Biodegradation of Benzophenone-3 in Non-Sterile Culture Process Using <i>Klebsiella huaxiensis</i> W2

Benzophenone-3 (BP3) is an organic pollutant widely detected in soil and aquatic environments. The aims of this study were to isolate a bacterium which is capable of degrading BP3 and converting it into non-toxic products, and to design a non-sterile culture process which may be applied to the real biological treatment systems for the bioremediation of BP3. Klebsiella huaxiensis W2 (GenBank accession number: PQ143284) isolated from a wastewater treatment system was found to have high potency to degrade BP3. This bacterium degraded BP3 into two byproducts: phenol, 2,4-bis-(1,1-dimethylethyl) and benzyl benzoate. Oxygenases (P450 monooxygenases, dioxygenases etc.) were predicted to be effective in BP3 degradation. BP3-degradation products did not cause a toxicity on fibroblast cell line. Optimizing inoculum size, that is, inoculating the high size (1-2%) of the bacterial preculture into the wastewater-based medium, make the bacterium more dominant in this medium, thus enabling the bacterial cells to degrade BP3 under non-sterile culture conditions. In this process, biodegradation efficiency was not affected notably from temperature variations, and the bacterium was able to hydrolyze about 99.33% of 1 g/L BP3 within 120 h. Overall, K. huaxiensis W2 was deduced to possess the potency for being used as a bioremediation agent in non-sterile biological treatment systems, in which sterilization process, temperature control, and nutrient supplementation were not needed. The designed process may find applications in the bioremediation of wastewater and sewage effluents. This is the first study using K. huaxiensis in a non-sterile environment for BP3 degradation.