Toxicity and biodegradation of ibuprofen by Bacillus thuringiensis B1(2015b)

Abstract

In recent years, the increased intake of ibuprofen has resulted in the presence of the drug in the environment. This work presents results of a study on degradation of ibuprofen at 25 mg L−1 in the presence of glucose, as an additional carbon source by Bacillus thuringiensis B1(2015b). In the cometabolic system, the maximum specific growth rate of the bacterial strain was 0.07 ± 0.01 mg mL−1 h−1 and Ksμ 0.27 ± 0.15 mg L−1. The maximum specific ibuprofen removal rate and the value of the half-saturation constant were qmax = 0.24 ± 0.02 mg mL−1 h−1 and Ks = 2.12 ± 0.56 mg L−1, respectively. It has been suggested that monooxygenase and catechol 1,2-dioxygenase are involved in ibuprofen degradation by B. thuringiensis B1(2015b). Toxicity studies showed that B. thuringiensis B1(2015b) is more resistant to ibuprofen than other tested organisms. The EC50 of ibuprofen on the B1 strain is 809.3 mg L−1, and it is 1.5 times higher than the value of the microbial toxic concentration (MTCavg). The obtained results indicate that B. thuringiensis B1(2015b) could be a useful tool in biodegradation/bioremediation processes.