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1.
Balk M Weijma J Goorissen HP Ronteltap M Hansen TA Stams AJ 《Applied microbiology and biotechnology》2007,73(5):1203-1211
A sulfate-reducing bacterium, strain WW1, was isolated from a thermophilic bioreactor operated at 65°C with methanol as sole
energy source in the presence of sulfate. Growth of strain WW1 on methanol or acetate was inhibited at a sulfide concentration
of 200 mg l−1, while on H2/CO2, no apparent inhibition occurred up to a concentration of 500 mg l−1. When strain WW1 was co-cultured under the same conditions with the methanol-utilizing, non-sulfate-reducing bacteria, Thermotoga lettingae and Moorella mulderi, both originating from the same bioreactor, growth and sulfide formation were observed up to 430 mg l−1. These results indicated that in the co-cultures, a major part of the electron flow was directed from methanol via H2/CO2 to the reduction of sulfate to sulfide. Besides methanol, acetate, and hydrogen, strain WW1 was also able to use formate,
malate, fumarate, propionate, succinate, butyrate, ethanol, propanol, butanol, isobutanol, with concomitant reduction of sulfate
to sulfide. In the absence of sulfate, strain WW1 grew only on pyruvate and lactate. On the basis of 16S rRNA analysis, strain
WW1 was most closely related to Desulfotomaculum thermocisternum and Desulfotomaculum australicum. However, physiological properties of strain WW1 differed in some aspects from those of the two related bacteria. 相似文献
2.
Chromium(VI) resistance and removal by <Emphasis Type="Italic">Acinetobacter haemolyticus</Emphasis>
Quek Hsiao Pei Shafinaz Shahir A. S. Santhana Raj Zainul Akmar Zakaria Wan Azlina Ahmad 《World journal of microbiology & biotechnology》2009,25(6):1085-1093
The present work highlighted the studies on Cr(VI) reduction by cells of Acinetobacter haemolyticus (A. haemolyticus). The strain tolerated 90 mg Cr(VI) l−1 in LB broth compared to only 30 mg Cr(VI) l−1 in LB agar. From the FTIR analysis, the Cr(III) species formed was also most likely to form complexes with carboxyl, hydroxyl,
and amide groups from the bacteria. A TEM study showed the absence of precipitates on the cell wall region of the bacteria.
Instead, microprecipitates were observed in the cytoplasmic region of the cells, suggesting the transportation of Cr(VI) into
the cells. Intracellular reduction of Cr(VI) was supported by a reductase test using soluble crude cell-free extracts. The
specific reductase activity obtained was 0.52 μg Cr(VI) reduced per mg of protein an hour at pH 7.2 and 37°C. Our results
indicated that A. haemolyticus can be used as a promising microorganism for Cr(VI) reduction from industrial wastewaters. 相似文献
3.
Bacterial consortium-AIE2 with a capability of contemporaneous Cr(VI) reduction and azo dye RV5 decolourization was developed
from industrial wastewaters by enrichment culture technique. The 16S rRNA gene based molecular analyses revealed that the
consortium bacterial community structure consisted of four bacterial strains namely, Alcaligenes sp. DMA, Bacillus sp. DMB, Stenotrophomonas sp. DMS and Enterococcus sp. DME. Cumulative mechanism of Cr(VI) reduction by the consortium was determined using in vitro Cr(VI) reduction assays.
Similarly, the complete degradation of Reactive Violet 5 (RV5) dye was confirmed by FTIR spectroscopic analysis. Consortium-AIE2
exhibited simultaneous bioremediation efficiencies of (97.8 ± 1.4) % and (74.1 ± 1.2) % in treatment of both 50 mg l−1 Cr(VI) and RV5 dye concentrations within 48 h of incubation at pH 7 and 37°C in batch systems. Continuous bioreactor systems
achieved simultaneous bioremediation efficiencies of (98.4 ± 1.5) % and (97.5 ± 1.4) % after the onset of steady-state at
50 mg l−1 input Cr(VI) and 25 mg l−1 input RV5 concentrations, respectively, at medium dilution rate (D) of 0.014 h−1. The 16S rRNA gene copy numbers in the continuous bioreactor as determined by real-time PCR assay indicated that Alcaligenes sp. DMA and Bacillus sp. DMB dominated consortium bacterial community during the active continuous bioremediation process. 相似文献
4.
Production of extracellular polymeric substances from Rhodopseudomonas acidophila in the presence of toxic substances 总被引:2,自引:0,他引:2
A hydrogen-producing photosynthetic bacteria strain, Rhodopseudomonas acidophila, was used to investigate the production of extracellular polymeric substances (EPS) in the presence of toxic substances and the effect of toxicants on bacterial surface characteristics. Addition of the toxic substances including Cu(II), Cr(VI), Cd(II) and 2,4-dichlorophenol (2,4-DCP) stimulated the production of EPS but reduced the cell dry weight. At concentrations of 30 mg l−1 Cu(II), 40 mg l−1 Cr(VI), 5 mg l−1 Cd(II) and 100 mg l−1 2,4-DCP, the EPS content increased by 5.5, 2.5, 4.0 and 1.4 times, respectively, than the control. These toxic substances also greatly influenced the proteins/carbohydrates ratio of EPS. The ratios in the presence of toxic substances were always higher than that of control. Furthermore, under toxic conditions, the increase in the protein content far exceeded than that of others in EPS, suggesting that extracellular proteins could protect cells against toxic substances. The toxic substances significantly changed the surface characteristics and flocculation ability of R. acidophila, such as surface energy, relative hydrophobicity and free energy of adhesion. 相似文献
5.
A novel bacterium, Cr-10, was isolated from a chromium-contaminated site and capable of removing toxic chromium species from
solution by reducing hexavalent chromium to an insoluble precipitate. Sequence analysis of 16S rRNA gene of strain Cr-10 showed
that it was most closely related to Serratia rubidaea JCM 1240T (97.68%). Physiological and chemotaxonomic data also supported that strain Cr-10 was identified as Serratia sp., a genus which was never specially reported chromate-resistant before. Serratia sp., Cr-10 was tolerant to a concentration of 1,500 mg Cr(VI) L−1, which was the highest level reported until now. The optimum pH and temperature for reduction of Cr(VI) by Serratia sp. Cr-10 were found to be 7.0 and 37 °C, respectively. The Cr(VI) reduction was significantly influenced by additional carbon
sources, and among them fructose and lactose offered maximum reduction, with a rate of 0.28 and 0.25 mg Cr(VI) L−1 h−1, respectively. The cell-free extracts and filtrate of the culture were able to reduce Cr(VI) while concentration of total
chromium remained stable in the process, indicating that the enzyme-catalyzed mechanism was applied in Cr(VI) reduction by
the isolate. Additionally, it was found that there was hardly any chromium on the cell surface of the strain, further supporting
that reduction, rather than bioadsorption, plays a major role in the Cr(VI) removal. 相似文献
6.
A continuous flow reactor system was developed to evaluate the efficacy of antimicrobial treatments against sulfate-reducing
bacterial biofilms. An annular reactor operating at a nominal dilution rate of 0.5 h−1 was fed one-tenth strength Postgate C medium diluted in 1.5% NaCl and was inoculated with a mixed culture enriched from oilfield-produced
water on the same medium. Thin biofilms developed in this reactor after 2 days of operation. The activity of these biofilms
resulted in approximately 50 mg S l−1 of sulfide at steady state prior to biocide treatment. Biocide efficacy was quantified by recording the time required for
sulfide production to recover following an antimicrobial treatment. In a control experiment in which pure water was applied,
the time required to reach 10 mg S l−1 sulfide after the treatment was 1.7±1.2 h, whereas the time to reach this level of sulfide after a pulse dose of 500 mg l−1 glutaraldehyde was delayed to 61±11 h. Nitrite treatment suppressed sulfide production as long as the nitrite concentration
remained above 15 mg N l−1. Sulfide production recovered more rapidly after nitrite treatment than it did after glutaraldehyde treatment.
Received 01 February 2002/ Accepted in revised form 13 June 2002 相似文献
7.
Vatsouria A Vainshtein M Kuschk P Wiessner A D K Kaestner M 《Journal of industrial microbiology & biotechnology》2005,32(9):409-414
Industrial wastewater is often polluted by Cr(VI) compounds, presenting a serious environmental problem. This study addresses
the removal of toxic, mutagenic Cr(VI) by means of microbial reduction to Cr(III), which can then be precipitated as oxides
or hydroxides and extracted from the aquatic system. A strain of Staphylococcus epidermidis L-02 was isolated from a bacterial consortium used for the remediation of a chromate-contaminated constructed wetland system.
This strain reduced Cr(VI) by using pyruvate as an electron donor under anaerobic conditions. The aims of the present study
were to investigate the specific rate of Cr(VI) reduction by the strain L-02, the effects of chromate and nitrate (available
as electron acceptors) on the strain, and the interference of chromate and nitrate reduction processes. The presence of Cr(VI)
decreased the growth rate of the bacterium. Chromate and nitrate reduction did not occur under sterile conditions but was
observed during tests with the strain L-02. The presence of nitrate increased both the specific Cr(VI) reduction rate and
the cell number. Under denitrifying conditions, Cr(VI) reduction was not inhibited by nitrite, which was produced during nitrate
reduction. The average specific rate of chromate reduction reached 4.4 μmol Cr 1010 cells−1 h−1, but was only 2.0 μmol Cr 1010 cells−1 h−1 at 20 °C. The maximum specific rate was as high as 8.8–9.8 μmol Cr 1010 cells−1 h−1. The role of nitrate in chromate reduction is discussed. 相似文献
8.
Liping Huang Jingwen Chen Xie Quan Fenglin Yang 《Bioprocess and biosystems engineering》2010,33(8):937-945
Enhancement of Cr (VI) reduction rate and power production from biocathode microbial fuel cells (MFCs) was achieved using
indigenous bacteria from Cr (VI)-contaminated site as inoculum and MFC architecture with a relatively large cathode-specific
surface area of 340–900 m2 m−3. A specific Cr (VI) reduction rate of 2.4 ± 0.2 mg g−1VSS h−1 and a power production of 2.4 ± 0.1 W m−3 at a current density of 6.9 A m−3 were simultaneously achieved at an initial Cr (VI) concentration of 39.2 mg L−1. Initial Cr (VI) concentration and solution conductivity affected Cr (VI) reduction rate, power production and coulombic
efficiency. These findings demonstrate the importance of inoculation and MFC architecture in the enhancement of Cr (VI) reduction
rate and power production. This study is a beneficial attempt to improve the efficiency of biocathode MFCs and provide a good
candidate of bioremediation process for Cr (VI)-contaminated sites. 相似文献
9.
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
10.
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
11.
A Bacillus sp. RE was resistant to chromium and reduced Cr(VI) without accumulating chromium inside the cell. When Cr(VI) was 10 and
40 μg ml−1, >95% of the total Cr(VI) was reduced in 24 and 72 h of growth, respectively, whereas at 80 μg Cr(VI) ml−1 only 50% of Cr(VI) was reduced. However growth was not affected; the cell mass was 0.7–0.8 mg ml−1 in all cases. The cell-free extract showed Cr(VI) reducing enzyme activity which was enhanced (>5 fold) by NADH and NADPH.
Like whole cells the enzyme also reduced Cr(VI) with decreasing efficiency on increasing Cr(VI) concentration. The enzyme
activity was optimal at pH 6.0 and 30 °C. The enzyme was stable up to 30 °C and from pH 5.5 to 8, but from pH 4 to 5 the enzyme
was severely destabilized. Its Km and Vmax were 14 μm and 3.8 nmol min−1 mg−1 respectively. The enzyme activity was enhanced by Cu2+ and Ni2+ and inhibited by Hg2+.
Received 21 September 2005; Revisions requested 5 October 2005; Revisions received 16 November 2005; Accepted 16 November
2005 相似文献
12.
To provide beneficial guide for the application of the magnetic field in the bio-treatment of the Cr(VI)-contained wastewater,
sludge samples from the control bio-system A (absent of magnetic field) and the contrast bio-system B (present of magnetic
field) were used to adsorb the synthetic wastewater with 100 mg l−1 Cr(VI). Influences of two adsorption modes, single adsorption and once continuous adsorption, on the Cr(VI) adsorption capacities
of both sludge samples were compared. And the influence of regeneration on the Cr(VI) adsorption capacities were also studied.
The results of adsorption experiments showed that the Cr(VI) adsorption capacities of the first single adsorption for sludge
sample A and B were pretty nearly, which were 9.79 and 9.93 mg, respectively. And after 5 single adsorption periods, the total
Cr(VI) adsorption capacity and efficiency of the sample B were 25.88 and 55.66 mg Cr(VI) g−1VSS, while those of the control were 14.95 and 33.98 mg Cr(VI) g−1VSS, respectively. For the sludge sample A and B after a single adsorption, both functions of regeneration were remarkable.
But after 13 cycles of the single adsorption-regeneration, the Cr(VI) adsorption capacity and efficiency of the sample B were
110.15 and 189.91 mg Cr(VI) g−1VSS, while those of the control were 70.89 and 140.38 mg Cr(VI) g−1VSS, respectively. Though the Cr(VI) adsorption capacity of a once continuous adsorption period was more than that of a single
adsorption period obviously, the Cr(VI) removal rates of the sludge sample A and B in the third period of once continuous
adsorption-regeneration were only 8.12 and 33.51%, respectively. It was concluded that the weak magnetic field did improve
the Cr(VI) bio-removal efficiency and the sludge stability, the batch treatment was an ideal operation mode for the bio-treatment
of the Cr(VI)-contained wastewater, as compared with the continuous operation mode, but regeneration and enough sludge content
were two necessary conditions to ensure the efficiency of batch treatment. 相似文献
13.
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
14.
Microbial reduction of toxic Cr6+ to the less toxic Cr3+ is potentially a useful bioremediation process. Among the matrices tested for whole cell immobilization of an efficient chromate-reducing
Streptomyces griseus strain, PVA-alginate was the most effective and was used for reduction of Cr(VI) in a bioreactor. Cr6+ reduction efficiency decreased as Cr6+ was increased from 2 to 12 mg l−1 but increased with an increase in biomass concentration. However, increasing the flow rate from 2 to 8 ml h−1 did not significantly affect Cr6+ reduction. The reduction was faster in simulated effluent than in synthetic medium and complete removal of 8 mg Cr6+ l−1 from effluent and synthetic medium occurred in 2 and 12 h, respectively. Our results indicate that immobilized S. griseus cells could be applied for the large-scale bioremediation of chromate-containing effluents and wastewaters. 相似文献
15.
A hexavalent chromium [Cr(VI)] reducing bacterial strain was isolated from chromium-containing slag. It was identified as
Pannonibacter phragmitetus based on physiological, biochemical characteristics and 16S rRNA gene sequence analysis. This bacterium displayed great Cr(VI)
reduction capability. The Cr(VI) could be completely removed in 24 h under anaerobic condition when the initial concentration
was 1,917 mg L−1, with the maximum reduction rate of 562.8 mg L−1 h−1. The Cr(VI) reduction rate increased with the increase of Cr(VI) concentration. P. phragmitetus was able to use many carbon sources such as lactose, fructose, glucose, pyruvate, citrate, formate, lactate, NADPH and NADH
as electron donors, among which the lactate had the greatest power to promote the reduction process. Zn2+, Cd2+ and Ni2+ inhibited, while Cu2+, Pb2+, Mn2+ and Co2+ stimulated the reduction. The optimum pH and temperature for reduction were 9.0 and 30 °C, respectively. The results indicated
that this strain had great potential for application in the bioremediation of chromate-polluted soil and water systems. 相似文献
16.
Yasmin Khambhaty Kalpana Mody Shaik Basha Bhavanath Jha 《World journal of microbiology & biotechnology》2009,25(8):1413-1421
The removal of hexavalent chromium from aqueous solution was studied in batch experiments using dead biomass of three different
species of marine Aspergillus after alkali treatment. All the cultures exhibited potential to remove Cr(VI), out of which, Aspergillus niger was found to be the most promising one. This culture was further studied employing variation in pH, temperature, metal ion
concentration and biomass concentration with a view to understand the effect of these parameters on biosorption of Cr(VI).
Higher biosorption percentage was evidenced at lower initial concentration of Cr(VI) ion, while the sorption capacity of the
biomass increased with rising concentration of ions. Biomass as low as 0.8 g l−1 could biosorb 95% Cr(VI) ions within 2,880 min from an aqueous solution of 400 mg l−1 Cr(VI) concentration. Optimum pH and temperature for Cr(VI) biosorption were 2.0 and 50°C, respectively. Kinetic studies
based on pseudo second order models like Sobkowsk and Czerwinski, Ritchie, Blanchard and Ho and Mckay rate expressions have
also been carried out. The nature of the possible cell–metal ion interactions was evaluated by FTIR, SEM and EDAX analysis. 相似文献
17.
A novel system combining acoustic wave impedance (AWI) analyzer with UV-vis spectrophotometer was developed for the study
of chromium (VI) reduction kinetics by Pseudomonas aeruginosa. AWI gave information about the growth of Pseudomonas aeruginosa, and UV-vis spectrophotometer gave information about the concentration of chromium (VI) simultaneously. A combined system
response model, for chromium (VI) reduction kinetics at lower initial chromium (VI) concentrations, was derived and proved
based on the novel system. Taking into account the effect of bacterial growth on chromium (VI) reduction, the new model successfully
simulated chromium (VI) bioremediation process. By fitting chromium (VI) reduction data toward the derived model, the kinetic
parameters related to the process were obtained. When the concentration of peptone was 10 g L−1, the half-velocity reduction rate constant K
C and the maximum specific chromium (VI) reduction rate constant νmax were 0.7682 mg chromium (VI) L−1 and 2.5814 × 10−12 mg chromium (VI) cells−1 h−1, respectively. It was found that the combined system can provide real-time, reliable, and two-dimensional kinetic information,
and can be applied to study other biological processes. 相似文献
18.
Yongxue Yang Guofeng Liu Manzhu Bao 《In vitro cellular & developmental biology. Plant》2006,42(6):520-524
Summary A protocol of somatic embryogenesis and plant regeneration from petiole segments of Parthenocissus tricuspidata Planch. has been developed. Embryogenic tissue was induced on B5 (Gamborg) basal medium supplemented with 2.25–9.0 μM 2,4-dichlorophenoxyacetic acid, 500 mg l−1 casein hydrolysate (CH), and 0.1 gl−1 activated charcoal. Somatic embryos were induced on B5 medium containing various concentrations of benzyladenine (BA) (4.44,
6.66, and 8.88 μM) and α-naphthaleneacetic acid (NAA) (0, 0.54, and 1.61 μM) plus 500 mg l−1 CH. Ninety percent of normal somatic embryos were converted into plantlets directly on Murashige and Skoog (MS) medium free
of plant growth regulators. Shoots could be induced from abnormal somatic embryos on MS medium containing 4.44 μM BA, 0.05 μM NAA, and 500 mg l−1 CH. Genotypic differences were found in the process of somatic embryogenesis and plant regeneration. Histological analysis
confirmed the process of somatic embryogenesis. Regenerated plantlets with well-developed roots were successfully acclimatized
in greenhouse and all plants showed normal morphological characteristics. 相似文献
19.
Wenyan Wang Chenggang Wang Bang-Lian Huang Bangquan Huang 《Plant Cell, Tissue and Organ Culture》2008,92(2):165-171
A protocol was developed for regeneration and Agrobacterium-mediated genetic transformation of Lesquerella fendleri. Calli were first induced from hypocotyls and cotyledons on MS plus 0.5 mg l−1 BA, 1 mg l−1 NAA and 1 mg l−1 2,4-D, then co-cultivated for 2–3 days in darkness on MS supplemented with 0.5 mg l−1 BA, 0.2 mg l−1 NAA and 100 μmol l−1As together with Agrobacterium tumefaciens strain EHA105/pCAMBIA1301 that harbored genes for uidA (GUS) and hygromycin resistance. Following co-cultivation, calli transfected by A. tumefaciens were transferred to MS with 0.5 mg l−1 BA, 0.2 mg l−1NAA, 500 mg l−1 Cef and 10 mg l−1 hygromycin and cultured for 10 days, then the hygromycin was increased to 20 mg l−1 on the same medium. After 4 weeks the resistant regenerants were transferred to MS with 0.5 mg l−1BA, 0.2 mg l−1 NAA, 500 mg l−1 Cef and 25 mg l−1 hygromycin for further selections. Transgenic plants were confirmed by polymerase chain reaction analysis, GUS histochemical
assay and genomic Southern blot hybridization. With this approach, the average regeneration frequency from transfected calli
was 22.70%, and the number of regenerated shoots per callus was 6–13. Overall results described in this study demonstrate
that Agrobacterium-mediated transformation is a promising approach for improvement of this Lesquerella species. 相似文献
20.
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