Bioremediation Of Cadmium Research Articles

Molecular characterization of marine bacterial isolates of Visakhapatnam coast—efficacy in dye decolorization and bioremediation of cadmium

BackgroundMicrobial community is one of the diversified communities of the marine environment. Studies have shown that microorganisms isolated from the marine environment are metabolically active and have adapted to life in the ocean. The marine microorganisms use various survival strategies to combat heavy metal stress and decolorization of various textile dyes, thus playing an important role in the bioremediation of cadmium and degradation of textile dyes. The present study deals with the isolation and 16S rRNA molecular characterization of M3 and M8 bacterial strains isolated from marine water samples collected from Visakhapatnam harbor. M3 and M8 isolates were also checked for their efficacy in the removal of cadmium and decolorization of various textile dyes from the environment. ResultsThe water sample was subjected to tube dilution method to isolate bacterial strains, and ten different isolates were screened. The biochemical tests were performed for the isolates to prove their validity and 16S rRNA molecular sequencing and phylogenetic analysis for species identification. Out of interest, two bacterial strains, namely, M3 and M8 were subjected to 16S rRNA molecular sequencing and phylogenetic analysis and were identified as Bacillus subtilis and Pseudomonas resinovorans. The two bacterial strains showed promising dye degradation property when checked with nine different textile dyes of wavelength ranging from 400 to 600 nm and removal of cadmium from the growth medium. ConclusionThe present study demonstrates the isolates M3 and M8 to be potential strains having dye decolorization and bioremediation of cadmium applications.

Threonine dehydratase enhances bacterial cadmium resistance via driving cysteine desulfuration and biomineralization of cadmium sulfide nanocrystals

Biomineralization is often used by microorganisms to sequester heavy metal ions and provides a potential means for remediating increasing levels of heavy metal pollution. Bacteria have been shown to utilize cysteine for the biomineralization of metal sulfide. Indeed, in the present study, the supplement of L-cysteine was found to significantly improve both cadmium resistance and removal abilities of a deep-sea bacterium Pseudomonas stutzeri 273 through cadmium sulfide (CdS) nanoparticle biomineralization. With a proteomic approach, threonine dehydratase of P. stutzeri 273 (psTD) was proposed to be a key factor enhancing bacterial cadmium resistance through catalyzing L-cysteine desulfuration, H2S generation and CdS nanoparticle biomineralization. Consistently, deletion of the gene encoding psTD in P. stutzeri 273 resulted in the decline of H2S generation, decrease of cadmium resistance, and reduction of cadmium removal ability, confirming the unique function of psTD directing the formation of CdS nanoparticles. Correspondingly, the single-enzyme biomineralization of CdS nanoparticle driven by psTD was further developed, and psTD was shown to act as a capping reagent for the mineralization reaction, which controlling the size and structure of nanocrystals. Our results provide important clues for the construction of engineered bacteria for cadmium bioremediation and widen the synthesis methods of nanomaterials.

Nuevos agentes de biorremediación de cadmio: Especies de Trichodermanativas de la rizósfera de árboles de cacao

Nuevos agentes de biorremediación de cadmio: Especies de Trichodermanativas de la rizósfera de árboles de cacao

Co-Cultivation of Leptolyngbya tenuis (Cyanobacteria) and Chlorella ellipsoidea (Green alga) for Biodiesel Production, Carbon Sequestration, and Cadmium Accumulation.

The co-cultivation approach using cyanobacteria-Leptolyngbya tenuis and green alga-Chlorella ellipsoidea demonstrated in the present study showed additive and synergistic effects on biomass yield, biomass productivity, lipid yield, lipid productivity, CO2 fixation, and cadmium bioremediation efficiency. The results of co-culture in batch mode revealed about 2-3 times increase in biomass and two times increase in total lipid, when compared to the pure culture batches. The results revealed that co-cultures exhibited significantly high CO2 fixation rate of 2.63 ± 0.09g/L/d, which is 1.5-2 times better than monocultures (P < 0.05). To explore the bioaccumulation of cadmium by co-cultures and pure cultures, different concentrations of cadmium nitrate was used in flask trials. Cadmium accumulation was observed in the order: co-culture (74%, 0.37mg/L) > Chlorella (58%, 0.29mg/L) > Leptolyngbya (50%, 0.25mg/L) (P < 0.05). In addition, fatty acid composition, CHNS analysis, biodiesel characterization, and biochemical compositions were also determined using co-culture method. The maximum biomass yield, productivity, lipid content, and CO2 fixation rate in cadmium induced co-culture were 3.95 ± 0.13g/L, 258.88 ± 15.75mg/L/d, 41.43 ± 0.71%, and 3.21 ± 0.20g/L/d, respectively which is 1.2, 1.3, 2.3, and 1.2 times higher than the control (P < 0.05). Cadmium induced changes in growth and lipid yield using co-culture suggests cost-effective and eco-friendly production of biodiesel and carbon mitigation.

Cadmium tolerance and bioremediation potential of filamentous fungus Penicillium chrysogenum FMS2 isolated from soil

Cadmium-tolerant fungus, designated as strain FMS2, was isolated from metal-polluted soil collected from Lahore, Pakistan, and its role in cadmium bioremediation was investigated. Strain FMS2 was identified as Penicillium chrysogenum through sequence analysis of the internal transcribed spacer (ITS) regions. Physicochemical growth factors and maximum tolerance level to cadmium were determined. Cadmium uptake and bioremoval potential were analyzed by atomic absorption spectrophotometry, scanning electron microscopy and energy-dispersive spectroscopic analysis, whereas its distribution inside the fungal cell was detected by scanning transmission electron microscopy and electron energy loss spectroscopy. P. chrysogenum FMS2 was found to be resistant to cadmium with a maximum tolerance level up to 1000 mg l−1. Strain FMS2 can grow under a wide range of temperature (15–35 °C) and pH conditions (4.0–12.0). The cadmium removal capacity of strain FMS2 was observed as 49 ± 0.8% within 15 days after exposure. Distinct white patches were observed in scanning electron micrographs with clear peaks of cadmium in energy-dispersive spectroscopic spectra indicating cadmium biosorption. The scanning transmission electron micrographs and electron energy loss spectra of strain FMS2 cells revealed cytoplasmic localization of cadmium.

Effects of magnetic biochar-microbe composite on Cd remediation and microbial responses in paddy soil

There is growing global interest in the bioremediation of cadmium (Cd) using combinations of biochar and microorganisms. However, the interactions among biochar, introduced and indigenous microorganisms remain unclear. Accordingly, a 90 day microcosm experiment was conducted to investigate this by adding Bacillus sp. K1 strain inoculated rice straw biochar (SBB) and magnetic straw biochar (MBB) into a Cd contaminated paddy soil from Hunan, China. All treatments were incubated aerobically (60% water holding capacity) or anaerobically for 90 d. During both soil incubations, Bacillus sp. K1 successfully colonized in soil with composites applications. Soil pH was significantly increased from acid to neutral, and available Cd decreased with the addition of both composites. The better remediation efficiency of MBB than SBB under anerobic conditions was attributed to the transformation of acetic acid-extractable Cd into the residual fraction, caused by Cd2+ bonding with crystal Fe3O4. The application of the two kinds of composites caused similar changes to both microbial communities. There was a slight decrease in indigenous microbial alpha diversity with the MBB aerobic application, while the total population number of bacteria was increased by 700%. Both the redundancy analysis and Mantel analyses indicated that pH and microbial biomass C contributed to the colonization of Bacillus sp. K1 with SBB under aerobic conditions, and with MBB under anerobic conditions, respectively. The research provides a new insight into interactive effects and investigates immobilization mechanisms involved of bacterial/biochar composites in anaerobic and aerobic soils.

Toxic metals bioremediation potentials of Paenibacillus sp. strain SEM1 and Morganella sp. strain WEM7 isolated from Enyigba Pb–Zn mining site, Ebonyi State Nigeria

Heavy metal contamination is a serious environmental and ecological problem currently facing many countries. Discovering a novel biological means of detoxifying environments contaminated with these heavy metals is an urgent necessity. More so, an efficient bio-remediating agent from biological sources would be cost effective, climate change friendly and easily accessible with less negative effects on the environment. We report a novel study on heavy metals’ tolerant and bioremediation potentials of Penibacills sp. Strain SEM1 and Morganella sp. Strain WEM7 isolated from Enyigba Pb–Zn mining site, Ebonyi State, Nigeria. The result revealed that the bacteria isolates optimally thrived in media containing 5–15% of sodium chloride. The SEM1 showed capacity to tolerate lead, mercury and nickel up to 10,000 mg/l, up to 1400 mg/l for cadmium and up to 2500 mg/l each of copper and zinc. Additionally, WEM7 resisted zinc, copper and nickel up to 2500 mg/kg, mercury and cadmium up to 630 and 700 mg/kg respectively and more than 10,000 mg/kg of lead in both solid and liquid media. The 16S rRNA gene assay and phenotypic physiognomies of SEM1 and WEM7 strains fit in the genus Paenibacillus and Morganella respectively. The trend of heavy metals removal by SEM1 is as follows: Ni > Pb > Hg > Cu > Zn > Cd (97.62, 96.84, 90, 86.36, 84.85, 70%) and that of WEM7: Cu > Ni > Pb > Hg > Zn > Cd (100, 98.64, 97.48, 93.33, 80.85, 68.42%). Our investigation revealed that the isolates, SEM1 and WEM7 are moderately halophilic, metalophiles and could provide exceptional novel tool for mercury, lead, cadmium, nickel, copper and zinc bioremediation in contaminated environments.

The relationship between the oxidative stress reaction and the microbial community by a combinative method of PA and CCA

Earthworms, as the first choice for soil monitoring and bio-remediation of cadmium (Cd)-contaminated soil, need to identify its mechanism under Cd stress. In this study, an artificial soil test method was used to determine the oxidative stress reaction indices, amino acid composition, and microbial community changes in earthworms under different stress durations and concentrations. For the first time, the canonical correlation analysis model and path analysis model were innovatively introduced into the data analysis to determine the mechanism that drives earthworm physiological functions after Cd stress. The results showed that in the low-stress concentration treatments (50–125 mg.kg−1 DW), there was a driving relationship between oxidative stress reaction and microbial community in earthworm, and the driving factor was glycyl-L-glutamic acid at 50 mg.kg−1 DW. With the increase of Cd stress intensity, the enzymes of oxidative stress promoted the survival microbes to begin to proliferate, and SOD became the main driving factor under 125 mg.kg−1 DW Cd stress. In the high-stress concentration treatments (250–500 mg.kg−1 DW), the driving effects were weakened or disappeared; while Cd-resistant microbial population appeared. This study provides a theoretical basis for the driving mechanism between oxidative stress effect and microbial community after Cd stress.

Evaluation of cadmium biosorption property of de-oiled palm kernel cake

Cadmium contamination is a global concern because of its widespread nature of polluting both biotic and abiotic components of ecosystem. Though many natural, chemical/synthetic components have been researched for remediation of cadmium, development of an eco-friendly, economic biosorbent still remains a challenge. Deoiled palm kernel cake (DOPC), a byproduct from palm-oil mills was investigated in the present study for its cadmium remediating capacity. DOPC was immobilized using sodium alginate polymer and biosorption studies were carried out using DOPC as adsorbent for removal of cadmium. Research revealed biosorption potential of DOPC and the optimum conditions for maximum biosorption of cadmium have been identified as 120 min of contact time, 150 rpm of agitation speed, pH 6 and 15 mg/L of initial cadmium concentration. Maximum percentage of adsorption was 99% by using 1.5 g/100 ml of adsorbent. The adsorption equilibrium data Biosorbent was characterized before and after adsorption by FTIR which showed the involvement of carboxyl, hydroxyl and amino-groups. Statement of novelty Cadmium pollution and the leading environmental problems is a global concern. Despite various attempts for development of different matrices for remediation of cadmium from contaminated samples, application of deoiled palm kernel cake (DOPC) as a biosorbent is not being explored. Present study provides quantitative data relating the richness of phytochemical repertoire DOPC possess, its resulting radical scavenging potential and its applications as an efficient, eco-friendly and economic alternative as a biosorbent matrix material for cadmium bio-remediation.

Bioremediation of cadmium in a sandy and a clay soil by microbially induced calcium carbonate precipitation after one week incubation

Microbially induced calcium carbonate precipitation (MICP) method can convert heavy metals from mobile forms into more stable crystals. This study was conducted to investigate the removal of cadmium (Cd) by Sporosarcina pasteurii through the urea hydrolysis pathway. Cd removal from solution containing 0.5, 1, and 2 mmol l−1 of Cd (as CdCl2.5H2O) were measured firstly, and then the amount of Cd removal was studied in two sandy and clay soils containing 10, 20, 40, and 50 mg kg−1 of Cd. The experiments were arranged in complete randomized design with three replications. Minimum inhibitory concentration (MIC) of Cd for bacteria growth was attained as 2 mmol l−1, after 48 h of incubation. Cd removal efficacy was 99.6% in 0.5 mmol l−1 and 99.8% in 1 and 2 mmol l−1 Cd solutions. In both soils that were inoculated with bacteria, Cd concentration decreased in solution-exchangeable fraction significantly (p ≤ 0.05). The Cd concentration in the solution-exchangeable fraction of sandy and clay soils were decreased to 85.9, 61.1, 74.3, 80.3% and 89.3, 86.6, 76, 75.6% of its initial values (i.e., 10, 20, 40, and 50 mg kg−1), respectively. The amount of Cd in carbonate fraction in both sandy and clay soil increased significantly in the presence of bacteria (p ≤ 0.05). The results revealed that MICP-based removal of heavy metals via co-precipitation with calcite not only immobilized Cd in studied soils but also improved the microbial and enzymatic activities.

Bioremediation of cadmium polluted soil using a novel cadmium immobilizing plant growth promotion strain Bacillus sp. TZ5 loaded on biochar

Bioremediation of cadmium polluted soil using biochar (BC) and plant growth promotion bacteria (PGPB) have been widely concerned. In our study, a novel Cd immobilizing PGPB strain TZ5 was isolated based on the Cd immobilizing potential and plant growth promotion (PGP) traits. Further, changes of surface morphology and functional groups of TZ5 cells were observed after exposed to Cd2+ by SEM-EDS and FTIR analyses. Then, the strain TZ5 was successfully loaded on BC as biochemical composites material (BCM). Pot experiment indicated that the percentage of acetic acid-extractable Cd in BCM treatments significantly decreased by 11.34 % than control. Meanwhile, BCM significantly increased the dry weight of ryegrass by 77.78 %, and decreased the Cd concentration of ryegrass by 48.49 %, compared to control. Microbial counts and soil enzyme activities in rhizosphere were both significantly improved by BCM. Furthermore, the proportion of relative abundance of Bacillus genus was enhanced after treated by BCM, which indicated that the strain TZ5 was successfully colonized in the rhizosphere. This study provided a practical strategy for bioremediation of Cd contaminated soil.

Bioremediation of lead and cadmium and the strive role of Pediococcus pentosaceus probiotic

Bioremediation of lead and cadmium and the strive role of Pediococcus pentosaceus probiotic

Abilities of Three Microorganisms for Cleaning Cadmium Contaminated Soils

The abilities of three indigenous bacteria for bioremediation of cadmium contaminated soils collected from Agbabu Farm Settlement close to mining sites in Ondo state, Nigeria was studied to provide helpful information for soils remediation and soils health management in this sub-region for Millennium Development Goals accomplishment. Bacillus subtilis, Proteus mirabilis, and Escherichia coli isolated from the soils were inoculated into different soil samples conditioned with optimized factors determined from the first phase experiments. The conditioned samples were experimented for residual cadmium concentration with time in days using Atomic Absorption Spectrophotometer. The soil cadmium attenuation from the initial concentration of 70.21 mg/kg to below the maximum allowable of 3 mg/kg was hard for the organisms. Bacillus subtilis performed correction at time 35 days with an efficiency of 96.10 % and residual concentration of 2.74 mg/kg. Proteus mirabilis and Escherichia coli with respective, high efficiencies of 85.05% and 79.35% failed. The removal rate capacities were -0.131d-1 for B. subtilis; -0.111d-1 for P. mirabilis; -0.105d-1 for E. coli. Four kinetic models fitted described the experimental data well. The models assessment revealed the removals to be transport controlled as diffusion process was the rate-controlling step.

Optimizing the Management of Cadmium Bioremediation Capacity of Metal-Resistant Pseudomonas sp. Strain Al-Dhabi-126 Isolated from the Industrial City of Saudi Arabian Environment.

In this study, 23 bacterial strains were isolated from a Cadmium (Cd) contaminated soil in the industrial city, Riyadh of Saudi Arabia. Among these isolates six strains were found to withstand cadmium contamination and grow well. From the six isolates Pseudomonas sp. strain Al-Dhabi-122–127 were found to resist cadmium toxicity to a higher level. The isolates were subjected to biochemical and 16S rDNA gene sequence characterization to confirm their identification. The bacterial strain Al-Dhabi-124 showed 1.5 times higher Cd-degrading activity than Al-Dhabi-122 and Al-Dhabi-123, and Al-Dhabi-126 exhibited 3.5 times higher Cd-degrading activity, higher than the other strains. An atomic absorption spectrophotometer study showed that the strain Al-Dhabi-126 absorbed Cd, and that the bacterial strain Al-Dhabi-126 was found to tolerate cadmium level up to 2100 µg/mL. The bacterial strain Al-Dhabi-126 showed a maximum Cd removal efficacy at pH between 6.0 and 8.0. The efficacy decreased sharply after an increase in pH (9.0). An optimum temperature of 50 °C and pH 6.0 were found to be effective for the Cd removal process by the isolate. The study indicated that the bacterial strain Al-Dhabi-126 can be used effectively for the bioremediation of heavy metals like cadmium, a major toxic pollutant in industrial effluents.

Bioremediation of Cadmium Contaminated Effluent by Sporosarcina luteola: A Bacterium Isolated from Soil near Wazirpur Industrial Area, New Delhi, India

Heavy metals pollution is emerging as a threat to ecological systems causing various problems to mankind, plants and animals. Aim of the present study was to isolate and identify cadmium tolerant bacteria from the soil of Wazirpur industrial area of New Delhi (India). The study involved physico-chemical characterization of the polluted soil which was found to contain high concentration of iron, manganese and cadmium at 352, 15.3 g/kg soil and 3.16 ppm, respectively. One bacterial strain was identified as Sporosarcina luteola on the basis of morphological, biochemical and phylogeny analysis. Strain Sporosarcina luteola was highly resistant to Cd up to 5mM (mM= millimolar) when cultured in solidified nutrient agar plates and 7.2 mM in nutrient broth. Sporosarcina luteola has also showed substantial growth in presence of Co, Pb, Fe and Mn upto 2.0, 2.0, 3.5 and 4.0 mM, respectively in liquid medium. Optimum growth of identified bacteria was shown at 37 ºC, 7.0 pH and it tolerated up to 3 % sodium chloride (w/v). This is reported for the first time that Sporosarcina luteola (metal-tolerant bacteria) has potential of removal of cadmium from industrially contaminated soil.

Remediation and Mechanisms of Cadmium Biosorption by a Cadmium-Binding Protein from Lentinula edodes.

Cadmium bioremediation with metal-binding proteins is primarily conducted using metallothioneins (MTs). However, in the present study, we investigated a non-MT cadmium-binding protein from Lentinula edodes (LECBP) as a remediation tool for cadmium biosorption in Escherichia coli. The results indicated that the expression of LECBP significantly enhanced the cadmium biosorption capacity of transgenic E. coli. The secondary structure and conformation of LECBP were changed after binding with cadmium as evidenced by circular dichroism and fluorescence spectroscopy. The results of Fourier transform infrared spectroscopy indicated that carboxyl oxygen and amino nitrogen atoms were involved in the interaction between LECBP and cadmium. The results further demonstrated that glutamic acid and histidine residues are the potential binding sites. Our results have thus provided new insights into cadmium bioremediation in an aquatic environment.

The performance of biochar-microbe multiple biochemical material on bioremediation and soil micro-ecology in the cadmium aged soil

Biochar (BC) and plant growth promoting bacteria (PGPR) have been widely applied to improve the qualities of heavy metal contaminated soil, while the synergy effect of BC and PGPR on the bioremediation of cadmium (Cd) contaminated soil was less studied. In this study, a novel PGPR strain SNB6 was isolated and then immobilized on BC as the multiple biochemical material (BCM) as well as combined with vetiver grass (Chrysopogon zizanioides L.) to form BC-PGPR-accumulator system. The promoting effects of BCM on bioremediation and soil micro-biology were comprehensively investigated. SEM and FTIR analysis indicated that the strain SNB6 was successfully fixed on BC and the functional groups between BC and SNB6 surface contributed to the immobilization effect. The BCM significantly enhanced the Cd content and bioaccumulation factor (BCF) of accumulator, about 412.35% and 403.41% higher than that of control, respectively. Meanwhile, the biomass of fresh and dry accumulator in the BCM treatment was 227.27% and 178.33% higher than that of control. In addition, the system significantly increased the proportion of HOAc-extractable Cd and soil micro-ecology. Microbial counts and soil enzyme activities in rhizosphere were both significantly improved by the interaction of BCM and C. zizanioides. Furthermore, the strain SNB6 in the rhizosphere interface was successfully colonized, and soil microbial community was evaluated to understand the microbial diversity after bioremediation. Our study indicated that the BCM could significantly enhance the bioremediation efficiency and drive the soil micro-ecology, and the BC-PGPR-accumulator system provided a feasible pathway to remediate heavy metal contaminated sites.

Bioaccumulation and distribution of cadmium by Burkholderia cepacia GYP1 under oligotrophic condition and mechanism analysis at proteome level

Bacteria have been applied for the bioremediation of cadmium-contaminated environment. Less is known about the bioaccumulation of high concentration of Cd over time under the oligotrophic environment. Burkholderia cepacia GYP1, which was isolated from multiple heavy metal contaminated farmland, was studied for its bioaccumulation mechanism of Cd under oligotrophic condition. GYP1 possessed highly accumulation capacity for cadmium reaching 116 mg Cd/g biomass (dry weight). ATR-FTIR, electron microscopy, flow cytometry along with subcellular fraction demonstrated that the uptake and distribution of cadmium varied with the increased amount of cadmium of GYP1 cell during the 7-day treatment time: the accumulation of cadmium was mainly on the outer membrane at the beginning (within 1 day), and the intracellular cadmium kept increased and held stable after 2 days, after that, the increased amount of cadmium mainly located extracellularly, related to the secreted EPS. Further mechanism analysis of bioaccumulation of Cd by GYP1 based on iTRAQ-based proteomics showed that Cd(II) could trigger the up-regulation of the Cd2+/Zn2+-exporting ATPase, type VI protein secretion systems, and glutathione-S-transferase that are related to cadmium response, which may contribute to maintain the intracellular cadmium homeostasis. In summary, the immobilization of Cd(II) by B. cepacia GYP1 contains three steps:(1) fast immobilization of Cd(II) on the cell surface coordinated with functional groups, (2) transport of Cd(II) to cells and accumulation in cytoplasm, and (3) efflux of intracellular Cd(II) depended on energy and the entrapped or adsorbed of extracellular Cd(II) by EPS. Our study provided the understanding of the cadmium accumulation process of B. cepacia GYP1 under oligotrophic condition, which would be helpful in bioremediation of natural cadmium contaminated environment.

Cadmium and lead removal by new bacterial isolates from coal and aluminum mines

Heavy metals such as cadmium have dangerous effects on ecosystem and human health. In this study, the bacteria diversity of soil samples of coal, salt and aluminum mines and water sample of Mareh wetland of Iran were investigated and their potential to cadmium removal was assessed. Based on partial sequencing of 16S region, the 64 isolates were identified that water sample of Mareh wetland showed high bacterial diversity. Among the isolated bacterial, 11 isolates from 10 different genus including Leifsonia sp., Rhodococcus sp., Bacillus sp., Microbacterium sp., Enterobacter sp., Planomicrobium sp., Microbacterium sp., Thalassospira sp., Brevundimonas sp., Halomonas sp. and Micrococcaceae sp. (could grow under 50 mg/L CdCl2) were selected to consider the cadmium bioremediation potential. The Microbacterium oxydans CM3 and Rhodococcus sp. AM1 as new strains exhibited high ability to removal of cadmium and also degraded 58 and 39% of 400 mg/L lead after 72 h of incubation, respectively. Our result revealed that M. oxydans strain CM3 as natural way has a great potential for absorbing and degrading the heavy metal such as cadmium and lead.

Role of novel bacterial Raoultella sp. strain X13 in plant growth promotion and cadmium bioremediation in soil.

Heavy metal pollution in agricultural soils has become a widespread serious problem with the rapid industrialization and urbanization in the past two decades. Cadmium (Cd2+) is of the most concern in soils due to its high toxicity. It is necessary to develop remediation strategies to remove or neutralize its toxic effects in Cd-contaminated soil. Microbial bioremediation is a promising technology to treat heavy metal-contaminated soils. In this study, Cd-resistant bacterium, isolated from heavy metal-polluted soil in Southern China, was characterized as Raoultella sp. strain X13 on the basis of its biochemical profile and 16S rRNA. We investigated the characterization of Cd2+ distribution in different cellular compartments after Cd2+ uptake. Cd2+ uptake by strain X13 was mainly by ion exchange and chelation binding tightly to the cell wall. In addition, X13 plant growth-promoting characteristics suggested that X13 could solubilize phosphate and produce indole acetic acid. Pot experiments for the remediation of Cd-contaminated soil in situ by X13 inoculation demonstrated that X13 application to Cd-contaminated soils significantly promoted pak choi growth and improved production. We also found that X13 substantially reduced the Cd2+ bioavailability for pak choi. Therefore, strain X13 is an effective treatment for potential application in Cd2+ remediation as well as for sustainable agronomic production programs in Cd-contaminated soils.