Elucidation of 2, 4-Dichlorophenol degradation by Bacillus licheniformis strain SL10

2,4-Dichlorophenol (2,4-DCP) is a priority pollutant according to US Environmental Protection Agency. Its use in various chemical industries and its presence in the effluent necessitate effective removal studies. The present study focuses on degradation of 2,4-DCP by phenol adapted bacteria Bacillus licheniformis strain SL10 (MTCC 25059) at a relatively faster rate. The organism exhibited tolerance to 150 ppm of 2,4-DCP and showed a linear relationship between the growth and substrate concentration (mu(max) 0.022/h) and the inhibitory concentration was 55.74 mg/L. The degradation efficiency of the organism was 74% under optimum conditions but increased to 97% when the growth medium containing nil sodium chloride. The degradation of 2,4-DCP was effected by the action of extracellular cocktail enzyme containing Catechol 2, 3 dioxygenase (C23DO), phenol hydroxylase and Catechol, 1,2 dioxygenase (C12DO). In vitro enzymatic degradation studies exhibit 98% degradation of 50 ppm of 2,4-DCP within 2 h. Analyses of degradation products infer that the chosen organism followed a meta-cleavage pathway while degrading 2,4-DCP. In conclusion, the bacteria Bacillus licheniformis strain SL10 finds potential application in the remediation of 2,4-DCP.