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Chromium(VI) removal and its association with exopolysaccharide (EPS) production in cyanobacteria were investigated. Synechocystis sp. BASO670 produced higher EPS (548 mg L−1) than Synechocystis sp. BASO672 (356 mg L−1). While the EC50 of the Cr(VI) for Synechocystis sp. BASO670 and Synechocystis sp. BASO672 were determined as 11.5 mg L−1, and 2.0 mg L−1, respectively, there was no relation between Cr(VI) removal and EPS production. Synechocystis sp. BASO672, which has higher EPS value, removed (33%) more Cr(VI) than Synechocystis sp. BASO670. Monomer compositions of EPS of each of the isolates were determined differently. Synechocystis sp. BASO672 which removed higher Cr(VI), had higher values of uronic acid and glucuronic acid (192 μg/mg and 89%, respectively). Our results showed that EPS might play a role in Cr(VI) tolerance. Monomer composition, especially uronic acid and glucuronic acid content of EPS may have enhanced Cr(VI) removal. 相似文献
3.
BackgroundChromium (Cr) is a naturally-occurring element that is used in various fields of industry. Humans may be exposed to hexavalent chromium [Cr(VI)], which is one of the stable valence states of the chromium through contaminated soil, air, and water. Exposure to Cr(VI) through contaminated drinking water, soil and air causes various cancers and also fertility problems in animals and humans. Quercetin (QCT), a common flavonoid compound, has numerous biological effects as an antioxidant and free radical scavenger, but its function and mechanisms in reproductive processes in various species remain unclear. This study aims to determine the chromium effects on mice oocyte quality and the ameliorative effect of QCT in both in vitro and in vivo experimental models.MethodsFor the in vitro experiment, oocytes were collected and divided into the control, sham, QCT-treated, Cr(VI) (potassium dichromate), and treatment [Cr(VI)+QCT] groups. Collected oocytes were cultured in maturation medium with or without 10 µM quercetin and 10 µM Cr(VI) for 14 h based on the defined experimental design. For the in vivo experiment, the mice were randomly divided into the control, sham, QCT-treated, Cr(VI), and Cr(VI) + QCT groups. Control and sham mice received regular drinking water and diet. Cr(VI) group received Cr(VI) (50 ppm in drinking water) and Cr(VI) + QCT group received 50 ppm Cr(VI) with QCT (20 mg/kg body wt, through i.p) for a period of 21 days and then oocytes were collected and cultured for 14 h for in vitro maturation. For both experiments, at the end of the culture period, we examined the ameliorative effect of QCT on oocyte maturation, spindle formation, ROS production, mitochondrial function, and apoptosis.ResultsOur in vitro and in vivo results showed that Cr(VI) disrupt the oocyte maturation and spindle formation (P < 0.001). Furthermore, we found that exposure to Cr(VI) significantly increased ROS levels and decreased mitochondrial membrane potential (P < 0.001). In addition, exposure to Cr(VI) induced early apoptosis and downregulated the Bcl-2 mRNA expression and upregulated the Caspase-3 and Bax mRNAs expression (P < 0.01). Finally, quercetin significantly restored the detrimental effects of Cr(VI).ConclusionThe results indicated that quercetin protects the oocytes against Cr(VI) toxicity through the suppression of oxidative stress and apoptosis. The conclusions drawn from our study's findings suggest that quercetin might be useful agent for oocyte maturation in case of possible exposure to toxic substances such as chromium. 相似文献
4.
Bio-reduction of Cr(VI) by exopolysaccharides (EPS) from indigenous bacterial species of Sukinda chromite mine, India 总被引:1,自引:0,他引:1
Chrome mining activity has contributed intensively towards pollution of hexavalent chromium around Sukinda Valley, Orissa, India. In an attempt to study the specific contribution of exopolysaccharides (EPS) extracted from indigenous isolates towards Cr(VI) reduction, three chromium (VI) tolerant strains were isolated from the effluent mining sludge. Based on the tolerance towards Cr(VI) and EPS production capacity, one of them was selected for further work. The taxonomic identity of the selected strain was confirmed to be Enterobacter cloacae (showing 98% similarity in BLAST search to E. cloacae) through 16S rRNA analysis. The EPS production was observed to increase with increasing Cr(VI) concentration in the growth medium, highest being 0.078 at 100?mg/l Cr(VI). The extracted EPS from Enterobacter cloacae SUKCr1D was able to reduce 31.7% of Cr(VI) at 10?mg/l concentration, which was relevant to the prevailing natural concentrations at Sukinda mine effluent sludge. The FT-IR spectral studies confirmed the surface chemical interactions of hexavalent chromium with EPS. 相似文献
5.
The capacity of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans to reduce different concentrations of hexavalent chromium in shake flask cultures has been investigated. A. ferrooxidans reduces 100% of chromium (VI) at concentrations of 1, 2.5 and 5 ppm, but in the presence of 10 ppm only 42.9% of chromium
(VI) was reduced after 11 days of incubation. A. thiooxidans showed a lower capacity to reduce this ion and total reduction of chromium (VI) was only obtained for concentrations of 1
and 2.5 ppm, whereas 64.7% and 30.5% was reached for 5 and 10 ppm, respectively, after 11 days. A continuous flow mode system
was subsequently investigated, in which A. thiooxidans was immobilized on elemental sulphur and the acidic medium obtained was employed to solubilize chromium (III) and to reduce
chromium (VI) present in a real electroplating waste [30% of chromium (III) and 0.1% of chromium (VI)]. The system enabled
the reduction of 92.7% of hexavalent chromium and represents a promising way to treat this type of waste in the industry. 相似文献
6.
Hexavalent chromium reduction and accumulation by Acinetobacter AB1 isolated from Fez tanneries effluents were tested. The effects of some environmental factors such as pH, temperature,
and exposure time on Cr(VI) reduction and resistance were investigated. We found that this strain was able to resist to concentrations
as high as 400 mg/l of Cr(VI). Moreover, pH 10 and the temperature 30°C constitute favourable conditions to the growth and
reduction of Acinetobacter AB1. Complete reduction of Cr(VI) was observed at low initial Cr(VI) concentrations of 50 mg/l after 72 h of incubation.
Furthermore, Transmission electron microscope (TEM) analysis showed morphological changes in AB1 strain due 48H exposure to
100 mg/l chromate concentration and revealed circular electron dense (dark black point) inclusion within the cell cytoplasm
suggesting chromium deposition within the cells. 相似文献
7.
R S Baker A M Bonin A Arlauskas R K Tandon P T Crisp J Ellis 《Mutation research》1984,138(2-3):127-132
After treatment with potassium chromate at concentrations causing ultramicroscopic cellular lesions, a significant proportion (up to 75%) of TA100 colonies fail to replicate on fresh minimal plates containing biotin. This suggests that chromium(VI) may not always induce his- reversion to his+ in Salmonella TA100. The terms 'false' or phenotypic reversion have been used to distinguish such instances from 'true' or genotypic reversion, where progeny his+ cells readily grow on biotin replica plates. Results of the present study indicate that the majority of chromate-exposed colonies, initially scored as his-, are identifiable as his+ after 24 h culture on nutrient agar. Moreover, chromate exerts a cytostatic effect on TA100 since early colony development is suppressed at high chromate concentrations. A gradual chemical reduction of chromium(VI) ions by normal media compounds is probably responsible for the re-emergence of colony growth during prolonged incubation of test plates. Thus, temporary growth inhibition at high chromate concentration appears to be responsible for most of the non-replicating colonies detected in mutagenicity assays of chromium(VI). 相似文献
8.
Clothilde Bertin Corinne Pau-Roblot Josiane Courtois Lucía Manso-Silván Fran?ois Thiaucourt Florence Tardy Dominique Le Grand Fran?ois Poumarat Patrice Gaurivaud 《PloS one》2013,8(7)
Contagious bovine pleuropneumonia is a severe respiratory disease of cattle that is caused by a bacterium of the Mycoplasma genus, namely Mycoplasma mycoides subsp. mycoides (Mmm). In the absence of classical virulence determinants, the pathogenicity of Mmm is thought to rely on intrinsic metabolic functions and specific components of the outer cell surface. One of these latter, the capsular polysaccharide galactan has been notably demonstrated to play a role in Mmm persistence and dissemination. The free exopolysaccharides (EPS), also produced by Mmm and shown to circulate in the blood stream of infected cattle, have received little attention so far. Indeed, their characterization has been hindered by the presence of polysaccharide contaminants in the complex mycoplasma culture medium. In this study, we developed a method to produce large quantities of EPS by transfer of mycoplasma cells from their complex broth to a chemically defined medium and subsequent purification. NMR analyses revealed that the purified, free EPS had an identical β(1−>6)-galactofuranosyl structure to that of capsular galactan. We then analyzed intraclonal Mmm variants that produce opaque/translucent colonies on agar. First, we demonstrated that colony opacity was related to the production of a capsule, as observed by electron microscopy. We then compared the EPS extracts and showed that the non-capsulated, translucent colony variants produced higher amounts of free EPS than the capsulated, opaque colony variants. This phenotypic variation was associated with an antigenic variation of a specific glucose phosphotransferase permease. Finally, we conducted in silico analyses of candidate polysaccharide biosynthetic pathways in order to decipher the potential link between glucose phosphotransferase permease activity and attachment/release of galactan. The co-existence of variants producing alternative forms of galactan (capsular versus free extracellular galactan) and associated with an antigenic switch constitutes a finely tuned mechanism that may be involved in virulence. 相似文献
9.
Aravindhan R Sreeram KJ Rao JR Nair BU 《The Journal of General and Applied Microbiology》2007,53(2):71-79
The contamination of soil and wastewaters with Cr(VI) is a major problem. It has been suggested that microbial methods for Cr(VI) reduction are better than chemical methods, as they do not add other ions or toxic chemicals to the environment. In this study an aerobic reduction of Cr(VI) to Cr(III) by employing mixed Pseudomonas cultures isolated from a marshy land has been reported. The role of chromium concentration, temperature, pH and additives on the microbial reduction of Cr(VI) has been investigated. NADH was found to enhance the rate of reduction of Cr(VI). Complete reduction of chromium(VI) has been possible even at chromium(VI) concentrations of 300 ppm. Ions like SO(4)(2-) and poly-phenols inhibited the metabolic activity relating to Cr(VI) reduction. Under optimal conditions 100 mg/L of Cr(VI) was completely reduced within 180 min. 相似文献
10.
Wenjie Zhu Zhihui Yang Zemin Ma Liyuan Chai 《World journal of microbiology & biotechnology》2008,24(7):991-996
In recent years, more and more attentions are put on the remediation of Cr(VI) contamination with chromate resistant bacteria.
Leucobacter sp. CRB1 was a novel chromate reducing bacteria isolated from the soil of chromite ore processing residue (COPR) disposal
site in Changsha, China. The objectives of this study were to evaluate the Cr(VI) tolerance of Leucobacter sp. CRB1 as well as its tolerant mechanism, and Cr(VI) reduction ability. The results showed that Leucobacter sp. CRB1 was able to tolerate 4,000 mg/l of hexavalent chromium with 34.5% reduction efficiency. At the optimum pH 9.0, the
maximum concentration of chromate be reduced completely was 1,818 mg/l in growing cells and 2,100 mg/l in resting cells. Scanning
electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) showed that extracellular Cr(VI) reduction of Leucobacter sp. CRB1 contributed to its high tolerance and high reduction ability. With repeating spiking, 2,490 mg/l hexavalent chromium
was reduced totally within 17 h. The results suggest Leucobacter sp. CRB1 has potential application for remediation of high concentration of Cr(VI) contamination. 相似文献
11.
de María Guillén-Jiménez F Morales-Barrera L Morales-Jiménez J Hernández-Rodríguez CH Cristiani-Urbina E 《Journal of industrial microbiology & biotechnology》2008,35(11):1277-1287
The main aim of this study was to investigate the influence of the sulfate ion on the tolerance to Cr(VI) and the Cr(VI) reduction
in a yeast strain isolated from tannery wastewater and identified as Candida sp. FGSFEP by the D1/D2 domain sequence of the 26S rRNA gene. The Candida sp. FGSFEP strain was grown in culture media with sulfate concentrations ranging from 0 to 23.92 mM, in absence and presence
of Cr(VI) [1.7 and 3.3 mM]. In absence of Cr(VI), the yeast specific growth rate was practically the same in every sulfate
concentration tested, which suggests that sulfate had no stimulating or inhibiting effect on the yeast cell growth. In contrast,
at the two initial Cr(VI) concentrations assayed, the specific growth rate of Candida sp. FGSFEP rose when sulfate concentration increased. Likewise, the greater efficiencies and volumetric rates of Cr(VI) reduction
exhibited by Candida sp. FGSFEP were obtained at high sulfate concentrations. Yeast was capable of reducing 100% of 1.7 mM Cr(VI) and 84% of 3.3 mM
Cr(VI), with rates of 0.98 and 0.44 mg Cr(VI)/L h, with 10 and 23.92 mM sulfate concentrations, respectively. These results
indicate that sulfate plays an important role in the tolerance to Cr(VI) and Cr(VI) reduction in Candida sp. FGSFEP. These findings may have significant implications in the biological treatment of Cr(VI)-laden wastewaters. 相似文献
12.
Evaluation of the bioremoval of Cr(VI) and TOC in biofilters under continuous operation using response surface methodology 总被引:1,自引:0,他引:1
In the present study, the bioremoval of Cr(VI) and the removal of total organic carbon (TOC) were achieved with a system composed
by an anaerobic filter and a submerged biofilter with intermittent aeration using a mixed culture of microorganisms originating
from contaminated sludge. In the aforementioned biofilters, the concentrations of chromium, carbon, and nitrogen were optimized
according to response surface methodology. The initial concentration of Cr(VI) was 137.35 mg l−1, and a bioremoval of 85.23% was attained. The optimal conditions for the removal of TOC were 4 to 8 g l−1 of sodium acetate, >0.8 g l−1 of ammonium chloride and 60 to 100 mg l−1 of Cr(VI). The results revealed that ammonium chloride had the strongest effect on the TOC removal, and 120 mg l−1 of Cr(VI) could be removed after 156 h of operation. Moreover, 100% of the Cr(VI) and the total chromium content of the aerobic
reactor output were removed, and TOC removals of 80 and 87% were attained after operating the anaerobic and aerobic reactors
for 130 and 142 h, respectively. The concentrations of cells in both reactors remained nearly constant over time. The residence
time distribution was obtained to evaluate the flow through the bioreactors. 相似文献
13.
Okeke BC 《Journal of industrial microbiology & biotechnology》2008,35(12):1571-1579
Pollution of terrestrial surfaces and aquatic systems by hexavalent chromium, Cr(VI), is a worldwide public health problem.
A chromium resistant bacterial isolate identified as Exiguobacterium sp. GS1 by 16S rRNA gene sequencing displayed high rate of removal of Cr(VI) from water. Exiguobacterium sp. GS1 is 99% identical to Exiguobacterium acetylicum. The isolate significantly removed Cr(VI) at both high and low concentrations (1–200 μg mL−1) within 12 h. The Michaelis–Menten K
m
and V
max for Cr(VI) bioremoval were calculated to be 141.92 μg mL−1 and 13.22 μg mL−1 h−1, respectively. Growth of Exiguobacterium sp. GS1 was indifferent at 1–75 μg mL−1 Cr(VI) in 12 h. At initial concentration of 8,000 μg L−1, Exiguobacterium sp. GS1 displayed rapid bioremoval of Cr(VI) with over 50% bioremoval in 3 h and 91% bioremoval in 8 h. Kinetic analysis
of Cr(VI) bioremoval rate revealed zero-order in 8 h. Exiguobacterium sp. GS1 grew and significantly reduced Cr(VI) in cultures containing 1–9% salt indicating high salt tolerance. Similarly
the isolate substantially reduced Cr(VI) over a wide range of temperature (18–45 °C) and initial pH (6.0–9.0). The T
opt and initial pHopt were 35–40 °C and 7–8, respectively. Exiguobacterium sp. GS1 displayed a great potential for bioremediation of Cr(VI) in diverse complex environments. 相似文献
14.
Alberto J. Martín-Rodríguez Katia Villion Secil Yilmaz-Turan Francisco Vilaplana Åsa Sjöling Ute Römling 《Microbial biotechnology》2021,14(3):1183-1200
Bacterial colony morphology can reflect different physiological stages such as virulence or biofilm formation. In this work we used transposon mutagenesis to identify genes that alter colony morphology and cause differential Congo Red (CR) and Brilliant Blue G (BBG) binding in Shewanella algae, a marine indigenous bacterium and occasional human pathogen. Microscopic analysis of colonies formed by the wild-type strain S. algae CECT 5071 and three transposon integration mutants representing the diversity of colony morphotypes showed production of biofilm extracellular polymeric substances (EPS) and distinctive morphological alterations. Electrophoretic and chemical analyses of extracted EPS showed differential patterns between strains, although the targets of CR and BBG binding remain to be identified. Galactose and galactosamine were the preponderant sugars in the colony biofilm EPS of S. algae. Surface-associated biofilm formation of transposon integration mutants was not directly correlated with a distinct colony morphotype. The hybrid sensor histidine kinase BarA abrogated surface-associated biofilm formation. Ectopic expression of the kinase and mutants in the phosphorelay cascade partially recovered biofilm formation. Altogether, this work provides the basic analysis to subsequently address the complex and intertwined networks regulating colony morphology and biofilm formation in this poorly understood species. 相似文献
15.
A previous study has shown that Vibrio alginolyticus ZJ-51 undergoes colony phase variation between opaque/rugose (Op) and translucent/smooth (Tr). The AI-2 quorum-sensing master regulator ValR, a homolog to V. harveyi LuxR, was suggested to be involved in the transition. To investigate the role of ValR in the variation and in biofilm formation, an in-frame deletion of valR in both Op and Tr backgrounds was carried out. The mutants in both backgrounds showed an intermediate colony morphotype, where the colonies were less opaque/rugose but not fully translucent/smooth either. They also showed an intermediate level of motility. However, biofilm formation was severely decreased in both mutants and polar flagella were depleted also. Quantitative PCR showed that most of the genes related to flagellar and polysaccharide biosynthesis were upregulated in the mutant of Op background (ΔvalR/Op) but downregulated in the mutant of Tr background (ΔvalR/Tr) compared with their parental wild-type strains. This suggests that ValR may control biofilm formation by regulating flagellar biosynthesis and affect the expression of the genes involved in colony phase variation in V. alginolyticus. 相似文献
16.
《Enzyme and microbial technology》2005,36(5-6):700-705
The mixed cultures has been isolated from industrial saline wastewater contaminated with chromium(VI), using enrichment in the presence of 50 mg l−1 chromium(VI) and 4% (w/v) NaCl at pH 8. In this study, the molasses (M) medium was selected a suitable medium for the effective chromium bioaccumulation by the mixed cultures. Eleven pure isolates obtained from mixed cultures and some of them showed high bioaccumulation in the M media containing about 100 mg l−1 chromium(VI) and 4% NaCl. The strain 8 (99.3%) and 10 (99.1%) were able to bioaccumulate more efficient than the mixed culture (98.9%) in this media. But the highest specific Cr uptake was obtained by the mixed cultures followed by strain 8 and 10 with 56.71, 33.14 and 21.7 mg g−1, respectively. Bioaccumulation of chromium(VI) ions by the strain 8 growing in the media with chromium(VI) and NaCl was studied in a batch system as a function of initial chromium(VI) (86.6–547.6 mg l−1) and NaCl (0, 2, 4, 6% w/v) concentrations. During all the experiments, the uptake yield of the strain 8 was highly affected from NaCl concentrations in the medium at high initial chromium(VI) concentrations. But at low chromium(VI) concentration, strain 8 was not affected from NaCl concentrations in the medium. The maximum uptake yield were obtained in the M media with 2% NaCl as 98.8% for 110.0 mg l−1, 98.6% for 217.1 mg l−1, 98.6% for 381.7 mg l−1 and 98.2% for 547.6 mg l−1 initial chromium(VI) concentrations. The strain 8 tolerated a 6% (w/v) NaCl concentration was able to bioaccumulate more than 95% of the applied chromium(VI) at the 97.6–224.4 mg l−1 initial chromium(VI) concentrations. The results presented in this paper was shown that these pure and mixed cultures might be of use for the bioaccumulation of chromium(VI) from saline wastewater. 相似文献
17.
Marta A. Polti Mariana C. AtjiánMaría J. Amoroso Carlos M. Abate 《International biodeterioration & biodegradation》2011,65(8):1175-1181
The aim of this work was to evaluate a strategy to reduce the bioavailable chromium fraction in soil, using a Cr(VI) resistant microorganism, Streptomyces sp. MC1, under non sterile conditions, with maize plants as bioindicator and/or bioremediator.Soil samples were contaminated with 100, 200 and 400 mg kg−1 of Cr(VI) or Cr(III). Bioavailable chromium (35%) was only detected in samples with Cr(VI). Soil samples with Cr(VI) 200 mg kg−1 were inoculated with Streptomyces sp. MC1, and bioavailable chromium decreased up to 73%.Zea mays seedlings were planted in soil samples contaminated with chromium. Plantlets accumulated chromium mainly as Cr(III), and biomass decreased up to 88%. Streptomyces sp. MC1 was inoculated in soil samples contaminated with 200 mg kg−1 of Cr(VI) and Z.mays seedlings were planted.Streptomyces sp. MC1 caused Z.mays biomass increase (57%), chromium accumulation and bioavailable chromium decreased up to 46% and 96%, respectively.This work constitutes the first contribution of cooperative action between actinobacteria and Z.mays in the bioremediation of Cr(VI) contaminated soil. The large removal capacity of bioavailable chromium by Streptomyces sp. MC1 and Z.mays infers that they could be successfully applied together in bioremediation of soils contaminated with Cr(VI). 相似文献
18.
Jinxia Yang Minyan He Gejiao Wang 《World journal of microbiology & biotechnology》2009,25(9):1579-1587
Chromate-reducing microorganisms with the ability of reducing toxic chromate [Cr(VI)] into insoluble trivalent chromium [Cr(III)]
are very useful in treatment of Cr(VI)-contaminated water. In this study, a novel chromate-reducing bacterium was isolated
from Mn/Cr-contaminated soil. Based on morphological, physiological/biochemical characteristics and 16S rRNA gene sequence
analyses, this strain was identified as Intrasporangium sp. strain Q5-1. This bacterium has high Cr(VI) resistance with a MIC of 17 mmol l−1 and is able to reduce Cr(VI) aerobically. The best condition of Cr(VI) reduction for Q5-1 is pH 8.0 at 37°C. Strain Q5-1
is also able to reduce Cr(VI) in resting (non-growth) conditions using a variety of carbon sources as well as in the absence
of a carbon source. Acetate (1 mmol l−1) is the most efficient carbon source for stimulating Cr(VI) reduction. In order to apply strain Q5-1 to remove Cr(VI) from
wastewater, the bacterial cells were immobilized with different matrices. Q5-1 cells embedded with compounding beads containing
4% PVA, 3% sodium alginate, 1.5% active carbon and 3% diatomite showed a similar Cr(VI) reduction rates to that of free cells.
In addition, the immobilized Q5-1 cells have the advantages over free cells in being more stable, easier to re-use and minimal
clogging in continuous systems. This study provides potential applications of a novel immobilized chromate-reducing bacterium
for Cr(VI) bioremediation. 相似文献
19.
Summary A tropical white-rot basidiomycete, BDT-14 (DSM 15396) was investigated for its chromium (VI) biosorption potential from an
aqueous solution. Pre-treatment of fungal biomass with acid resulted in 100% metal adsorption compared to only 26.64% adsorption
without any pre-treatment. Chromium adsorption was a rapid process at early exposure resulting in 60% chromium removal within
the first 2 h of exposure. An increase in biomass showed an increase in the total metal ions adsorption but a decrease in
specific uptake of metal ions. The concentrations of chromium had a pronounced effect on the rate of adsorption. The adsorption
efficiency was 100% when the initial Cr (VI) concentration was 100 mg l−1 with 1,000 mg biomass. Only 47.5% adsorption was observed with 500 mg l−1 Cr (VI) concentration. The adsorption data fit well with the Langmuir and Freundlich isotherm models. Comprehensive characterization
of parameters indicates BDT−14 biomass as a promising material for Cr (VI) adsorption. 相似文献
20.
Maximizing EPS production from Pseudomonas aeruginosa and its application in Cr and Ni sequestration
Heavy metal contamination of water bodies has been a cause of grave concern around the globe. Analysis of various industrial effluents has revealed a perilous level of Cr (VI) and Ni (II). Pseudomonas aeruginosa is an extracellular polymeric substances (EPSs) producing bacterium. EPS has a great potential in the sequestration of heavy metal ions. In the present study efforts have been made to understand the effect of time, pH, and temperature on production of EPS by P. aeruginosa (MTCC 1688). The extracted EPS has been applied for removal of Ni (II) and Cr (VI) ions from aqueous system. The results revealed that highest EPS yield (26 mg/50 mL) can be obtained after 96 h of incubation at pH 6 and 32 °C temperature in 50 mL of culture. Treatment of 10 mg/L Cr (VI) and Ni (II) with 30 mg/L EPS resulted in the removal of 26% and 9% of Cr (VI) and Ni (II), respectively. Fourier-transform infrared spectral analysis revealed the involvement of –OH, –NH, C–O, diketone, and ester functional groups of EPS in the attachment of Cr (VI) ion while involvement of amide and –CO groups in Ni (II) binding with EPS. Scaling-up the production of EPS using bioreactor may further help in developing an efficient process for treatment of water polluted with Cr and Ni. 相似文献