Biosorption Performance of Multimetal Resistant Fungus Penicillium chrysogenum XJ-1 for Removal of Cu2+ and Cr6+ from Aqueous Solutions

Adsorption for heavy metals via biomaterials such as fungal biomass presents a practical remediation technique for polluted water. Among all known filamentous fungi, Penicillium chrysogenum is widespread in nature and can serve as a biosorbent for heavy metals. In the current study, the ability of P. chrysogenum XJ-1 to remove copper (Cu²⁺) and chromium (Cr⁶⁺) from water was evaluated. The maximum biosorption capacity of XJ-1 for Cu²⁺ reached 42.83 ± 0.57 mg g^?1 dry biomass at pH 5.0 after the equilibrium time of 1.5 h. The maximum biosorption capacity for Cr⁶⁺ at pH 3.0 reached 52.69 ± 1.68 mg g^?1 dry biomass after the equilibrium time of 1.5 h. The biosorption data of XJ-1 biomass were well fitted to the Freundlich isotherm model and the pseudo-second-order Lagergren kinetic model. Laundry powder-treated and HCl-treated XJ-1 biomass significantly enhanced its adsorption capacity to Cu²⁺ and Cr⁶⁺, respectively. HCl and NaOH were suitable desorbents for Cu²⁺/Cr⁶⁺ loading biomass, respectively. Fourier transform infrared spectroscopy analyses revealed that hydroxyl, amine, and sulfonyl groups on the biosorbent contributed to binding Cu²⁺ and Cr⁶⁺ and that carbonyl and carboxyl groups were also vital binding sites of Cu²⁺. Scanning electron microscopy and energy-dispersive x-ray (SEM-EDX) analyses confirmed that considerable amounts of metals were precipitated on the cell surface of XJ-1. Our results suggested that XJ-1 might be used to purify multimetal-contaminated water. This low-cost and eco-friendly biomass of XJ-1 seems to have a broad use in the restoration of metal-contaminated water.     

Hyperhalophilic archaeal biofilms: growth kinetics,structure, and antagonistic interaction in continuous culture

Biofilms by the hyperhalophilic archaea Halorubrum sp. and Halobacterium sp. were analyzed, and for the first time the progression of structural features and the developmental parameters of these sessile populations are described. Optical slicing and digital analysis of sequential micrographs showed that their three dimensional structure was microorganism dependent. Biofilms of Halobacterium sp. developed in clusters that covered about 30% of the supporting surface at the interface level and expanded over about 86?±?4 μm in thickness, while Halorubrum sp. biofilms covered less than 20% of the surface and reached a thickness of 41?±?1 μm. The kinetics of growth was lower in biofilms, with generation times of 27?±?1 and 36?±?2 h for Halobacterium sp. and Halorubrum sp., respectively, as compared to 8.4?±?0.3 and 14?±?1 h in planktonic cultures. Differences between microorganisms were also observed at the cell morphology level. The interaction between the two microorganisms was also evaluated, showing that Halobacterium sp. can outcompete already established Halorubrum sp. biofilms by a mechanism that might include the combined action of tunnelling swimmers and antimicrobial compounds.     

Feasibility of Typha Latifolia for High Salinity Effluent Treatment in Constructed Wetlands for Integration in Resource Management Systems

High salinity wastewaters have limited treatment options due to the occurrence of salt inhibition in conventional biological treatments. Using recirculating marine aquaculture effluents as a case study, this work explored the use of Constructed Wetlands as a treatment option for nutrient and salt loads reduction. Three different substrates were tested for nutrient adsorption, of which expanded clay performed better. This substrate adsorbed 0.31 mg kg^?1 of NH₄ ⁺?N and 5.60 mg kg^?1 of PO₄ ^3??P and 6.9 mg kg^?1 dissolved salts after 7 days of contact. Microcosms with Typha latifolia planted in expanded clay and irrigated with aquaculture wastewater (salinity 2.4%, 7 days hydraulic retention time, for 4 weeks), were able to remove 94% NH₄ ⁺?N (inlet 0.25 ± 0.13 mg L^?1), 78% NO₂ ^??N (inlet 0.78 ± 0.62 mg L^?1), 46% NO₃ ^??N (inlet 18.83 ± 8.93 mg L^?1) whereas PO₄ ^3??P was not detected (inlet 1.41 ± 0.21 mg L^?1). Maximum salinity reductions of 52% were observed. Despite some growth inhibition, plants remained viable, with 94% survival rate. Daily treatment dynamics studies revealed rapid PO₄ ^3??P adsorption, unbalancing the N:P ratio and possibly affecting plant development. An integrated treatment approach, coupled with biomass valorization, is suggested to provide optimal resource management possibilities.     

Fatty acid composition and biological activities of Isochrysis galbana T-ISO,Tetraselmis sp. and Scenedesmus sp.: possible application in the pharmaceutical and functional food industries

Organic and water extracts of Isochrysis galbana T-ISO (=Tisochrysis lutea), Tetraselmis sp. and Scenedesmus sp. were evaluated for their antioxidant activity, acetylcholinesterase (AChE) inhibition, cytotoxicity against tumour cell lines, and fatty acids and total phenolic content (TPC). I. galbana T-ISO had the highest TPC (3.18 mg GAE g^?1) and radical scavenging activity, with an IC₅₀ value of 1.9 mg mL^?1 on the acetone extract. The extracts exhibited a higher ability to chelate Fe²⁺ than Cu²⁺, and the maximum Fe²⁺ chelating capacity was observed in the hexane extract of Scenedesmus sp. (IC₅₀=0.73 mg mL^?1) and Scenedesmus sp. (IC₅₀?=?0.73 mg mL^?1). The highest ability to inhibit AChE was observed in the water and ether extracts of Scenedesmus sp., with IC₅₀ values of 0.11 and 0.15 mg mL^?1, respectively, and in the water extract of I. galbana (IC₅₀?=?0.16 mg mL^?1). The acetone extract of I. galbana T-ISO significantly reduced the viability of human hepatic carcinoma HepG2 cells (IC₅₀?=?81.3 μg mL^?1) as compared to the non-tumour murine stromal S17 cell line, and displayed a selectivity index of 3.1 at the highest concentration tested (125 μg mL^?1). All species presented a highly unsaturated fatty acids profile. Results suggest that these microalgae, particularly I. galbana T-ISO, could be a source of biomolecules for the pharmaceutical industry and the production of functional food ingredients and can be considered as an advantageous alternative to several currently produced microalgae.     

Modeling of Pb(II) adsorption by a fixed-bed column

Removal of Pb(II) from an aqueous environment using biosorbents is a cost-effective and environmentally benign method. The biosorption process, however, is little understood for biosorbents prepared from plant materials. In this study, the biosorption process was investigated by evaluating four adsorption models. A fixed-bed column was prepared using a biosorbent prepared from the aquatic plant Hydrilla verticillata. The effect of bed height and flow rate on the biosorption process was investigated. The objective of the study was to determine the ability of H. verticillata to biosorb Pb(II) from an aqueous environment and to understand the process, through modeling, to provide a basis to develop a practical biosorbent column. Experimental breakthrough curves for biosorption of 50 mg L^?1 aqueous Pb(II) using a fixed-bed column with 1.00 cm inner diameter were fitted to the Thomas, Adams-Bohart, Belter, and bed depth service time (BDST) models to investigate the behavior of each model according to the adsorption system and thus understand the adsorption mechanism. Model parameters were evaluated using linear and nonlinear regression methods. The biosorbent removed 65% (82.39 mg g^?1 of biosorbent) of Pb(II) from an aqueous solution of Pb(NO₃)₂ at a flow rate of 5.0 ml min^?1 in a 10 cm column. Na₂CO₃ was used to recover the adsorbed Pb(II) ions as PbCO₃ from the biosorbent. The Pb(II) was completely desorbed at a bed height of 10.0 cm and a flow rate of 5.0 ml min^?1. Fourier transform infrared (FT-IR) analysis of the native biosorbent and Pb(II)-loaded biosorbent indicated that the hydroxyl groups and carboxylic acid groups were involved in the metal bonding process. The FT-IR spectrum of Pb(II)-desorbed biosorbent showed an intermediate peak shift, indicating that Pb(II) ions were replaced by Na⁺ ions through an ion-exchange process. Of the four models tested, the Thomas and BDST models showed good agreement with experimental data. The calculated bed sorption capacity N₀ and rate constant k_a were 31.7 g L^?1 and 13.6 × 10^?4 L mg^?1 min^?1 for the C_t/C₀ value of 0.02. The BDST model can be used to estimate the column parameters to design a large-scale column.     

Biosorption of Heavy Metals (Cd2+, Cu2+, Co2+, and Mn2+) by Thermophilic Bacteria,Geobacillus thermantarcticus and Anoxybacillus amylolyticus: Equilibrium and Kinetic Studies

ABSTRACT

Two strains of thermophilic bacteria, Geobacillus thermantarcticus and Anoxybacillus amylolyticus, were employed to investigate the biosorption of heavy metals including Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ ions. The effects of different biosorption parameters such as pH (2.0–10.0), initial metal concentrations (10.0–300.0 mg L^?1), amount of biomass (0.25–10 g L^?1), temperature (30–80°C), and contact time (15–120 min) were investigated. Concentrations of metal ions were determined by using an inductively coupled plasma optical emission spectrometry (ICP-OES). Optimum pHs for Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ biosorption by Geobacillus thermantarcticus were found to be 4.0, 4.0, 5.0, and 6.0, respectively. For Anoxybacillus amylolyticus, the optimum pHs for Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ biosorption were found to be 5.0, 4.0, 5.0, and 6.0, respectively. The Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ removals at 50 mg L^?1 in 60 min by 50 mg dried cells of Geobacillus thermantarcticus were 85.4%, 46.3%, 43.6%, and 65.1%, respectively, whereas 74.1%, 39.8%, 35.1%, and 36.6%, respectively, for Anoxybacillus amylolyticus. The optimum temperatures for heavy metal biosorption were near the optimum growth temperatures for both strains. Scatchard plot analysis was employed to obtain more compact information about the interaction between metal ions and biosorbents. The plot results were further studied to determine if they fit Langmuir and Freundlich models.     

Alleviation of metal and BTEX inhibition on BTEX degradation using PVA-immobilized degrader: kinetic model of BTEX degradation

Alleviation of metal inhibition on BTEX degradation using PVA-immobilized degrader (Mycobacterium sp. CHXY119) was investigated. When BTEX of 29 mg L^?1 [B:T:E:X = 1:1:1:1 (mg)] was used, more than 99 % of BTEX was simultaneously degraded by the free cells within 170 h. In contrast, BTEX of 114–172 mg L^?1 seriously inhibited degradation. High concentrations of metals (Mn²⁺: 15, Ni²⁺: 10, and Zn²⁺: 10 mg L^?1) also strongly inhibited BTEX degradation by the free cells at BTEX of 29 mg L^?1. Immobilization of degraders alleviated the inhibition of BTEX and heavy metals at high concentrations. A modified non-competitive inhibition model well described the BTEX degradation by the free and immobilized cells in the absence and presence of metal ions (R ² = 0.92–0.99). The above results provide valuable information on treatment of metal-BTEX co-contaminated wastewater by the immobilized degrader.     

Optimization of arylacetonitrilase production from Alcaligenes sp. MTCC 10675 and its application in mandelic acid synthesis

Alcaligenes sp. MTCC 10675 has been isolated from soil sample using enrichment method and has nitrilase catalytic system which is highly specific for the hydrolysis of arylaliphatic nitriles. Optimization of culture conditions using response surface methodology and inducer-mediated approach enhanced arylacetonitrilase production significantly (2.4-fold). Isobutyronitrile acted as an effective inducer for the induction of arylacetonitrilase, and it is highly specific for arylacetonitriles (phenyl acetonitrile and mandelonitrile). Arylacetonitrilase has no effect on its relative velocity (V _r) up to 20 mM substrate (mandelonitrile) concentration and at 30 mM mandelonitrile, 23.4 % degree of inhibition (I _d) was recorded. Half life of arylacetonitrilase of Alcaligenes sp. MTCC 10675 was 27.5 h at 25 °C. Hg²⁺, Ag⁺, Pb³⁺, and Co²⁺ were strong inhibitor of arylacetonitrilase activity which resulted into 100 %, 91 %, 84 %, and 83 % inhibition, respectively. Polar protic solvent (dichloromethane, dimethylsulphooxide, and n-butanol) reduce arylacetonitrilase activity up to 80–94 % at 10 % concentration. Alcaligenes sp. MTCC 10675 has higher biocatalytic activity, i.e., 3.9 gg^-1 dcw, which is highest in comparison to till reported organism. Arylacetonitrilase-mediated hydrolysis of racemic mandelonitrile resulted into R-(-) mandelic acid with 99.0 % enantiomeric excess (e.e.)     

Production of versatile peroxidase from Pleurotus eryngii by solid-state fermentation using agricultural residues and evaluation of its catalytic properties

Interest in production of ligninolytic enzymes has been growing over recent years for their use in various applications such as recalcitrant pollutants bioremediation; specifically, versatile peroxidase (VP) presents a great potential due to its catalytic versatility. The proper selection of the fermentation mode and the culture medium should be an imperative to ensure a successful production by an economic and available medium that favors the process viability. VP was produced by solid-state fermentation (SSF) of Pleurotus eryngii, using the agricultural residue banana peel as growth medium; an enzymatic activity of 10,800 U L^?1 (36 U g^?1 of substrate) was detected after 18 days, whereas only 1800 U L^?1 was reached by conventional submerged fermentation (SF) with glucose-based medium. The kinetic parameters were determined by evaluating the H₂O₂ and Mn²⁺ concentration effects on the Mn³⁺-tartrate complex formation. The results indicated that although the H₂O₂ inhibitory effect was observed for the enzyme produced by both media, the reaction rates for VP obtained by SSF were less impacted. This outcome suggests the presence of substances released from banana peel during the fermentation, which might exhibit a protective effect resulting in an improved kinetic behavior of the enzyme.     

Inorganic carbon and pH effect on growth and lipid productivity of Tetraselmis suecica and Chlorella sp (Chlorophyta) grown outdoors in bag photobioreactors

There has been considerable interest in cultivation of green microalgae (Chlorophyta) as a source of lipid that can alternatively be converted to biodiesel. However, almost all mass cultures of algae are carbon-limited. Therefore, to reach a high biomass and oil productivities, the ideal selected microalgae will most likely need a source of inorganic carbon. Here, growth and lipid productivities of Tetraselmis suecica CS-187 and Chlorella sp were tested under various ranges of pH and different sources of inorganic carbon (untreated flue gas from coal-fired power plant, pure industrial CO₂, pH-adjusted using HCl and sodium bicarbonate). Biomass and lipid productivities were highest at pH 7.5 (320?±?29.9 mg biomass L^?1 day^?1and 92?±?13.1 mg lipid L^?1 day^?1) and pH 7 (407?±?5.5 mg biomass L^?1 day^?1 and 99?±?17.2 mg lipid L^?1 day^?1) for T. suecica CS-187 and Chlorella sp, respectively. In general, biomass and lipid productivities were pH 7.5?>?pH 7?>?pH 8?>?pH 6.5 and pH 7?>?pH 7.5?=?pH 8?>?pH 6.5?>?pH 6?>?pH 5.5 for T. suecica CS-187 and Chlorella sp, respectively. The effect of various inorganic carbon on growth and productivities of T. suecica (regulated at pH?=?7.5) and Chlorella sp (regulated at pH?=?7) grown in bag photobioreactors was also examined outdoor at the International Power Hazelwood, Gippsland, Victoria, Australia. The highest biomass and lipid productivities of T. suecica (51.45?±?2.67 mg biomass L^?1 day^?1 and 14.8?±?2.46 mg lipid L^?1 day^?1) and Chlorella sp (60.00?±?2.4 mg biomass L^?1 day^?1 and 13.70?±?1.35 mg lipid L^?1 day^?1) were achieved when grown using CO₂ as inorganic carbon source. No significant differences were found between CO₂ and flue gas biomass and lipid productivities. While grown using CO₂ and flue gas, biomass productivities were 10, 13 and 18 %, and 7, 14 and 19 % higher than NaHCO₃, HCl and unregulated pH for T. suecica and Chlorella sp, respectively. Addition of inorganic carbon increased specific growth rate and lipid content but reduced biomass yield and cell weight of T. suecica. Addition of inorganic carbon increased yield but did not change specific growth rate, cell weight or content of the cell weight of Chlorella sp. Both strains showed significantly higher maximum quantum yield (F_v/F_m) when grown under optimum pH.     

Measurement of net ecosystem exchange,productivity and respiration in three spruce forests in Sweden shows unexpectedly large soil carbon losses

Measurement of net ecosystem exchange was made using the eddy covariance method above three forests along a north-south climatic gradient in Sweden: Flakaliden in the north, Knottåsen in central and Asa in south Sweden. Data were obtained for 2 years at Flakaliden and Knottåsen and for one year at Asa. The net fluxes (N_ep) were separated into their main components, total ecosystem respiration (R_t) and gross primary productivity (P_g). The maximum half-hourly net uptake during the heart of the growing season was highest in the southernmost site with ?0.787 mg CO₂ m^?2 s^?1 followed by Knottåsen with ?0.631 mg CO₂ m^?2 s^?1 and Flakaliden with ?0.429 mg CO₂ m^?2 s^?1. The maximum respiration rates during the summer were highest in Knottåsen with 0.245 mg CO₂ m^?2 s^?1 while it was similar at the two other sites with 0.183 mg CO₂ m^?2 s^?1. The annual N_ep ranged between uptake of ?304 g C m^?2 year^?1 (Asa) and emission of 84 g C m^?2 year^?1 (Knottåsen). The annual R_t and P_g ranged between 793 to 1253 g C m^?2 year^?1 and ?875 to ?1317 g C m^?2 year^?1, respectively. Biomass increment measurements in the footprint area of the towers in combination with the measured net ecosystem productivity were used to estimate the changes in soil carbon and it was found that the soils were losing on average 96–125 g C m^?2 year^?1. The most plausible explanation for these losses was that the studied years were much warmer than normal causing larger respiratory losses. The comparison of net primary productivity and P_g showed that ca 60% of P_g was utilized for autotrophic respiration.     

First Thermostable Endo-β-1,4-Glucanase from Newly Isolated Xanthomonas sp. EC102

A novel gene encoding thermostable endoglucanase was identified in Xanthomonas sp. EC102 from soil. The gene had 1,458 base pairs of open reading frame, which encode a 52-kDa protein of 486 amino acid residues. Sequence of the amino acid residues was similar with the endoglucanase from Xanthomonas campestris pv. campestris ATCC33913 (GenBank Accession No. NP_638867.1) (94 % identity). The endoglucanase was overexpressed in Escherichia coli BL21 and purified. Temperature for the highest enzymatic activity was 70 °C and pH optima was pH 5.5. The specific activity of the endoglucanase toward carboxymethylcellulose (CMC) was approximately 2 μmol min^?1 mg^?1, V _max for CMC was 1.44 μmol mg^?1 min^?1, and K _m values was 25.6 mg mL^?1. The EC102 endoglucanase was stable at temperatures up to 60 °C, and it was activated by 0.1 mM of Mn²⁺ and Co²⁺. This is the first report about thermostable endoglucanase from Xanthomonas sp.     

A Study on Cadmium Phytoremediation Potential of Indian Mustard,Brassica juncea

The objective of this study was to investigate Cd phytoremediation ability of Indian mustard, Brassica juncea. The study was conducted with 25, 50, 100, 200 and 400 mg Kg^?1 CdCl₂ in laboratory for 21 days and Cd concentrations in the root, shoot and leaf tissues were estimated by atomic absorption spectroscopy. The plant showed high Cd tolerance of up to 400 mg Kg^?1 but there was a general trend of decline in the root and shoot length, tissue biomass, leaf chlorophyll and carotenoid contents. The tolerance index (TI) of plants were calculated taking both root and shoot lengths as variables. The maximum tolerance (TI _shoot = 87.4 % and TI _root = 89.6 %) to Cd toxicity was observed at 25 mg Kg^?1, which progressively decreased with increase in dose. The highest shoot (10791 μg g^?1 dry wt) and root (9602 μg g^?1 dry wt) Cd accumulation was achieved at 200 mg kg^?1 Cd treatment and the maximum leaf Cd accumulation was 10071.6 μg g^?1 dry wt achieved at 100 mg Kg^?1 Cd, after 21 days of treatment. The enrichment coefficient and root to shoot translocation factor were calculated, which, pointed towards the suitability of Indian mustard for removing Cd from soil.     

An isobutyronitrile-induced bienzymatic system of Alcaligenes sp. MTCC 10674 and its application in the synthesis of α-hydroxyisobutyric acid

Alcaligenes sp. MTCC 10674 was isolated as acetone cyanohydrin hydrolyzing bacterium from soil of orchid gardens of Himachal Pradesh. Acetone cyanohydrin hydrolyzing activity of this organism comprised nitrile hydratase and amidase activities. It exhibited higher substrate specificity towards aliphatic hydroxynitrile (acetone cyanohydrin) in comparison to arylaliphatic hydroxynitrile. Isobutyronitrile (40 mM) acted as a carbon source as well as inducer for growth of Alcaligenes sp. MTCC 10674 and expression of acetone cyanohydrin hydrolyzing activity. Optimization of culture condition using response surface methodology increased acetone cyanohydrin hydrolyzing activity by 1.3-fold, while inducer mediation approach increased the activity by 1.2-fold. The half life of this enzyme was 25 h at 15 °C. V _max and K _m value for acetone cyanohydrin hydrolyzing enzyme was 0.71 μmol mg^?1 min^?1 and 14.3 mM, when acetone cyanohydrin was used as substrate. Acetone cyanohydrin hydrolyzing enzyme encountered product inhibition and IC50 and K _i value were calculated to be 28 and 10.2 mM, respectively, when product α-hydroxyisobutyric acid was added in the reaction. Under optimized reaction conditions at 40 ml fed batch scale, 3 mg dcw ml ^? resting cells of Alcaligenes sp. MTCC 10674 fully converted 0.33 M acetone cyanohydrin into α-hydroxyisobutyric acid (1.02 g) in 6 h 40 min. The characterization of acetone cyanohydrins hydrolyzing activity revealed that it comprises bienzymatic nitrile hydrolyzing system, i.e. nitrile hydratase and amidase for the production of α-hydroxyisobutyric acid from acetone cyanohydrin and maximum 70 % yield is being reported for the first time.     

Interactive biosorption by microalgal biomass as a tool for fluoride removal

Maximum biosorption of Ca²⁺ was at 50 mg Ca²⁺ l^–1 with both Anabaena fertilissima (2.8 mg Ca²⁺ g^–1 dry wt) and Chlorococcum humicola (4.4 mg g^–1). Such Ca²⁺-treated biomasses, accumulated, respectively, 7 mg F g^–1 DW from an aqueous solution of 10 mg F l^–1 and 4.5 mg F g^–1 DW from 15 mg F l^–1. Data for both Ca²⁺ and F^– biosorption fitted the Langmuir adsorption isotherm indicating monolayer adsorption at a constant energy.     

Phytofiltration of As3+, As5+, and Hg by the aquatic macrophyte Potamogeton pusillus L,and its potential use in the treatment of wastewater

The aim of this paper was to investigate the capacity of the aquatic macrophyte Potamogeton pusillus to remove As³⁺, As⁵⁺, and Hg from aqueous solutions. The plants were exposed to 0 mg.L^?1, 0.1 mg.L^?1, 0.5 mg.L^?1, 1 mg.L^?1, or 2 mg.L^?1 of As³⁺, As⁵⁺, and Hg for 20 days. The results obtained for the individual removal of As³⁺, As⁵⁺, and Hg from water solutions, together with their accumulation in P. pusillus, indicate that this plant can be effectively used for the removal of Hg and of moderate concentrations of As³⁺ or As⁵⁺ (0.1 mg.L^?1) from aquatic systems. Roots and leaves accumulated the highest amount of As when the plant was exposed to As⁵⁺, but when it was exposed to As³⁺, the root accumulated the highest amount of As, and the leaves, the highest amount of Hg. When compared to other aquatic plants species, the results showed that P. pusillus demonstrated a higher Hg accumulation (2465 ± 293 µg.g^?1) when the transfer coefficient was 40,580 ± 3762 L.kg ^?1, showing the great potential of this macrophyte for phytoremediation of water contaminated with Hg. To the extent of our knowledge, this is the first report on bioaccumulation of As³⁺, As⁵⁺, and Hg by P. pusillus.     

Enhanced phytoremediation of cadmium and/or benzo(a)pyrene contaminated soil by hyperaccumlator Solanum nigrum L.

The role of same amendment on phytoremediating different level contaminated soils is seldom known. Soil pot culture experiment was used to compare the strengthening roles of cysteine (CY), EDTA, salicylic acid (Sa), and Tween 80 (TW) on hyperaccumulator Solanum nigrum L. phytoremediating higher level of single cadmium (Cd) or Benzo(a)pyrene (BAP) and their co-contaminated soils. Results showed that the Cd capacities (ug pot^?1) in shoots of S. nigrum in the combined treatment T_{0.1EDTA+0.9CY} were the highest for the 5 and 15 mg kg^?1 Cd contaminated soils. When S. nigrum remediating co-contaminated soils with higher levels of Cd and BAP, that is, 5 mg kg^?1 Cd + 1 mg kg^?1 BAP and 15 mg kg^?1 Cd + 2 mg kg^?1 BAP, the treatment T_{0.9CY+0.9Sa+0.3TW} showed the best enhancing remediation role. This results were different with co-contaminated soil with 0.771 mg kg^?1 Cd + 0.024 mg kg^?1 BAP. These results may tell us that the combine used of CY, SA, and TW were more useful for the contaminated soils with higher level of Cd and/or BAP. In the combined treatments of Sa+TW, CY was better than EDTA.     

Effects of low pH and Pb2+ stress on living cyanobacterium, Phormidium angustissimum West & G.S.West : A test of its feasibility as a living biosorbent

Pb²⁺ adsorption by the living cyanobacterium, Phormidium angustissimum followed the Langmuir adsorption model, with the maximum adsorption capacity (q _max ) of 295.4?±?13.8 mg g^?1. This result suggests that P. angustissimum is a promising living biosorbent to remove Pb²⁺ from wastewaters. Living biosorbents are better able to remove Pb²⁺ from wastewater than dead biosorbents, however there are practical limitations for their use are encountered in extreme conditions such as low pH and high Pb²⁺ concentration. The feasibility of using cyanobacterium, P. angustissimum, as a living biosorbent for the extraction of Pb²⁺ from wastewater was studied by investigating its photosynthestic performance and tolerance under Pb²⁺ (0–5 mg ?L^?1) contamination and low pH (pH?3–7). Decreased photosynthetic performance caused by Pb²⁺ contamination and low pH stress was detected in this study by means of a reduction of the maximum photochemical efficiency of PSII (F_v/F_m). Detoxification mechanisms of P. angustissimum on Pb²⁺ appeared to increase its intracellular polysaccharides (IPS), exocellular polysaccharides (EPS), and protein. Living P. angustissimum could increase the pH of the solution which resulted in Pb²⁺ precipitation. The unique ability of P. angustissimum to remove Pb²⁺ and to grow under toxic conditions, demonstrated herein, indicates that it is a promising living biosorbent for mildly acidic water contaminated with Pb²⁺ in bioremoval systems in the which pH is not lower than 5 and Pb²⁺ is not higher than 5 mg L^?1.     

Purification and biochemical characterization of a new alkali-stable laccase from Trametes sp. isolated in Tunisia: role of the enzyme in olive mill waste water treatment

A white-rot basidiomycete, isolated from decayed acacia wood (from Northwest of Tunisia) and identified as Trametes sp, was selected in a broad plate screening because of its ability to decolorize and dephenolize olive oil mill wastewater (OMW) efficiently. The major laccase was purified and characterized as a monomeric protein with apparent molecular mass of 61 kDa (SDS-PAGE). It exhibits high enzyme activity over broad pH and temperature ranges with optimum activity at pH 4.0 and a temperature of 60 °C. The purified laccase is stable at alkaline pH values. The enzyme retained 50 % of its activity after 90 min of incubation at 55 °C. Using ABTS, this laccase presented K _m and V _max values of 0.05 mM and 212.73 μmoL min^?1 mg^?1, respectively. It has shown a degrading activity towards a variety of phenolic compounds. The purified laccase was partially inhibited by Fe²⁺, Zn²⁺, Cd²⁺ and Mn²⁺, while Cu²⁺ acted as inducer. EDTA (10 mM) and NaN₃ (10 mM) were found to completely inhibit its activity. 73 % OMW was dephenolized after 315 min incubation at 30 °C with 2 U mL^?1 of laccase and 2 mM HBT.     

226Ra, 238U and Cd adsorption kinetics and binding capacity of two cyanobacterial strains isolated from highly radioactive springs and optimal conditions for maximal removal effects in contaminated water

Biomass-based decontamination methods are among the most interesting water treatment techniques. In this study, 2 cyanobacterial strains, Nostoc punctiforme A.S/S4 and Chroococcidiopsis thermalis S.M/S9, isolated from hot springs containing high concentrations of radium (²²⁶Ra), were studied to be associated with removal of radionuclides (²³⁸U and ²²⁶Ra) and heavy metal cadmium (Cd) from aqueous solutions. The adsorption equilibrium data was described by Langmuir and Freundlich isotherm models. Kinetic studies indicated that the sorption of 3 metals followed pseudo-second-order kinetics. Effects of biomass concentration, pH, contact time, and initial metal concentration on adsorption were also investigated. Fourier-transform infrared spectroscopy revealed active binding sites on the cyanobacterial biomass. The obtained maximum biosorption capacities were 630 mg g^?1 and 37 kBq g^?1 for ²³⁸U and ²²⁶Ra for N. punctiforme and 730 mg g^?1 and 55 kBq g^?1 for C. thermalis. These 2 strains showed maximum binding capacity 160 and 225 mg g^?1, respectively for Cd adsorption. These results suggest that radioactivity resistant cyanobacteria could be employed as an efficient adsorbent for decontamination of multi-component, radioactive and industrial wastewater.