Silica gel-encapsulated AtzA biocatalyst for atrazine biodegradation

Eduardo Reátegui, Erik Reynolds, Lisa Kasinkas, Amit Aggarwal, Michael J. Sadowsky, Alptekin Aksan, Lawrence P. Wackett

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

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 languageEnglish (US)
Pages (from-to)231-240
Number of pages10
JournalApplied Microbiology and Biotechnology
Volume96
Issue number1
DOIs
StatePublished - Oct 1 2012

Keywords

  • Atrazine
  • AtzA
  • Bacteria
  • Biodegradation
  • E. coli
  • Silica

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