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1.
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
2.
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
3.
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
4.
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
5.
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
6.
Anaerobic bacteria that reduce hexavalent chromium [Cr(VI)] to trivalent [Cr(III)] are common in soils and were used to develop
a bioprocess employing a selection strategy. Indigenous Cr(VI)-reducers were enriched from Cr(VI)-contaminated soil under
anaerobic conditions. The mixed culture was then tested for Cr(VI)-reducing activity in a chemostat, followed by transfer
to a 1-L packed-bed bioreactor operated at 30°C for additional study. The support material used in the reactor consisted
of 6-mm porcelain saddles. Cr(VI) concentrations in the liquid ranged from 140–750 mg L−1. Cr(VI)-reducing bacteria were the dominant population with Cr(VI)-reduction rates of approximately 0.71 mg g−1 dry cells h−1 achieved at Cr(VI) concentrations of 750 mg L−1. These results indicate a potential for selecting and maintaining indigenous Cr(VI)-reducers in a bioreactor for Cr(VI)-remediation
of groundwater or soil wash effluents.
Received 09 January 1996/ Accepted in revised form 15 November 1996 相似文献
7.
The salinity tolerances of four species of small fishes native to the Murray-Darling river system were measured. Slow acclimation
LD50s were 43.7 ± 1.7 g L−1 for Craterocephalus stercusmuscarum Gunther, 38.0 ± 1.1 g L−1 for Hypseleotris klunzingeri (Ogilby), 58.7 ± 0.9 g L−1 for Retropinna semoni (Weber), and 29.8 ± 0.7 g L−1 for Melanotaenia splendida (Castelnau). The salinity tolerance of M. splendida was also measured by direct transfer, providing an estimated LD50 (infinite exposure time) of 20.8 g L−1, ∼ 70% of the slow acclimation value. Results suggest that at least adults of the species studied are under no threat from
present or foreseeable salinities in the Murray River. 相似文献
8.
Reduction of hexavalent chromium by Pseudomonas fluorescens LB300 in batch and continuous cultures 总被引:3,自引:0,他引:3
Batch and continuous cultures of Pseudomonas fluorescens LB300 were shown to reduce hexavalent chromium, Cr(VI), aerobically at neutral pH (pH 7.0) with citrate as carbon and energy source. The product of Cr(VI) reduction was previously shown and confirmed in this work to be trivalent chromium, Cr(III), by quantitative reoxidation to Cr(VI) with KMnO4. In separate batch cultures (100 ml) containing initial Cr(VI) concentrations of 314.0, 200.0 and 112.5 mg Cr(VI) L–1, the organism reduced 61%, 69% and 99.7% of the Cr(VI), respectively. In a comparison of stationary and shaken cultures, the organism reduced 81% of Cr(VI) in 147 h in stationary culture and 80% in 122 h in shaken culture. In continuous culture, the organism lowered the influent Cr(VI) concentration by 28% with an 11.7-h residence time, by 39% with a 20.8-h residence time and by 57% with a 38.5-h residence time. A mass balance of chromium in a continuous culture at steady state showed an insignificant uptake of chromium by cells of P. fluorescens LB300.
Correspondence to: P. C. DeLeo 相似文献
9.
Teodoro JC Baptista-Neto A Cruz-Hernández IL Hokka CO Badino AC 《Applied microbiology and biotechnology》2006,72(3):450-455
First, the effect of different levels of nitrogen source on clavulanic acid (CA) production was evaluated in batch cultivations utilizing complex culture medium containing glycerol and three different levels of soy protein isolate (SPI). Cellular growth, evaluated in terms of the rheological parameter K, was highest with a SPI concentration of 30 g.L−1 (4.42 g.L−1 N total). However, the highest production of CA (380 mg.L−1) was obtained when an intermediate concentration of 20 g.L−1 of SPI (2.95 g.L−1 total N) was used. To address this, the influences of volumetric flow rate (F) and glycerol concentration in the complex feed medium (CsF) in fed-batch cultivations were investigated. The best experimental condition for CA production was F=0.01 L.h−1 and CsF=120 g.L−1, and under these conditions maximum CA production was practically twice that obtained in the batch cultivation. A single empirical equation was proposed to relate maximum CA production with F and CsF in fed-batch experiments. 相似文献
10.
The polyphasic patterns of fluorescence induction rise in pea leaves in vivo and after the treatment with ionophores have
been studied using a Plant Efficiency Analyzer. To analyze in detail photosystem II (PS II) electron transfer processes, an
extended PS II model was applied, which included the sums of exponential functions to specify explicitly the light-driven
formation of the transmembrane electric potential (ΔΨ(t)) as well as pH in the lumen (pHL(t)) and stroma (pHS(t)). PS II model parameters and numerical coefficients in ΔΨ(t), pHL(t), and pHS(t) were evaluated to fit fluorescence induction data for different experimental conditions: leaf in vivo or after ionophore
treatment at low or high light intensity. The model imitated changes in the pattern of fluorescence induction rise due to
the elimination of transmembrane potential in the presence of ionophores, when ΔΨ = 0 and pHL(t), pHS(t) changed to small extent relative to control values in vivo, with maximum ΔΨ(t) ∼ 90 mV and ΔΨ(t) ∼ 40 mV for the stationary state at ΔpH ≅ 1.8. As the light intensity was increased from 300 to 1200 μmol m−2 s−1, the heat dissipation rate constants increased threefold for nonradiative recombination of P680+Phe− and by ∼30% for P680+QA−. The parameters ΔΨ, pHS and pHL were analyzed as factors of PS II redox state populations and fluorescence yield. The kinetic mechanism of fluorescence quenching
is discussed, which is related with light-induced lumen acidification, when +QA− and P680+ recombination probability increases to regulate the QA reduction. 相似文献
11.
The harmful effects of surfactants to the environment are well known. We were interested in investigating their potential
toxicity in a pure culture of Acinetobacter junii, a phosphate (P)-accumulating bacterium. Results showed a high acute toxicity of sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium
bromide (HDTMA) against A. junii. The estimated EC50 values of the HDTMA for the inhibition of CFUs in the pure culture of A. junii was 3.27 ± 1.12 × 10−7 mol L−1 and for the inhibition of the P-uptake rates 2.47 ± 0.51 × 10−6 mol L−1. For SDS, estimated EC50 values for the inhibition of CFUs in the pure culture of A. junii was 5.00 ± 2.95 × 10−6 mol L−1 and for the inhibition of the P-uptake rates 3.33 ± 0.96 × 10−4 mol L−1. The obtained EC50 values in the standardised yeast toxicity test using Saccharomyces cerevisiae were 3.03 ± 0.38 × 10−4 and 4.33 ± 0.32 × 10−5 mol L−1 for SDS and HDTMA, respectively. These results emphasized the need to control concentrations of surfactants entering the
activated sludge system. The negative effects of these toxicants could greatly decrease populations of P-accumulating bacteria,
as well as eukaryotic organisms, inhabiting activated sludge systems, which in turn could result in the decrease of the system
efficiency. 相似文献
12.
Barrera-Cortés J Manilla-Pérez E Poggi-Varaldo HM 《Bioprocess and biosystems engineering》2006,29(5-6):391-398
The objective of this work was to determine (1) the effect of rotational speed (N) and lifters on the oxygen transfer coefficient (k
L) of a mineral solution and (2) the effect of solids concentration of a slurry soil-mineral solution on k
L, at a fixed value N (0.25 s−1); in both cases the treatment was carried out in an aerated rotating drum reactor (RDR) operated at atmospheric pressure. First, the k
L for the mineral solution was in the range 6.38 × 10−4–7.69 × 10−4 m s−1, which was of the same order of magnitude as those calculated for closed rotating drums supplied with air flow. In general, k
L of RDR implemented with lifters was superior or equal to that of RDR without lifters. For RDR implemented with lifters, k
L increased with N in the range 6.65 × 10−4–10.51 × 10−4 m s−1, whereas k
L of RDR without lifters first increased with N up to N = 0.102 s−1, and decreased beyond this point. Second, regarding soil slurry experiments, an abrupt fall of k
L (ca. 50%) at low values of the solid concentration (C
v) and an asymptotic pattern at high C
v were observed at N = 0.25 s−1. These results suggest that mass transfer phenomena were commanded by the slurry properties and a semi-empirical equation of the form Sh = f(Re, Sc) seems to corroborate this finding. 相似文献
13.
Héctor Guzmán Doan Van-Thuoc Javier Martín Rajni Hatti-Kaul Jorge Quillaguamán 《Applied microbiology and biotechnology》2009,84(6):1069-1077
The paper reports a study involving the use of Halomonas boliviensis, a moderate halophile, for co-production of compatible solute ectoine and biopolyester poly(3-hydroxybutyrate) (PHB) in a
process comprising two fed-batch cultures. Initial investigations on the growth of the organism in a medium with varying NaCl
concentrations showed the highest level of intracellular accumulation of ectoine (0.74 g L−1) at 10–15% (w/v) NaCl, while at 15% (w/v) NaCl, the presence of hydroxyectoine (50 mg L−1) was also noted. On the other hand, the maximum cell dry weight and PHB concentration of 10 and 5.8 g L−1, respectively, were obtained at 5–7.5% (w/v) NaCl. A process comprising two fed-batch cultivations was developed—the first culture aimed at obtaining high cell mass
and the second for achieving high yields of ectoine and PHB. In the first fed-batch culture, H. boliviensis was grown in a medium with 4.5% (w/v) NaCl and sufficient levels of monosodium glutamate, NH4+, and PO43−. In the second fed-batch culture, the NaCl concentration was increased to 7.5% (w/v) to trigger ectoine synthesis, while nitrogen and phosphorus sources were fed only during the first 3 h and then stopped
to favor PHB accumulation. The process resulted in PHB yield of 68.5 wt.% of cell dry weight and volumetric productivity of
about 1 g L−1 h−1 and ectoine concentration, content, and volumetric productivity of 4.3 g L−1, 7.2 wt.%, and 2.8 g L−1 day−1, respectively. At salt concentration of 12.5% (w/v) during the second cultivation, the ectoine content was increased to 17 wt.% and productivity to 3.4 g L−1 day−1. 相似文献
14.
Swati N. Yewalkar Kondiram. N. Dhumal Jayashree K. Sainis 《Journal of applied phycology》2007,19(5):459-465
We isolated four cultures of chromate resistant, unicellular, non-motile green algae from disposal sites of the paper-pulp
and electroplating industries. These algae were maintained in Tris-acetate-glycerophosphate medium containing 30 μM K2Cr2O7. The morphological features as well as analysis of the 500-bp fragment of 18S rDNA (NS 12 region) showed that these isolates
belong to Chlorella spp. These isolates showed EC50 values for chromate ranging from 60 to 125 μM. Uptake studies with radioactive 51Cr(VI) showed that 10–19% of total radioactivity was intracellular, and 1–2% was bound to the cell wall. The rest of the activity
remained in the medium, suggesting that resistance was not related to accumulation of Cr(VI) in the cells. Interestingly,
when these isolates were grown in the presence of 30 μM of K2Cr2O7, a decrease in the Cr(VI) concentration in the medium was observed. Only live cells could deplete Cr(VI) from the supernatant,
suggesting the presence of chromium reduction activity in these Chlorella isolates. Cr(VI) reduction activity of the cells of Chlorella was stimulated by light as well as by acetate and glycerophosphate. Treatment of Chlorella cells with 3-(3,4 dichlorophenyl),1,1dimethyl urea (DCMU) did not affect the Cr(VI) reduction. However, if the cells were
treated with sodium azide, Cr(VI) reduction was severely affected. Though chromate resistance has been well documented in
algae, the information on chromate reduction by algae is scant. This paper discusses the Cr(VI) reduction by Cr(VI) resistant
Chlorella, which may find a use in the effective bioremediation of Cr(VI). 相似文献
15.
Alfalfa (Medicago sativa L.) was grown in greenhouse sand culture to examine the effect of salinity composition and concentration on Se accumulation
by plants. In a 2×2×4 factorial experiment, salinity was added as either C1− or SO
4
2−
salts to the irrigating solution to achieve an electrical conductivity of 0.5, 1.5–3.0, or 6.0 dS m−1. Selenium was added to the nutrient solution at a concentration of 0.25 or 1.0 mg Se(VI)I−1. Following the third cutting, the roots were washed and all plant material analyzed for dry weight and Se. Plant biomass
production decreased with additions of either Se or salinity, regardless of composition. In the presence of Se, the yield
reduction was greater with Cl− salinity than with SO
4
2−
salinity. Plant Se accumulation was reduced from 948 mg Se kg−1 to 6 mg Se kg−1 in the presence of SO
4
2−
salts (0.5 mmol SO
4
2−
l−1
vs. 40 mmol SO
4
2−
l−1) due to an apparent Se(VI) −SO
4
2−
antagonism. This Se−SO
4
2−
antagonism prevented accumulation of Se and reduced Se-induced toxicity. A lesser antagonistic effect on Se accumulation
was observed between Cl−, and Se. A synergistic interaction between SO
4
2−
and Se(VI) increased plant S concentrations in the presence of the relatively low basal SO
4
2−
concentrations but not at the higher solution SO
4
2−
concentrations. In many areas, soil and water containing high Se concentrations also contain large amounts of SO
4
2−
. The occurrence of SO
4
2−
with Se reduces plant accumulation of Se(VI) and may lower the risk of Se overexposure to animals feeding on forage material
grown in high Se−SO
4
2−
regions. 相似文献
16.
Neuronal ion channels of different types often do not function independently but will inhibit or potentiate the activity of
other types of channels, a process called cross-talk. The N-methyl-D-aspartate receptor (NMDA receptor) and the γ-aminobutyric acid type A receptor (GABAA receptor) are important excitatory and inhibitory receptors in the central nervous system, respectively. Currently, cross-talk
between the NMDA receptor and the GABAA receptor, particularly in the central auditory system, is not well understood. In the present study, we investigated functional
interactions between the NMDA receptor and the GABAA receptor using whole-cell patch-clamp techniques in cultured neurons from the inferior colliculus, which is an important
nucleus in the central auditory system. We found that the currents induced by aspartate at 100 μmol L−1 were suppressed by the pre-perfusion of GABA at 100 μmol L−1, indicating cross-inhibition of NMDA receptors by activation of GABAA receptors. Moreover, we found that the currents induced by GABA at 100 μmol L−1 (I
GABA) were not suppressed by the pre-perfusion of 100 μmol L−1 aspartate, but those induced by GABA at 3 μmol L−1 were suppressed, indicating concentration-dependent cross-inhibition of GABAA receptors by activation of NMDA receptors. In addition, inhibition of IGABA by aspartate was not affected by blockade of voltage-dependent Ca2+ channels with CdCl2 in a solution that contained Ca2+, however, CdCl2 effectively attenuated the inhibition of I
GABA by aspartate when it was perfused in a solution that contained Ba2+ instead of Ca2+ or a solution that contained Ca2+ and 10 mmol L−1 BAPTA, a membrane-permeable Ca2+ chelator, suggesting that this inhibition is mediated by Ca2+ influx through NMDA receptors, rather than voltage-dependent Ca2+ channels. Finally, KN-62, a potent inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMKII), reduced the inhibition of I
GABA by aspartate, indicating the involvement of CaMKII in this cross-inhibition. Our study demonstrates a functional interaction
between NMDA and GABAA receptors in the inferior colliculus of rats. The presence of cross-talk between these receptors suggests that the mechanisms
underlying information processing in the central auditory system may be more complex than previously believed. 相似文献
17.
Francisco J. Cervantes Edna R. Meza-Escalante Anne-Claire Texier Jorge Gómez 《Journal of industrial microbiology & biotechnology》2009,36(11):1417-1424
The aim of this study was to evaluate the capacity of a denitrifying consortium to achieve the simultaneous removal of nitrate,
sulfide and p-cresol and elucidate the rate-limiting steps in the mixotrophic process. Nitrite reduction appeared as the most evident rate-limiting
step in the denitrifying respiratory process. The nitrite reduction rate achieved was up to 57 times lower than the nitrate
reduction rate during the simultaneous removal of sulfide and p-cresol. Negligible accumulation of N2O occurred in the denitrifying cultures corroborating that nitrite reduction was the main rate-limiting step of the respiratory
process. A synergistic effect of nitrate and sulfide is proposed to explain the accumulation of nitrite. The study also points
at the oxidation of S0 as another rate-limiting step in the denitrifying process. Different respiratory rates were achieved with the distinct electron
donors provided (p-cresol and sulfide). The oxidation rate of p-cresol (qCRES) was generally higher (up to 2.6-fold in terms of reducing equivalents) than the sulfide oxidation rate (qS2−), except for the experiments performed at 100 mg S2− L−1 in which qS2− was slightly (~1.4-fold in terms of reducing equivalents) higher than qCRES. The present study provides kinetic information, which should be considered when designing and operating denitrifying reactors
to treat industrial wastewaters containing large amounts of sulfurous, nitrogenous and phenolic contaminants such as those
generated from petrochemical refineries. 相似文献
18.
The reduction of Cr(VI) to Cr(III) is a potential detoxification process. In this study, seven Pseudomonas spp. were isolated and screened for chromium reduction. Isolate P4 was able to grow in the presence of 8000 μM chromium, in spite of the fact that the isolate was not previously exposed to any metal stress. Isolate P4 was identified as Pseudomonas aeruginosa strain SRD chr3 by 16S rDNA sequence analysis. Shake flask study showed 78% reduction of 1000 μM Cr(VI) after 6 h of incubation. The optimum pH for chromium reduction by the isolate was between 6 and 8. Isolate Pseudomonas aeruginosa gave 50–80% Cr(VI) reduction even in the presence of 100 mM of Cu, Mn, Ni, and Zn and 300–800 mM NaCl in 24 h, compared with the absence of any of these metals. In a 5-L reactor, the isolate showed 84.85% reduction of Cr(VI) even at the 70th cycle, with a hydraulic retention time of 24 h from the effluent of a hard chrome plating (electroplating) industry, which contained 2100 mg L?1 hexavalent chromium. The chromate-amended soil inoculated with the isolate showed 2800 μM chromium removal from 4000 μM Cr(VI) kg?1 of soil, which corresponds to 70% removal. The isolate had the ability to degrade stimulated waste containing 10,000 μM chromium. 相似文献
19.
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
20.
Battaglia-Brunet F Foucher S Denamur A Ignatiadis I Michel C Morin D 《Journal of industrial microbiology & biotechnology》2002,28(3):154-159
The ability of sulfate-reducing bacteria (SRB) to reduce chromate, Cr(VI), was evaluated using fixed-film growth systems and
H2 as the electron source. A main objective of the experiment was to distinguish between direct enzymatic reduction and indirect
reduction by hydrogen sulfide, in order to subsequently verify and control the synergy of these two mechanisms. In batch experiments
with the sulfate-reducing consortium CH10 selected from a mining site, 50 mg l−1 Cr(VI) was reduced in 15 min in the presence of 500 mg l−1 hydrogen sulfide compared to 16 mg l−1 reduced in 1 h without hydrogen sulfide. Fixed films of a CH10 population and Desulfomicrobium norvegicum were fed-batch grown in a column bioreactor. After development of the biofilm, hydrogen sulfide was removed and the column
was fed continuously with a 13-mg l−1 Cr(VI) solution. Specific Cr(VI) reduction rates on pozzolana were close to 90 mg Cr(VI) h−1 per gram of protein. Exposure to Cr(VI) had a negative effect on the subsequent ability of CH10 to reduce sulfate, but the
inhibited bacteria remained viable. Journal of Industrial Microbiology & Biotechnology (2002) 28, 154–159 DOI: 10.1038/sj/jim/7000226
Received 20 September 2000/ Accepted in revised form 13 November 2001 相似文献