplex strain DSM 1321, indicating that they may be members of the same species.B. simplex ZAN-044 was studied along withBacillus subtilis 168, andEscherichia coli K-12 (AB264), two well-characterized metal-sorbing bacteria, for the binding of Cd²⁺, Co²⁺, Ni²⁺, and Sr²⁺. There was rapid (less than 1 h) uptake of 1 M metal by the three bacteria in the order Cd>NiCo>Sr. Binding followed a saturation isotherm at cation concentrations from 0.1 M to 1 mM. Cation binding was pH-dependent, with less binding at low pH.B. simplex ZAN-044 bound more metal thanB. subtilis orE. coli, demonstrating that subsurface microorganisms can remove significant quantities of metals from solution and may be able to influence radionuclide and metal transport in the subsurface.     

Uptake of cadmium ions in white-rot fungus Trametes versicolor: effect of cd (II) ions on the activity of laccase

The effects of cadmium Cd (II) ions on the physiology and biological activity of Trametes versicolor, a strain belonging to white-rotting Basidiomycetes, were examined. Cd (II) ions were added to 10-day-old cultures grown on a liquid medium, or at the time of inoculation. Our experiments showed that T. versicolor is a good cadmium biosorbent from aqueous solution, this strain removing almost all the Cd (ll) ions over the first 2h of incubation by what appears to be a rapid, energy-independent surface binding phenomenon, at the rate of approximately 2mg Cd per g mycelial dry weight. An additional slower and energy-dependent transport mechanism was also present, taking in approximately 0.3mg Cd (II) perg dry weight. It is also shown that these Cd (II) ions significantly stimulate the activity of extracellular laccase when added to 10-day-old cultures.     

Alginate gel biochip for real-time monitoring of intracellular processes in bacterial and yeast cells

A method was developed for producing cell biochips on the basis of calcium alginate. Cell immobilization in microvolumes of nontoxic alginate gel under mild conditions extended the range of testable micro-organisms. The possibility of studying the intracellular processes with alginate gel biochips was demonstrated in model experiments with Escherichia coli, Bordetella bronchiseptica, and Saccharomyces cerevisiae. Cell biochips proved to be suitable for simultaneous monitoring of nucleic acid and protein syntheses with two fluorescent dyes. The effect of chloramphenicol on nucleic acid synthesis was studied with five bacterial strains. Inducible synthesis of the green fluorescence protein (EGFP) in E. coli cells was monitored with the use of biochips. The level of EGFP synthesis correlated with the inductor concentration in the medium.Translated from Molekulyarnaya Biologiya, Vol. 39, No. 1, 2005, pp. 96–102.Original Russian Text Copyright © 2005 by Fesenko, Nasedkina, Chudinov, Prokopenko, Yurasov, Zasedatelev.     

Nutrient translocation from green algal symbionts to the freshwater sponge Ephydatia fluviatilis

The symbiosis between the freshwater sponge Ephydatia fluviatilis and a chlorella-like green alga is not obligate and only occurs when the sponge grows in the light. The algae accumulate intracellular pools of sucrose and glucose and translocate between 9 and 17% of the total photosynthate to the host. The principal product translocated is glucose which is fed directly into the sponge metabolic pool. White sponges transplanted back into the river in the shade grew logarithmically with a mean doubling time of 12 days. Sponges transplanted into illuminated habitats did not grow. It is unknown how the sponge acquires its algal symbiont.     

Separation and preconcentration of copper and cadmium ions from multielemental solutions using Nostoc muscorum-based biosorbents

Nostoc-based biosorbents (AlgaSORBs) useful as chromatographic column-packing materials were prepared by immobilizing cyanobacteria onto solid support in three different fashions: (i) cyanobacterial biofilm (Nostoc-dimethylformamide slurry) over polymer-modified silica gel, (ii) cyanobacterial biofilm over bare silica gel, and (iii) cyanobacteria as such onto polymer-modified silica gel. The materials were characterized for their stabilities and metal sorption/elution conditions under static and dynamic equilibrations. Preconcentrated metals from a test sample were detected following `standard addition' method using a differential pulse anodic stripping voltammetric technique. All sorbents showed 100% affinity for Cd²⁺ ion in a multielemental sample at pH 6.9 and a flow rate of 0.5 ml/min with a preconcentration factor varying between 28- and 75-fold. The first type of AlgaSORB was also found to be selective for Cu²⁺ ion in multielemental analysis at pH 5.2 and a flow rate of 1.0 ml/min with a preconcentration factor of 75. The low capacity and favourable kinetics of these sorbents for Cu²⁺, Cd²⁺, Zn²⁺ and Pb²⁺ ions reflect the suitability of AlgaSORB columns for satisfactory performance in single column ion-chromatography. The polymer spacer between cyanobacterial biofilm and silica gel plays a vital role in holding the immobilized biofilm resulting in better endurance and recyclability for the first type of biosorbent. This revised version was published online in November 2006 with corrections to the Cover Date.     

外源脯氨酸对镉胁迫下小麦幼苗生长的影响

以高蛋白小麦品种“北农9549”为试材,研究喷施不同浓度脯氨酸(0、1.0、5.0和10.0 mmol·L^-1)对镉胁迫下小麦幼苗生长和重金属吸收的影响.结果表明： 以不施镉为对照,1.0 mmol·L^-1CdCl₂胁迫下,小麦幼苗的根长、株高和干质量分别显著下降24.0%、15.0%和27.5%,叶绿素a、b和类胡萝卜素含量分别显著下降23.3%、6.7%和30.8%,超氧化物歧化酶(SOD)活性降低了18.4%,内源脯氨酸、抗坏血酸和丙二醛(MDA)含量分别显著上升78.6%、31.5%和17.9%,细胞膜相对透性显著升高24.8%,过氧化物酶(POD)活性为对照的2.4倍,并且促进对铜的吸收,抑制锌的吸收.随外源脯氨酸浓度的增加,小麦幼苗的根长、株高、干质量、叶绿素和类胡萝卜素含量均逐渐恢复到对照水平,抗坏血酸、内源游离脯氨酸含量和SOD活性均上升,可溶性蛋白含量先上升后下降,POD活性、MDA含量和细胞膜相对透性下降,而锌积累量升高,镉、铜积累量下降.叶面喷施外源脯氨酸可缓解镉对小麦幼苗生长的胁迫,以喷施5.0～10.0 mmol·L^-1外源脯氨酸效果最佳.