Phosphorus amendment competitively prevents chromium uptake and mitigates its toxicity in Spinacea oleracea L.

In this study, we assessed the role of phosphorus in preventing chromium uptake by plants. Two-factor complete randomized pot experiment (5x5 pattern) was conducted hydroponically with Spinacea oleracea L. (spinach), for 28 days in green house. Five concentrations of Cr (2.0, 3.5, 5.0, 6.5 and 8.0 mM), each amended with five concentrations of phosphorus (25, 50, 75, 100 and 125 mM) were supplied. With the phosphorus amendment in the growth medium, accumulation of chromium decreased up to 55% in root and 50% in shoot tissues. A 1.8-fold enhancement in total chlorophyll and 2-fold increase in the biomass of root and shoot were observed due to phosphorus amendment. Levels of superoxide dismutase, catalase, peroxidase and malondialdehyde were reduced by 27, 11.7, 38.1 and 45.5% in root tissues; and 27, 17.4, 32.3 and 35.1%, in shoot tissues, respectively. In conclusion, the phosphorus amendment has been shown not only to moderate the Cr-toxicity in S. oleracea but also enrich chlorophyll content as well as the biomass.

Chromium accumulation potential of Zea mays grown under four different fertilizers.

Chromium (Cr) contamination in soil is a growing concern in sustainable agriculture production and food safety. We performed pot experiment with chromium (30 mg/ soil) to assess the accumulation potential of Zea mays and study the influence of four fertilizers, viz. Farm Yard Manure (FYM), NPK, Panchakavya (PK) and Vermicompost (VC) with respect to Cr accumulation. The oxidative stress and pigment (chlorophyll) levels were also examined. The results showed increased accumulation of chromium in both shoots and roots of Zea mays under FYM and NPK supply, and reduced with PK and VC. While the protein and pigment contents decreased in Cr treated plants, the fertilizers substantiated the loss to overcome the stress. Similarly, accumulation of Cr increased the levels of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) indicating the enhanced damage control activity. However, these levels were relatively low in plants supplemented with fertilizers. Our results confirm that the maize can play an effective role in bioremediation of soils polluted with chromium, particularly in supplementation with fertilizers such as farm yard manure and NPK.

Impact of environmental stress on biochemical parameters of bacteria reducing chromium

Chromium pollution is produced in connection with industrial processes like in tanneries. It has been suggested that bioremediation could be a good option for clean up. The stress effect of variable chromate levels, pHs and growth temperatures on biochemical parameters of two Cr(VI) reducing bacterial strains Pseudomonas aeruginosa Rb-1 and Ochrobactrum intermedium Rb-2 was investigated. Transmission electrone microscopy (TEM) was performed to study the intracellular distribution of Cr(VI). It was observed that initial stress of 1000 µgmL-1 caused significant enhancement of all studied biochemical parameters at pH 7.0 and growth temperature of 37 °C showing great bioremediation potential of the strains. Transmission electron microscopy revealed that the distribution of chromium precipitates was not uniform as they were distributed in the cytoplasm as well as found associated with the periplasm and outer membrane. Fourier transform infrared spectroscopy showed the possible involvement of carboxyl, amino, sulpohonate and hydroxyl groups present on the bacterial cell surface for the binding of Cr(VI) ions. Cr(VI) stress brought about changes in the distridution of these functional groups. It can be concluded that the investigated bacterial strains adjust well to Cr(VI) stress in terms of biochemical parameters and along that exhibited alteration in morphology.

Dynamic Cr(III) uptake by Macrocystis pyrifera and Undaria pinnatifida biomasses

Background: The increased industrial activity has resulted in the discharge of large amount of pollutants including non-degradable metals into the environment. Chromium is produced in several industrial processes and it can be found in the environment in two stable oxidation states, Cr(VI) and Cr(III). Cr(VI) is more hazardous due to its carcinogenic and mutagenic effects on living organisms. Although much less toxic, Cr(III) can also exert genotoxic effects under prolonged or severe exposure. It can be separated from the solution by precipitation but biosorption using brown algae seems to be an effective and sustainable treatment technique owing to its cost-effectiveness and environmental friendly characteristics. Macrocystis pyrifera and Undaria pinnatifida are two marine brown macroalgae with high capability of removing heavy metals including Cr(III) in batch mode of operation. In this work packed bed biosorption of Cr(III) by M. pyrifera and U. pinnatifida biomasses was evaluated. Results: The shapes of the breakthrough curves were rather different for each biomaterial. Parameters like the breakthrough time (t b) andzone mass transfer (MTZ) showed that U. pinnatifida has greater affinity for Cr(III). The maximum adsorption capacity at the exhaustion operating time (t e) demonstrated that M. pyrifera has higher retention capacity of Cr(III). The experimental data were fitted to Thomas, Yoon-Nelson and Dose-Response models. The best correlation coefficient (0.94 or 0.96) was obtained with Dose-Response that accurately describes the uptake behaviour of Cr(III) on the seaweed biomasses under different experimental conditions. The FT-IR spectra evidenced that Cr(III) adsorption occurred mainly by interaction between metal and carboxylate groups present on both the seaweed surfaces. Conclusions: M. pyrifera and U. pinnatifida biomasses are efficient biosorbents for Cr(III) adsorption under a continuous mode of operation although differences between uptake capacities suggest different mechanisms involved in the biosorption.

Physiological behavior of bean (phaseolus vulgaris l.) Seedlings under metal stress

The effects of nickel, cobalt, chromium and zinc on the content of vitamins A, E and C, malondialdehyde (MDA), chlorophyll and carotenoids were investigated in bean seedlings (Phaseolus vulgaris L.) grown in Hoagland solution Control and heavy metal-treated plants were grown for ten days in Hoagland solution. Vitamin A, E, and C content were measured in primary leaves by high performance liquid chromatographic (HPLC). MDA, chlorophyll and carotenoids were measured in leaves by spectrophotometer. In heavy metal treated plants, the levels of MDA, vitamins A, E and C and carotenoids significantly increased, while chlorophyll content decreased in leaves of seedlings. The results indicate that heavy metals caused an oxidative stress in bean plants. The strongest effect on vitamins A, E and C, MDA, chlorophyll and carotenoids was found in plants exposed to nickel, followed by the sequence cobalt > chromium> zinc.

Efecto de la asociación alga-bacteria Bostrychia calliptera (Rhodomelaceae) en el porcentaje de remoción de cromo en laboratorio / The effect of chromium removal by Algae-bacteria Bostrychia calliptera (Rhodomelaceae) consortia under laboratory conditions

Water pollution is one of the most important environmental problems worldwide. Recently, biotechnology studies have oriented efforts to study algae-bacterium consortia with the aim to understand the mechanisms to find a possible solution in environmental sciences. This study determined the percentage of chromium removal by the alga-bacterium association exposed to a set of different chromium concentrations under controlled in vitro conditions. Wild plants of Bostrychia calliptera associated with bacterial populations were collected from Dagua River, Pacific coast of Colombia, and were monitored in the laboratory. The trial was conducted with synthetic seawater in bioreactors at two chromium levels: 5 and 10mg/L, and four different experimental treatments: i) algae-bacteria (AB), ii) algae with antibiotic (AA), iii) algal surface sediment, Natural Bacterial Consortium (CBN), and iv) the control without algae or bacteria. The experimental design followed a model of two factors (chromium concentration x combination types) with repeated measures using one factor. The microbial population behavior and the chromium concentration percentage were monitored by using atomic absorption spectroscopy (AAS). According to the data, Algae-bacteria (AB) treatment was the most efficient combination at 10mg/L (87%), whereas the bacterial consortia (CBN) was the most efficient at 5mg/L (62.85%). The results showed significant differences of chromium uptake between algae-bacteria (AB) and natural bacterial consortia (CBN), meaning the importance of those treatments in the chromium removal from coastal waters.

Para determinar el porcentaje de remoción de cromo en la asociación alga-bacteria, se tomaron ejemplares del alga Bostrychia calliptera de pneumatóforos de Avicennia germinans y Rizophora mangle, en la desembocadura del Río Dagua, Pacífico colombiano. El ensayo se realizó in vitro en agua marina sintética a dos concentraciones de cromo 5 y 10mg/L, empleando biorreactores con cuatro tratamientos; i) material Alga-Bacteria (AB), ii) material algal con antibiótico Alga-antibiótico (AA), iii) consorcio bacteriano natural (CBN) y iv) control sin presencia de B. calliptera ni bacteria. Se monitoreó el comportamiento de poblaciones bacterianas y el porcentaje de disminución de cromo mediante AAS (Espectroscopía de absorción atómica). Se obtuvo diferencias significativas entre los tratamientos Alga-bacteria (AB) y el consorcio bacteriano natural (CBN), siendo Alga-bacteria más eficiente a 10mg/L (87%). El consorcio bacteriano natural CBN obtuvo mayor porcentaje de remoción a bajas concentraciones de cromo a 5ppm (62.85%). Los resultados mostraron una interacción positiva entre las bacterias asociadas (CBN) a la superficie del alga roja B. calliptera en su proceso acumulativo de cromo.

Isolation and characterization of novel potent Cr(VI) reducing alkaliphilic amphibacillus sp. ksuCr3 from hypersaline soda lakes

A strain KSUCr3 with extremely high Cr(VI)-reducing ability under alkaline conditions was isolated from hypersaline soda lakes and identified as Amphibacillus sp. on the basis of 16S rRNA gene sequence analysis. The results showed that Amphibacillus sp. strain KSUCr3 was tolerance to very high Cr(VI) concentration (75 mM) in addition to high tolerance to other heavy metals including Ni2+ (100 mM), Mo2+ (75 mM), Co2+ (5 mM), Mn2+ (100 mM), Zn2+ (2 mM), Cu2+ (2 mM) and Pb (75 mM). Strain KSUCr3 was shown to be of a high efficiency in detoxifying chromate, as it could rapidly reduce 5 mM of Cr(VI) to a non detectable level over 24 hrs. In addition, strain KSUCr3 could reduce Cr(VI) efficiently over a wide range of initial Cr(VI) concentrations (1-10 mM) in alkaline medium under aerobic conditions without significant effect on the bacterial growth. Addition of glucose, NaCl and Na2CO3 to the culture medium caused a dramatic increase in Cr(VI)-reduction by Amphibacillus sp. strain KSUCr3. The maximum chromate removal was exhibited in alkaline medium containing 1.5 percent Na2CO3, 0.8 percent glucose, and 1.2 percent NaCl, at incubation temperature of 40ºC and shaking of 100 rpm. Under optimum Cr(VI) reduction conditions, Cr(VI) reduction rate reached 237 uMh¹ which is one of the highest Cr(VI) reduction rate, under alkaline conditions and high salt concentration, compared to other microorganisms that has been reported so far. Furthermore, the presence of other metals, such as Ni2+, Co2+, Cu2+ and Mn2+ slightly stimulated Cr(VI)-reduction ability by the strain KSUCr3.The isolate, Amphibacillus sp. strain KSUCr3, exhibited an ability to repeatedly reduce hexavalent chromium without any amendment of nutrients, suggesting its potential application in continuous bioremediation of Cr(VI). The results also revealed the possible isolation of potent heavy metals resistant bacteria from extreme environment such as hypersaline soda lakes.

Heavy metal distribution in soil and plant in municipal solid waste compost amended plots

A field study was carried out to evaluate long-term heavy metal accumulation in the top 20 cm of a Tunisian clayey loam soil amended for four consecutive years with municipal solid waste compost at three levels [0, 40 and 80 t/ha/y]. Heavy metals uptake and translocation within wheat plants grown on these soils were also investigated. Compared to untreated soils, compost-amended soils showed significant increases in the content of all measured metals: cadmium, chromium, copper, nickel, lead and zinc in the last three years, especially for plots amended with municipal solid waste compost at 80 t/ha/y. Wheat plants grown on compost-amended soils showed a general increase in metal uptake and translocation, especially for chromium and nickel. This heavy metal uptake was about three folds greater in plots amended at 80 t/ha/y as compared to plots amended at 40 t/ha/y. At the end of the experimental period, the diluting effect resulting from enhanced growth rates of wheat plants due to successive compost applications resulted in lower concentrations in the plants [grain part] grown on treated plots. On the other hand, chromium and nickel were less mobile in the aerial part of wheat plants and were accumulated essentially in root tissues. Plant/soil transfer coefficients for compost-amended treatments were higher than threshold range reported in the literature, indicating that there was an important load/transfer of metal ions from soils to wheat plants

Accumulation of lead, cadmium and chromium in some plants cultivated along the bank of river Ribila at Odo-nla area of Ikorodu, Lagos state, Nigeria.

Heavy metal in soil samples and in washed and unwashed samples of Telfaria occidentalis (ugwu) and Talinum triangulare (waterleaf) cultivated on the bank of river Ribila in Odo-nla village were determined. The soil was moderately polluted with cadmium when compared with Federal Environmental Protection Agency standards. The difference between the unwashed and washed plant samples revealed that metal pollutants exist as superficial contaminants on the foliage surface which is the edible portion and if the foliage portion is washed thoroughly it may be safe for dietary consumption. There is no doubt that continuous discharge of effluent and gaseous emissions from the industries located in this area and dumping of domestic wastes into the river may lead to higher concentrations of these heavy metals in the soil and in the tissue of the leafy vegetables cultivated on the river bank over time. This can eventually lead to pollution of the soil and the cultivated plants, which are ready source of food for the people and other organisms in the food chain.

Biosorption of Ni, Cr and Cd by metal tolerant Aspergillus niger and Penicillium sp. using single and multi-metal solution.

Fungi including Aspergillus and Penicillium, resistant to Ni2+, Cd2+, and Cr6+ were isolated from soil receiving long-term application of municipal wastewater mix with untreated industrial effluents of Aligarh, India. Metal tolerance in term of minimum inhibitory concentration (MIC) was 125-550 microg/ml for Cd, 300-850 microg/ml for Ni and 300-600 microg/ml for Cr against test fungi. Two isolates, Aspergillus niger and Penicillium sp. were tested for their Cr, Ni and Cd biosorption potential using alkali treated, dried and powdered mycelium. Biosorption experiment was conducted in 100 ml of solution at three initial metal concentrations i.e., 2, 4 and 6 mM with contact time (18 hr) and pretreated fungal biomass (0.1g) at 25 degrees C. Biosorption of all metals was found higher at 4 mM initial metal concentration as compared to biosorption at 2 and 6 mM concentrations. At 4 mM initial metal concentration, chromium biosorption was 18.05 and 19.3 mg/g of Aspergillus and Penicillium biomasses, respectively. Similarly, biosorption of Cd and Ni ions was also maximum at 4 mM initial metal concentration by Aspergillus (19.4 mg/g for Cd and 25.05 mg/g of biomass for Ni) and Penicillium (18.6 mg/g for Cd and 17.9 mg/g of biomass for Ni). In general, biosorption of metal was influenced by initial metal concentration and type of the test fungi. The results indicated that fungi of metal contaminated soil have high level of metal tolerance and biosorption properties.

Biosorption of chromium (VI) from aqueous solutions by the husk of Bengal gram (Cicer arientinum)

The potential to remove Cr (VI) from aqueous solutions through biosorption using the husk of Bengal gram (Cicer arientinum), was investigated in batch experiments. The results showed removal of 99.9 percent of chromium in the 10 mgl-1 chromium solution, the biomass required at saturation was 1 g mg-1. Kinetic experiments revealed that the dilute chromium solutions reached equilibrium within 180 min. The biosorptive capacity of the (bgh) was dependent on the pH of the chromium solution, with pH 2 being optimal. The adsorption data fit well with the Langmuir and Freundlich isotherm models. The adsorption capacity calculated from the Langmuir isotherm was 91.64 mg Cr (VI)/g at pH 2. The adsorption capacity increased with increase in agitation speed and an optimum was achieved at 120 rpm. The biosorption of Cr (VI) was studied by Fourier transform infrared spectroscopy (FTIR), which suggested that the presence of Cr (VI) ions in the biomass affects the bands corresponding to hydroxyl and carboxyl groups. Comprehensive characterisation of parameters indicates bgh to be an excellent material for biosorption of Cr (VI) to treat wastewaters containing low concentration of the metal.

Considerações sobre cromo, insulina e exercício físico / Considerations about chromium, insulin and physical exercise

O cromo é um mineral-traço essencial presente em diminutas proporções em alguns alimentos como carnes, cereais integrais, oleaginosas e leguminosas. Atualmente, esse mineral tem sido utilizado como suplemento alimentar no meio esportivo com a proposta de promover maior ganho de massa muscular e maior perda de gordura corporal. Todavia, a participação do cromo no metabolismo resume-se ao aumento da sensibilidade à insulina, por meio da ligação de quatro átomos de cromo a uma proteína intracelular específica denominada apocromodulina, que, por sua vez, liga-se ao receptor de insulina de células de tecidos periféricos concomitantemente à insulina, porém em outro sítio localizado no domínio intracelular. Essa ligação amplifica a cascata de sinais intracelulares responsáveis pelo estímulo da translocação de GLUT4 e, conseqüentemente, aumenta a captação de glicose e aminoácidos. O cromo também inibe a enzima-chave da síntese de colesterol, melhorando o perfil lipídico de indivíduos com dislipidemias. Não são significativas as alterações de composição corporal em esportistas, mas, por outro lado, a suplementação com cromo pode, em alguns casos relatados, melhorar o perfil lipídico e o quadro de diabetes tipo 2 de indivíduos que sofrem destes desequilíbrios metabólicos.

Removal of heavy metal from industrial wastewater using chitosan coated oil palm shell charcoal

This research focuses on understanding biosorption process and developing a cost effective technology for treatment of heavy metals-contaminated industrial wastewater. A new composite biosorbent has been prepared by coating chitosan onto acid treated oil palm shell charcoal (AOPSC). Chitosan loading on the AOPSC support is about 21 percent by weight. The shape of the adsorbent is nearly spherical with particle diameter ranging 100~150 µm. The adsorption capacity of the composite biosorbent was evaluated by measuring the extent of adsorption of chromium metal ions from water under equilibrium conditions at 25ºC. Using Langmuir isotherm model, the equilibrium data yielded the following ultimate capacity values for the coated biosorbent on a per gram basis of chitosan: 154 mg Cr/g. Bioconversion of Cr (VI) to Cr (III) by chitosan was also observed and had been shown previously in other studies using plant tissues and mineral surfaces. After the biosorbent was saturated with the metal ions, the adsorbent was regenerated with 0.1 M sodium hydroxide. Maximum desorption of the metal takes place within 5 bed volumes while complete desorption occurs within 10 bed volumes. Details of preparation of the biosorbent, characterization, and adsorption studies are presented. Dominant sorption mechanisms are ionic interactions and complexation.

Toxicity and accumulation of lead and chromium in Hydrocotyle umbellata.

The aquatic plant, Hydrocotyle umbellata, was studied for its toxicity and accumulation of lead (Pb) and chromium (Cr) in a synthetic solution. Plants were cultured in a modified Hoagland's nutrient solutions supplemented with 20, 40, 60, 80, and 100 mg Pb/l as lead nitrate [Pb(NO3)2] and 2, 4, 6, 8, and 10 mg Cr/l as potassium dichromate (K2Cr2O7). They were separately harvested after 3, 6, 9, and 12 days. Plants exposed to Pb and Cr showed significant decreases in the biomass productivity and total chlorophyll content when the exposure time and metal concentration were increased. The accumulation of Pb and Cr in the plants was significantly increased, but it was not linear with the exposure time and metal concentration. Both metals were accumulated higher in the roots than in the shoots. The bioconcentration factor of Pb was higher than that of Cr at the same exposure time, indicating a higher accumulation potential of Pb than Cr in H. umbellata. Toxicity symptoms of both metals showed a reduction in the production of new plantlets, withering of petioles, and change in color of roots from light green to dark brown. Pb caused leaf chlorosis, whereas Cr caused leaf necrosis. The toxicity symptoms increased when the exposure time and metal concentration were increased.

Scavenging of nickel and chromium toxicity in Aulosira fertilissima by immobilization: effect on nitrogen assimilating enzymes

The ubiquity of heavy metals in the biosphere results in the introduction of high amounts of toxic metals into the food chain from various sources. In the present study, one of the strongest nitrogen fixing cyanobacterium of the rice fields, Aulosira fertilissima, was subjected to nickel and chromium stress and the ameliorating effect of immobilization was investigated. Cell immobilization could protect the organism's growth against the toxicity of both heavy metals at LC50 as compared to lethal concentrations. The nitrate reductase activity in free cells treated with the metals was substantially inhibited but immobilized cells treated with 0.1 ppm nickel was not affected by the metal treatment. Cell immobilization also resulted in a significant protection against sub-lethal concentration of chromium but to a lesser degree than it did with sub- lethal levels of nickel. Control immobilized cells also had higher Nitrogenase activity than control free cells. Nickel and chromium addition markedly decreased the enzyme activity in free cells but immobilized cells exposed to sublethal concentrations of both metals could overcome this decrease. Glutamine synthetase showed similar response under immobilized conditions compared to free cells with both metals. The addition of algal filtrate in 3:1 ratio further increased the nitrogenase activity compared with immobilized cells treated with sublethal doses of both metals. Immobilization facilitated higher uptake of nickel as compared to chromium. The observations of the present study clearly demonstrate the protective effect of immobilization on Aulosira fertilissima against Nickel and chromium toxicity. Rice field ecosystem thus possess a bidirectional natural metal ameliorating system where Aulosira mats act as a naturally immobilized system and the decay of Aulosira along with other cyanobacteria act as natural chelators protecting the rice plants from deleterious effects of the heavy metals. Most importantly is...

Biosorption of heavy metals from waste water using Pseudomonas sp

Biosorption experiments for Cr(VI), Cu(II), Cd(II) and Ni(II) were investigated in this study using nonliving biomass of different Pseudomonas species. The applicability of the Langmuir and Freundlich models for the different biosorbent was tested. The coefficient of determination (R²) of both models were mostly greater than 0.9. In case of Ni(II) and Cu(II), their coefficients were found to be close to one. This indicates that both models adequately describe the experimental data of the biosorption of these metals. The maximum adsorption capacity was found to be the highest for Ni followed by Cd(II), Cu(II) and Cr(VI). Whereas the Freundlich constant k in case of Cd(II) was found to be greater than the other metals. Maximum Cr(VI) removal reached around 38 percent and its removal increased with the increase of Cr(VI) influent. Cu(II) removal was at its maximum value in presence of Cr(VI) as a binary metal, which reached 93 percent of its influent concentration. Concerning to Cd(II) and Ni(II) similar removal ratios were obtained, since it was ranged between 35 to 88 percent and their maximum removal were obtained in the case of individual Cd(II) and Ni(II).

Gut microflora & toxic metals: chromium as a model.

The gastrointestinal tract (GIT) is exposed to various environmental pollutants including metals, that contaminate food and water which may have toxic effects on body. GIT has large amount of microbes that live in symbiosis and help the host in different ways. The resident gut microflora have a significant role to play in detoxification and elimination of the harmful metals from the body. Chromium is a naturally occurring heavy metal found commonly in environment in trivalent (Cr III) and hexavalent (Cr VI) forms. Cr (VI) compounds have been shown to be potent occupational carcinogens. The reduction of Cr (VI) to Cr (III) results in the formation of reactive intermediates that together with oxidative stress and oxidative tissue damage, and a cascade of cellular events including modulation of apoptosis regulatory gene p53 contribute to the cytotoxicity, genotoxicity and carcinogenicity of Cr(VI)-containing compounds. The data discussed here with reference to chromium show that gut microflora have a marked capacity to cope with the increased load of ingested metals and may contribute significantly in the protection against metal toxicity.

Chromium uptake and toxicity effects on growth and metabolic activities in wheat, Triticum aestivum L. cv. UP 2003.

Chromium (Cr) at graded levels when added in sand culture of wheat (T. aestivum L. cv. UP2003) under glasshouse conditions resulted in reduction in biomass, chlorophyll and activities of catalase and peroxidase while enhanced acid phosphatase and ribonuclease activities. Elevated levels of Cr supply significantly reduced the concentration of inorganic phosphorus. With an increase in Cr supply the uptake of chromium also increased significantly in different plant parts especially in roots. Above metabolic lesions due to Cr in wheat provided evidence that the element in nutrient medium if present in excess may be inhibitory to plant growth and development.