Enhancing the biodegradation of 4-chlorophenol by Arthrobacter chlorophenolicus A6 via medium development

This study reports development of a suitable medium for enhancing the 4-chlorophenol (4-CP) biodegradation by Arthrobacter chlorophenolicus A6 employing sequential design of experiments. The media constituents were initially screened using a 2-level factorial design, and the results indicated that dipotassium hydrogen phosphate, ammonium nitrate, magnesium sulfate and calcium chloride significantly influence both 4-CP biodegradation and growth of the culture. Among these significant factors only calcium chloride showed a large positive effect on 4-CP biodegradation by the microorganism. While dipotassium hydrogen phosphate also showed slightly positive effect on the culture specific growth rate, it, however, exhibited some negative effect on 4-CP biodegradation efficiency. Both magnesium sulfate and ammonium nitrate in the media negatively influenced both 4-CP biodegradation as well as the culture specific growth rate. A central composite design of experiments was further used to optimize the levels of the screened media constituents for enhancing the 4-CP biodegradation efficiency. The results revealed 100% 4-CP biodegradation efficiency with a maximum specific growth rate of 0.093 h−1 at an optimum combination of 2.62 g l−1 of dipotassium hydrogen phosphate, 0.58 g l−1 of ammonium nitrate, 0.17 g l−1 of magnesium sulfate and 0.04 g l−1 of calcium chloride in the medium.