Biodegradation of 4-Chlorobenzoic Acid by Lysinibacillus macrolides DSM54T and Determination of Optimal Conditions

Chlorobenzoic acids (CBAs) are recalcitrant and toxic materials which enter the environment directly using pesticides and herbicides, or indirectly through the biodegradation of polychlorinated biphenyl (PCB) compounds. In the conducted study, biodegradation of 4-chlrobenzoic acid was investigated by Lysinibacillus macrolides DSM54T, which had previously been isolated from PCB-polluted soils. Environmental factors including pH, temperature, 4-CBA concentration and inoculation percentage were optimized using response surface methodology (RSM). 58 experiments were designed according to Historical Data, because of the arbitrary selection of experiments, and the combined effects of the independent variables were investigated through the cubic model (P < 0.0001). Degradation percentage of 4-CBA was measured by gas chromatography/mass spectroscopy. One hundred percent removal of 4-CBA was statistically estimated after 96 h at the best environmental conditions, which were pH = 5.25, temperature = 32.75 (degrees C), 4-CBA concentration = 237.17 (ppm), and inoculation percentage = 18.32 (%V/V). The inoculation percentage was the most effective parameter on the biodegradation of 4-CBA (P < 0.0001), while, the temperature had the least impact (P = 0.7340). High removal efficiency (93.45% in practice and 100% in theory) proved that the examined strain could be a promising candidate for bioremediation of chlorobenzoic acids from polluted soils.