Bacterial Strain Pseudomonas Research Articles

Biodegradation of Endosulfan by Pseudomonas fluorescens

The endosulfan-degrading bacterial strain Pseudomonas fluorescens was isolated, and degradation of endosulfan by freely suspended and calcium-alginate entrapped bacterial cells were investigated in batch as well as in packed bed column studies. Freely suspended Pseudomonas fluorescens cells with biomass maximum OD/OD0 value of 1.68 at 610 nm could degrade endosulfan with an initial concentration of 350.24 ± 0.83 μg/L efficiently within 12 days, thus utilising endosulfan as the sole carbon and energy source. Degradation of endosulfan occurred concomitantly with bacterial growth. The bacteria immobilised in Ca-alginate beads in batch shake flask system were tested for their ability to degrade endosulfan at different concentrations (350.24 ± 0.83, 450.39 ± 1.95 and 550.85 ± 1.84 μg/L). A total of 125 mL of Broth minimal medium of pH 7 was inoculated with 5 g of wet Ca-alginate beads (derived from a 3-mL cell suspension of 0.72 OD at 610 nm) for the study. Almost similar trends of degradation efficiencies were shown by the immobilised cells toward different concentrations of endosulfan. The complete removal of alpha and beta-isomers of endosulfan at different initial endosulfan concentrations was observed between 9 and 11 days of the experiment. Additionally, the degradation rate in batch reactors with Ca-alginate-immobilised cells also derived from a 3-mL cell suspension of 0.72 OD at 610 nm was tested and found to be marginally higher than that of free cells. Ca-alginate immobilised cells in packed bed reactors operated in a semi-continuous mode could degrade toxic alpha and beta-isomers of endosulfan (350.38 ± 1.18 μg/L) within 6 days. Thus, the method proved effective for biodegradation of endosulfan. The metabolites formed indicated that the degradation of the pesticide follows a hydrolytic pathway.

Bioconversion of styrene to poly(hydroxyalkanoate) (PHA) by the new bacterial strain Pseudomonas putida NBUS12.

Styrene is a toxic pollutant commonly found in waste effluents from plastic processing industries. We herein identified and characterized microorganisms for bioconversion of the organic eco-pollutant styrene into a valuable biopolymer medium-chain-length poly(hydroxyalkanoate) (mcl-PHA). Twelve newly-isolated styrene-degrading Pseudomonads were obtained and partial phaC genes were detected by PCR in these isolates. These isolates assimilated styrene to produce mcl-PHA, forming PHA contents between 0.05±0.00 and 23.10±3.25% cell dry mass (% CDM). The best-performing isolate was identified as Pseudomonas putida NBUS12. A genetic analysis of 16S rDNA and phaZ genes revealed P. putida NBUS12 as a genetically-distinct strain from existing phenotypically-similar bacterial strains. This bacterium achieved a final biomass of 1.28±0.10 g L−1 and PHA content of 32.49±2.40% CDM. The extracted polymer was mainly comprised of 3-hydroxyhexanoate (C6 ), 3-hydroxyoctanoate (C8 ), 3-hydroxydecanoate (C10 ), 3-hydroxydodecanoate (C12 ), and 3-hydroxytetradecanoate (C14 ) monomers at a ratio of 2:42:1257:17:1. These results collectively suggested that P. putida NBUS12 is a promising candidate for the biotechnological conversion of styrene into mcl-PHA.

Effect of trace metals and electron shuttle on simultaneous reduction of reactive black-5 azo dye and hexavalent chromium in liquid medium by Pseudomonas sp.

This study demonstrates the role of electron shuttles and trace metals in the biotransformation of azo dye reactive black-5 and hexavalent chromium (CrVI) that are released simultaneously in tannery effluent. Previously isolated bacterial strain Pseudomonas putida KI was used for the simultaneous reduction of the dye (100mgL−1) and CrVI (2mgL−1) in a mineral salts medium (MSM). Among various trace metals, only Cu(II) had a stimulating effect on the bacterial-mediated reduction process. Application of electron shuttles such as hydroquinone and uric acid at a low concentration (1mM) had a positive effect on the reduction process and caused simultaneous reduction of 100% dye and 97% CrVI in 12–18h. Mannitol, EDTA and sodium benzoate at all concentrations (ranging from 1 to 9mM) showed an inhibitory effect on the reduction of reactive black-5 and CrVI. An inverse linear relationship between the velocity of reaction (V) and the concentration [S] of electron shuttles was observed. The results imply that both types and concentration of an electron shuttle and trace metals can affect the simultaneous reduction of reactive black-5 and CrVI.

Competitive antibacterial activity of two Indian major carps and two Chinese carps fish mucus against common pathogenic bacteria at aquaculture pond

A search for antibacterial activity of carp fish mucus was performed for different protein concentrations, against four different bacterial strains Aeromonas hydrophila, Aeromonas sorbia, Pseudomonas fluorescens and Vibrio anguillarum. Protein concentrations (3.40 mg/ml) in catla mucus samples were found higher than the protein concentrations (3.12 mg/ml) of rohu mucus samples when tested by Bicinchoninic assay (BCA). Antibacterial activity was detected in mucus samples of four carp fish species, against the four bacterial strains. The results of this study indicate that the mucus of carp fish contain one or several components (protein, beneficial bacteria and other chemical component) with antibacterial activity. These bioactive substances may play an important role in the ability of mucus to defend carp fish against pathogenic bacteria or microorganisms. However, more investigation is necessary to confirm the antibacterial activity in carp fish mucus at different protein concentration and to purify and characterize the active components.

Treatment of Textile Dyes by Bio-chemical Process in Stirred Tank Sequencing Batch Bioreactor (STSBBR)

A bacterial isolate Pseudomonas sp. was isolated from the solid waste slump collected from a local duping site of Sylhet district and was efficiently utilized for the removal of dye (Orange 3R) from simulated synthetic waste water in a lab scale Stirred Tank Sequencing Batch Bioreactor (STSBBR) in batch mode. A reactor with 2 L capacity (working volume 0.5 L) equipped with suitable control means and stirring mechanism was operated at room temperature and pH 6.6 ± 1 in fill-react-settling-draw mode with different initial dye concentrations (50, 100, 150, 200 & 300 ppm) where the hydraulic retention time was maintained for 12-72 hours depending on the adaptation of waste water by the bacterial strain. The efficiency of the reactor was analyzed with respect to three strands and found to be negative correlation with the concentration of the dye. Overall color, COD, and BOD in the Stirred tank bioreactor system (STSBBR) were removed by 49.67, 37.45 and 33.89%, respectively with 50 ppm dye concentration and HRT of 24 h. The efficiency of the reactor was found to be in negative correlation with the concentration of the dye. This STSBBR system was found very effective for efficient biological treatment of such dyeing industry waste water by the bacterial strain Pseudomonas sp. DOI: http://dx.doi.org/10.3329/jce.v27i2.17808 Journal of Chemical Engineering, IEB Vol. ChE. 27, No. 2, December 2012: 77-82

Long-term activity of biohybrid coatings of atrazine-degrading bacteria Pseudomonas sp. ADP

The atrazine-degrading bacterial strain Pseudomonas sp. ADP was immobilized by the sol–gel process within thin silica layers coated onto water-retaining carrier materials (expanded clay pellets and scoria). The performance of the obtained biohybrid material has been investigated concerning long-term activity under non-growth conditions. Experiments were run in phosphate buffer containing atrazine (20 mg l−1) as the sole source of carbon and nitrogen. Even after one year of consecutive batch tests, P. ADP immobilized onto expanded clay pellets showed a high atrazine degradation activity. In the course of long-term batch experiments, the average amount of removed atrazine was about 94% during each assay cycle. Staining with CTC revealed that in spite of cultivation under non-growth conditions over a period of one year, immobilized cells were still vital and showed respiratory activity.

Biodecolorization of reactive black-5 by a metal and salt tolerant bacterial strain Pseudomonas sp. RA20 isolated from Paharang drain effluents in Pakistan

Discharge of untreated azo dyes contaminated textile wastewater into soil and water bodies causes severe contamination. The present study was conducted to isolate dye degrading bacterial strains from a textile industry wastewater carrying drain in the neighborhood of Faisalabad, Pakistan. Seventy six bacterial strains were initially isolated and was screened using liquid mineral salts medium spiked with Reactive Black-5 azo dye. The strain RA20 was found to be the most efficient azo dye degrading bacterial isolate and was identified by amplifying and sequencing its 16S rRNA. Analysis indicated that this strain belonged to genus Pseudomonas and was designated as Pseudomonas sp. RA20. It had the highest decolorization activity at pH 8 and 25°C incubation temperature under static conditions using yeast extract as an additional C source. This strain was also effective in decolorizing structurally related other reactive dyes including Reactive Orange 16, Reactive Yellow 2 and Reactive Red 120 but with varying efficacy. RA20 decolorized Reactive Black-5 significantly in the presence of up to 30gL−1 NaCl; however, the decolorization rate was significantly (p≤0.05) reduced beyond this salt concentration. Moreover, this bacterial strain also exhibited moderate tolerance to different heavy metals including zinc (Zn), cadmium (Cd), chromium (Cr), lead (Pb) and copper (Cu). RA20 also decolorized Reactive Black-5 in the presence of a mixture of the selected heavy metals depending upon their concentrations. This study highlights the importance of Pseudomonas sp. RA20 as a prospective biological resource for bioremediation of water and soils contaminated with azo dyes.

Maize development and grain quality are differentially affected by mycorrhizal fungi and a growth-promoting pseudomonad in the field

Arbuscular mycorrhizal (AM) fungi and plant growth-promoting bacteria (PGPB) can increase the growth and yield of major crops, and improve the quality of fruits and leaves. However, little is known about their impact on seed composition. Plants were inoculated with AM fungi and/or the bacterial strain Pseudomonas fluorescens Pf4 and harvested after 7months of growth in open-field conditions. Plant growth parameters were measured (biomass, length and circumference of spikes, number of grains per cob, grain yield, and grain size) and protein, lipid, and starch content in grains were determined. Plant growth and yield were increased by inoculation with the microorganisms. Moreover, spikes and grains of inoculated plants were bigger than those produced by uninoculated plants. Regarding grain composition, the bacterial strain increased grain starch content, especially the digestible components, whereas AM fungi-enhanced protein, especially zein, content. Plant inoculation with the fluorescent pseudomonad and mycorrhizal fungi resulted in additive effects on grain composition. Overall, results showed that the bacterial strain and the AM fungi promoted maize growth cultivated in field conditions and differentially affected the grain nutritional content. Consequently, targeted plant inoculation with beneficial microorganisms can lead to commodities fulfilling consumer and industrial requirements.

Antibacterial characteristics of electroless plating Ni–P–TiO2 coatings

Electroless Ni–P coatings have been widely used in the chemical, mechanical and electronic industries due to their excellent corrosion and wear resistance. Many studies reported that the incorporation of nano-sized particles TiO2 into Ni–P matrix greatly improved their anti-corrosion and anti-wear resistance. However no studies have been reported on their anti-bacterial property. In this paper, the Ni–P–TiO2 nano-composite coatings were prepared on stainless steel 316L using electroless plating technique. The experimental results showed that the Ni–P–TiO2 coatings reduced the adhesion of three bacterial strains (Pseudomonas fluorescens, Cobetia and Vibrio) by up to 75% and 70% respectively, as compared with stainless steel and Ni–P coatings. The electron donor surface energy of the Ni–P–TiO2 coatings increased significantly with increasing TiO2 content after UV irradiation. The number of adhered bacteria decreased with increasing electron donor surface energy of the coatings.

Response surface Optimization for Biodegradation of Textile Azo dyes using isolated bacterial strain Pseudomonas sp.

Response surface methodology was applied to optimize the process inducers for the biodegradation of textile azo dyes containing Congo red and Reactive red 195 with isolated strain Pseudomonas sp. Three important process inducers: initial concentration (20–100 mg/L), carbon source (0–2 g/L) and nitrogen source (0–2 g/L) were successfully employed for the optimization of biodegradation process using central composite design matrix. According to the analysis of variance (ANOVA) results, the predicted results were found to be in good agreement with experimental results (R2: 0.9695; Adj. R2: 0.9421) which indicated excellent evaluation of experimental data by second-order polynomial regression model. Mathematical model was developed by the proposed system, for each process variables and showed the effect of each factor and their interactions on biodegradation process. The optimum concentrations of dye, carbon source, and nitrogen source were found to be 40 mg/L, 1.5 g/L and 1.5 g/L, respectively, for Congo red and 20 mg/L, 1.0 g/L and 1.0 g/L, respectively, for Reactive red 195. Predicted values were validated with experimental values, which indicated appropriateness of the employed model and the success of RSM. HPLC and FTIR analysis confirmed biodegradation.

Nonadhesive, silica nanoparticles-based brush-coated contact lens cases-Compromising between ease of cleaning and microbial transmission to contact lenses

Surface properties of lens cases are determinant for their cleanability and for microbial transmission from lens cases to contact lenses (CLs). PEG-polymer-brush-coatings are known to decrease microbial adhesion more than other surface-coatings. Here, we applied a robust, silica nanoparticles-based brush-coating to polypropylene cases to evaluate their ease of cleaning and probability of bacterial transmission to CLs. Adhesion forces of nine bacterial strains (Pseudomonas, Staphylococci, and Serratia) to rigid CLs, polypropylene, and silica nanoparticles-based brush-coated polypropylene were measured using atomic-force-microscopy and subjected to Weibull analyses to yield bacterial transmission probabilities. Biofilms of each strain were grown in coated and uncoated cases and rinsed with a NaCl or antimicrobial lens care solution. Residual, viable organisms were quantified. Bacterial adhesion forces of all strains were significantly, up to tenfold smaller on brush-coated than on uncoated polypropylene. This yielded, higher transmission probabilities to a CL, but mild-rinsing yielded 10-100 fold higher removal of bacteria from brush-coated than from polypropylene cases. Moreover, due to weak adhesion forces, bacteria on brush-coated cases were two-to-three fold more susceptible to an antimicrobial lens care solution than on polypropylene cases. Therewith, the design of lens case surfaces is a compromise between ease of cleaning and transmission probability to CLs.

Purification and characterization of exo-β-agarase from an endophytic marine bacterium and its catalytic potential in bioconversion of red algal cell wall polysaccharides into galactans

An extracellular exo-β-agarase was characterized from an endophytic bacterial strain Pseudomonas sp. isolated from the red alga Gracilaria dura. The enzyme was purified to homogeneity with a recovery of 28.2% and a purity fold of 8.33. The purified enzyme was composed of single polypeptide with a molecular mass of about 66 kDa. The enzyme exhibited a maximum activity of 81.74 U mL−1 and a specific activity of 615.5 U mg−1. The optimal pH and temperature for its maximum activity were 9.0 and 35 °C respectively. The enzyme stabilized its activity in alkaline pH 7–11 and high salt concentration up to 4 mol dm−3. The enzymatic hydrolyzed product of agar was characterized as neoagarobiose while the bacterium when incubated with G. dura biomass yielded galactose 20% on dry wt basis. The agarolytic ability of the former was further confirmed by release of protoplasts from G. dura tissue through digestion of cell wall polysaccharides. The bacterium investigated in this study could possibly be used for bioconversion of marine red algal polysaccharides into energy feedstock and the purified enzyme for preparation of compounds having pharmaceutical importance.

Effect of 1-aminocyclopropane-1-carboxylic acid deaminase producing bacteria on the hyphal growth and primordium initiation of Agaricus bisporus

Abstract The mechanism of casing soil stimulating the primordium formation of Agaricus bisporus is not well understood so far. Our results showed that 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (AcdS)-producing bacteria were abundant in the casing soil of A. bisporus and accounted for up to 20 % of total culturable bacteria. A. bisporus produced ACC and ethylene. The supplement of methionine increased the ACC concentrations within the hyphae, and aminooxyacetic acid displayed an opposite effect. Methionine and ACC promoted the ethylene production while CoCl 2 suppressed the production. The AcdS-producing bacterial strain Pseudomonas putida UW4 co-cultured with A. bisporus could attach to hyphae, stimulate the hyphal growth, and reduce the ethylene production of A. bisporus . Added in sterilized casing soil, it induced the primordium formation of A. bisporus . In comparison, its AcdS-deficient mutant UW4-AcdS − displayed the opposite effects. These results indicated that the inhibitor to the primordium formation of A. bisporus was ethylene; the AcdS-producing bacteria within the casing layer cleaved ACC, lowered the ethylene level in mushroom hyphae, and relieved the inhibition of ethylene. This is a new model of the synergism between bacteria and fungi.

Prospectus of phosphate solubilizing microorganisms and phosphorus availability in agricultural soils: A review

Phosphate solubilizing microorganisms (PSMs) offer an ecologically acceptable mean for converting insoluble phosphate to soluble forms making them available for plants to absorb. Several bacterial strains (Pseudomonas, Bacillus, Rhizobium and Enterobacter) and fungal strains (Aspergillus and Penicillium) have so far been recognized as powerful phosphate solubilizers. Insoluble phosphates are converted into available forms by phosphate solubilizing microorganisms via the process of acidification, chelation, exchange reactions and production of organic acid. Though phosphorus is found to be a limiting factor in many soils, application of PSMs as biofertilizers or bioconverters for solubilizing fixed phosphorus has not yet been successfully practiced. In this context, isolation, identification and characterization of soil PSMs are considered to be effective in broadening the spectrum of phosphate solubilizers available for field application. Key words: Phosphate solubilization, insoluble phosphate, organic acid, Phosphate solubilizing microorganisms (PSMs).

Chemical composition and antibacterial and antioxidant properties of commercial essential oils

The aim of this work was to determine the effectiveness of 17 essential oils to inhibit the growth of seven food-borne spoilage and pathogenic bacterial strains (Brochothrix thermosphacta, Escherichia coli, Listeria innocua, Listeria monocytogenes, Pseudomonas putida, Salmonella typhimurium and Shewanella putrefaciens). Additionally, the antioxidant activity (by free radical scavenging activity and ferric reducing power) and the chemical composition of these essential oils were evaluated. All essential oils inhibited the growth of at least four bacteria tested, and lower values of minimum inhibitory concentration (<3.0mgmL−1) were needed to inhibit P. putida. The highest reductions (8.0logCFUmL−1) were achieved with coriander, origanum and rosemary essential oils for L. innocua, as well as with thyme essential oil for both Listeria strains. The results showed that for the evaluation of antibacterial activity of plant essential oils, bacterial counts should be performed instead of absorbance readings when using microdilution methods. Regarding the antioxidant activity, clove and origanum essential oils showed the strongest antioxidant properties. Essential oils showed a great variety of compounds in their chemical compositions, some of those with known antibacterial and antioxidant properties. In conclusion, all tested essential oils have very strong potential applicability as antibacterial and antioxidant agents for food and pharmaceutical industries.

Characterization of siderophore producing bacterial strain Pseudomonas fluorescens Mst 8.2 as plant growth promoting and biocontrol agent in wheat

A set of 28 Pseudomonas bacterial strains were examined for siderophore production by chrome azurol sulphonate (CAS) assay. Among the 28 strains tested, 14 were found to be siderophore producers. These strains were evaluated for their biocontrol potential againstRhizoctonia solani using various dual culture assays. The role of siderophores in the inhibition of R. solani was confirmed by iron chloride (FeCl3) experiment. The eight strains that showed best antagonism were found to have the potential of nitrogen fixation, phosphate solubilization, indole acetic acid, hydrolytic enzymes, hydrogen cyanide and antibiotics production. Spectrochemical analysis of siderophores indicated that all the bacterial strains produce catecholate siderophores. Our data demonstrated that bacterial strain Mst 8.2 produces more than one antifungal agents but the siderophore production is the key mechanism involved in the antagonism. Bacterial strains MS-3y, Mst 8.2 and Mst 7.4 were the most effective with more than 70% disease reduction in plant growth of wheat. The complete 16S rRNA gene sequence analysis demonstrated that Mst 8.2 is aPseudomonas fluorescens strain. In conclusion, Mst 8.2 with its multi-mechanisms of defense has excellent potential to be used as successful biocontrol agent against R. solani root rot disease in wheat. Key words: Bioantagonism, rhizobacteria, Pseudomonas, wheat, siderophore.

Response surface optimization for efficient dye removal by isolated strain Pseudomonas sp.

Abstract Response surface methodology (RSM) involving the central composite design (CCD) was employed to optimize three important process variables for the decolourization of synthetic dye solutions containing Remazol Turquoise Blue (RTB) and Reactive Black 5 (RB5) with isolated bacterial strain Pseudomonas sp. The interaction between three variables i.e. Initial concentration of dye, carbon source and nitrogen source were studied and modeled. According to the Analysis of variance (ANOVA) results the predicted results were found to be in good agreement with experimental results (R 2: 0.9726; Adj R 2: 0.9480 for RTB and R 2: 0.9789; Adj R 2: 0.9750 for RB5) which indicated excellent evaluation of experimental data from the second order polynomial regression model. Mathematical models were developed by the proposed system, for each process variable showed the effect of each factor and their interactions on biodecolourization process. The optimum concentrations of Dye, Carbon source, and Nitrogen source were found to be 20 mgL−1, 1.5 g/L and 1.5 g/L, respectively for RTB and RB5 to obtain maximum dye removing capacity. Predicted values were validated with experimental results, which indicated appropriateness of the employed model and the success of RSM.

Antibacterial activity of leaf extracts of some selected traditional medicinal plants of Uttarakhand, North East India

Screenings of methanolic leaf extracts of nine medicinal plants (Cotinus coggygria, Adhatoda vesica, Argemone mexicana, Zanthoxylum armatum, Berberis asiatica, Corissa opaca, Euphorbia hirta, Cassio fistula and Ricinus communis), belonging to selected areas of Uttarakhand, were tested against seven bacterial strains (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Enterobactor aerogenes, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa) by disc diffusion method. Leaf extracts of R. communis, B. asiatica and C. opaca showed high (13 – 23) effect on all the bacterial strains while E. hirta, Z. armatum and A. vesica exhibits minimum (6 – 15) effects. Remaining leaf extracts of plants were found moderately (10 - 19) effective.

Characterization of the nitrobenzene-degrading strain Pseudomonas sp. a3 and use of its immobilized cells in the treatment of mixed aromatics wastewater

A bacterial strain Pseudomonas sp. a3 capable of degrading nitrobenzene, phenol, aniline, and other aromatics was isolated and characterized. When nitrobenzene was degraded, the release of NH(4) (+) was detected, but not of NO(2) (-). This result implied that nitrobenzene might have a partial reductive metabolic pathway in strain a3. However, aniline appeared as one of the metabolites during the aerobic degradation of nitrobenzene. Moreover, the appearance of 2-aminophenol during aniline degradation by strain a3 indicated that novel initial reactions existed during the degradation of nitrobenzene and aniline by strain a3. Strain a3 was immobilized in the mixed carrier of polyvinyl alcohol and sodium alginate to improve its degrading efficiency. The optimal concentrations of polyvinyl alcohol and sodium alginate in the mixed carrier were 9 and 3 %, respectively. The immobilized cells had stable degradation activity and good mechanical properties in the recycling tests. The immobilized cells also exhibited higher tolerances in acidic (pH 4-5) and highly saline (10 % NaCl) environments than those of free cells. The biodegradation of nitrobenzene mixed with aniline and phenol using immobilized cells of Pseudomonas sp. a3 was also greatly improved compared with those of free cells. The immobilized cells could completely degrade 300 mg L(-1) nitrobenzene within 10 h with 150 mg L(-1) aniline and 150 mg L(-1) phenol. This result revealed that the immobilized cells of Pseudomonas sp. a3 could be a potential candidate for treating nitrobenzene wastewater mixed with other aromatics.

Bioremediation of Cd and carbendazim co-contaminated soil by Cd-hyperaccumulator Sedum alfredii associated with carbendazim-degrading bacterial strains

The objective of this study was to develop a bioremediation strategy for cadmium (Cd) and carbendazim co-contaminated soil using a hyperaccumulator plant (Sedum alfredii) combined with carbendazim-degrading bacterial strains (Bacillus subtilis, Paracoccus sp., Flavobacterium and Pseudomonas sp.). A pot experiment was conducted under greenhouse conditions for 180 days with S. alfredii and/or carbendazim-degrading strains grown in soil artificially polluted with two levels of contaminants (low level, 1 mg kg(-1) Cd and 21 mg kg(-1) carbendazim; high level, 6 mg kg(-1) Cd and 117 mg kg(-1) carbendazim). Cd removal efficiencies were 32.3-35.1 % and 7.8-8.2 % for the low and high contaminant level, respectively. Inoculation with carbendazim-degrading bacterial strains significantly (P < 0.05) increased Cd removal efficiencies at the low level. The carbendazim removal efficiencies increased by 32.1-42.5 % by the association of S. alfredii with carbendazim-degrading bacterial strains, as compared to control, regardless of contaminant level. Cultivation with S. alfredii and inoculation of carbendazim-degrading bacterial strains increased soil microbial biomass, dehydrogenase activities and microbial diversities by 46.2-121.3 %, 64.2-143.4 %, and 2.4-24.7 %, respectively. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis revealed that S. alfredii stimulated the activities of Flavobacteria and Bradyrhizobiaceae. The association of S. alfredii with carbendazim-degrading bacterial strains enhanced the degradation of carbendazim by changing microbial activity and community structure in the soil. The results demonstrated that association of S. alfredii with carbendazim-degrading bacterial strains is promising for remediation of Cd and carbendazim co-contaminated soil.