Enhancement of Atrazine Removal by Free and Immobilized<i>Arthrobacter</i>Sp. HB-5 in Soil and Wastewater

Zhu, Lusheng; Ma, Tingting; Wang, Jinhua; Xie, Hui; Wang, Jun; Xin, Chengyou

doi:10.1080/15320383.2011.528466

Cited by 12 publications

(1 citation statement)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Successful applications of atrazine bioremediation at high concentrations (samples from farm run-off waters or buffer solutions fortied with atrazine), from 10 to 30 ppm, have been reported [19][20][21][22] but most laboratory studies have used much higher atrazine concentrations that do not mimic actual environmental situations. Galindez-Najera et al reported complete removal (i.e.…”

Section: Introductionmentioning

confidence: 99%

Silicon alkoxide cross-linked silica nanoparticle gels for encapsulation of bacterial biocatalysts

et al. 2013

View full text Add to dashboard Cite

A method is developed for encapsulation of bacterial biocatalysts in silica gels formed by silica nanoparticles (SNP) and a silicon alkoxide crosslinker. Formulation of the gel was optimized by changing the SNP size, SNP to crosslinker ratio and crosslinker functionality. Hydrolysis and condensation reactions of silicon alkoxide were controlled by water to alkoxide ratio (r) and pH of the solution. FTIR analysis verified that a reactive and temporally stable silicon alkoxide crosslinker was obtained. As a case study, recombinant Escherichia coli (E. coli) cells expressing the atrazine dechlorinating enzyme AtzA were encapsulated. Synthesized catalytic biomaterials (silica gel encapsulated bacterial biocatalysts) were evaluated based on their gelation time, biocatalytic activity and mechanical strength. Diffusivity assays and SEM were used for characterization of the gel structure. We found that SNP to crosslinker ratio affected all the features of the gel, whereas crosslinker functionality primarily affected the gelation time and SNP size affected the mechanical strength and diffusivity. Based on systematic evaluation, we selected three gel formulations and subjected them to long-term activity measurements in a continuous-flow bioreactor for removing trace levels of atrazine. The effluent atrazine concentration was sustained below 30% of the influent concentration, <3 ppb, for 2 months.

show abstract

Section: Introductionmentioning

confidence: 99%

Silicon alkoxide cross-linked silica nanoparticle gels for encapsulation of bacterial biocatalysts

et al. 2013

View full text Add to dashboard Cite

show abstract

The combined stress effects of atrazine and cadmium on the earthworm Eisenia fetida

Wang¹,

Zhu²,

Meng³

et al. 2012

Enviro Toxic and Chemistry

Self Cite

View full text Add to dashboard Cite

To assess the combined toxic effects of atrazine and cadmium on earthworms, specimens of Eisenia fetida were exposed in artificial soil to three concentrations of atrazine (0, 0.5, and 2.5 mg kg(-1)) and a range of concentrations of cadmium (Cd; 0, 0.03, 0.3, and 3.0 mg kg(-1)) both singly and as mixtures. The DNA damage and internal atrazine and cadmium concentrations were assessed in earthworms on days 7, 14, 21, and 28 of the treatment. The results showed that the olive tail moments (OTMs) at individual atrazine and cadmium concentrations were significantly higher than those of the controls (p < 0.01). As exposure to atrazine or cadmium progressed, the OTMs increased and the maximum value occurred on day 28. In all combined treatments, the OTMs were much less than those of the sum of individual atrazine and cadmium OTMs, suggesting that the combined effects of atrazine and cadmium were less than additive. The less than additive toxicity of atrazine and cadmium might be due to the formation of atrazine-cadmium complexes or the activation of detoxification isozymes. Moreover, there was a significant correlation between internal atrazine or cadmium concentrations and DNA damage in most exposures, indicating that body residues were consistent with toxicity response.

show abstract

Silica gel-encapsulated AtzA biocatalyst for atrazine biodegradation

Reátegui

Reynolds

Kasinkas

et al. 2012

Appl Microbiol Biotechnol

View full text Add to dashboard Cite

Encapsulation of recombinant Escherichia coli cells expressing a biocatalyst has the potential to produce stable, long-lasting enzyme activity that can be used for numerous applications. The current study describes the use of this technology with recombinant E. coli cells expressing the atrazine-dechlorinating enzyme AtzA in a silica/polymer porous gel. This novel recombinant enzyme-based method utilizes both adsorption and degradation to remove atrazine from water. A combination of silica nanoparticles (Ludox TM40), alkoxides, and an organic polymer was used to synthesize a porous gel. Gel curing temperatures of 23 or 45 °C were used either to maintain cell viability or to render the cells non-viable, respectively. The enzymatic activity of the encapsulated viable and non-viable cells was high and extremely stable over the time period analyzed. At room temperature, the encapsulated non-viable cells maintained a specific activity between (0.44 ± 0.06) μmol/g/min and (0.66 ± 0.12) μmol/g/min for up to 4 months, comparing well with free, viable cell-specific activities (0.61 ± 0.04 μmol/g/min). Gels cured at 45 °C had excellent structural rigidity and contained few viable cells, making these gels potentially compatible with water treatment facility applications. When encapsulated, non-viable cells were assayed at 4 °C, the activity increased threefold over free cells, potentially due to differences in lipid membranes as shown by FTIR spectroscopy and electron microscopy.

show abstract

Enhancement of Atrazine Removal by Free and ImmobilizedArthrobacterSp. HB-5 in Soil and Wastewater

Cited by 12 publications

References 25 publications

Silicon alkoxide cross-linked silica nanoparticle gels for encapsulation of bacterial biocatalysts

Silicon alkoxide cross-linked silica nanoparticle gels for encapsulation of bacterial biocatalysts

The combined stress effects of atrazine and cadmium on the earthworm Eisenia fetida

Silica gel-encapsulated AtzA biocatalyst for atrazine biodegradation

Contact Info

Product

Resources

About