Abstract
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.
Original language | English (US) |
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Pages (from-to) | 231-240 |
Number of pages | 10 |
Journal | Applied Microbiology and Biotechnology |
Volume | 96 |
Issue number | 1 |
DOIs | |
State | Published - Oct 2012 |
Bibliographical note
Funding Information:Acknowledgements We thank Mr. Baris Mutlu for his help in conducting experiments. This research was supported by a National Science Foundation grant (CBET-0644784) to AA, a research grant from Syngenta Crop Protection to LW, MS, and AA, and a seed grant to AA and LW from the BioTechnology Institute at University of Minnesota.
Keywords
- Atrazine
- AtzA
- Bacteria
- Biodegradation
- E. coli
- Silica