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Enhanced biodegradation of atrazine by bacteria encapsulated in organically modified silica gels.

Authors
  • Benson, Joey J1
  • Sakkos, Jonathan K1
  • Radian, Adi2
  • Wackett, Lawrence P3
  • Aksan, Alptekin4
  • 1 Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA; BioTechnology Institute, University of Minnesota, St Paul, MN 55108, USA.
  • 2 BioTechnology Institute, University of Minnesota, St Paul, MN 55108, USA; Department of Environmental, Water and Agricultural Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel. , (Israel)
  • 3 BioTechnology Institute, University of Minnesota, St Paul, MN 55108, USA; Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
  • 4 Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA; BioTechnology Institute, University of Minnesota, St Paul, MN 55108, USA. Electronic address: [email protected]
Type
Published Article
Journal
Journal of Colloid and Interface Science
Publisher
Elsevier
Publication Date
Jan 15, 2018
Volume
510
Pages
57–68
Identifiers
DOI: 10.1016/j.jcis.2017.09.044
PMID: 28934611
Source
Medline
Keywords
License
Unknown

Abstract

Biodegradation by cells encapsulated in silica gel is an economical and environmentally friendly method for the removal of toxic chemicals from the environment. In this work, recombinant E. coli expressing atrazine chlorohydrolase (AtzA) were encapsulated in organically modified silica (ORMOSIL) gels composed of TEOS, silica nanoparticles (SNPs), and either phenyltriethoxysilane (PTES) or methyltriethoxysilane (MTES). ORMOSIL gels adsorbed much higher amounts of atrazine than the hydrophilic TEOS gels. The highest amount of atrazine adsorbed by ORMOSIL gels was 48.91×10-3μmol/mlgel, compared to 8.71×10-3μmol/mlgel by the hydrophilic TEOS gels. Atrazine biodegradation rates were also higher in ORMOSIL gels than the TEOS gels, mainly due to co-localization of the hydrophobic substrate at high concentrations in close proximity of the encapsulated bacteria. A direct correlation between atrazine adsorption and biodegradation was observed unless biodegradation decreased due to severe phase separation. The optimized PTES and MTES gels had atrazine biodegradation rates of 0.041±0.003 and 0.047±0.004μmol/mlgel, respectively. These rates were approximately 80% higher than that measured in the TEOS gel. This study showed for the first time that optimized hydrophobic gel material design can be used to enhance both removal and biodegradation of hydrophobic chemicals.

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