Biodegradation of p-nitrophenol sorbed onto crystal violet-modified organoclay by Arthrobacter sp. 4Hβ

Appl Microbiol Biotechnol. 2014 Feb;98(3):1321-7. doi: 10.1007/s00253-013-4999-2. Epub 2013 May 30.


Organoclays are effective sorbents for removal of organic contaminants from water, but their regeneration capacity limits their practical use as a biotechnological process for bioremediation. Here, the sorption of p-nitrophenol (PNP) to crystal violet (CV)-modified montmorillonite and its biodegradation by the bacterium Arthrobacter sp. 4Hβ were studied in a batch aqueous system. The degree of PNP sorption was dependent on the degree of CV modification (loaded at 80 % or 100 % of the clay's cation-exchange capacity-CVM80 and CVM100, respectively). CV sorption to the clay reduced its toxicity to bacteria. PNP at an initial concentration of 0.72 mM was degraded at rates of 65 % and 42 % in CVM80 and CVM100 suspensions, respectively. Both free and CV-clay-adsorbed PNP concentrations were reduced by the bacteria at rates proportional to the degree of CV modification. Three successive cycles of PNP reloading-degradation in the organoclay suspension demonstrated the potential of this matrix's regeneration and reuse toward maximal removal efficiency of organic pollutants.

MeSH terms

  • Adsorption*
  • Aluminum Silicates / chemistry*
  • Arthrobacter / metabolism*
  • Clay
  • Gentian Violet
  • Nitrophenols / metabolism*
  • Water Purification / methods


  • Aluminum Silicates
  • Nitrophenols
  • Gentian Violet
  • Clay
  • 4-nitrophenol