Biologically evolved dual-pathway catalytic pattern indicating an efficient bioremediation strategy for phenol removal

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Bioremediation of phenol has been developed for years, however, its actual application is challenged by low efficiency and environmental intolerance. In addition, although multiple phenol degradation pathways have been reported to coexist in bacteria, the potential significance and value have not been clearly revealed. Here, highly efficient phenol catalytic patterns were identified, and multi-pathway catalytic mechanism was investigated. Parageobacillus thermoglucosidasius W-36 employing a dual-pathway pattern exhibited superior degradation performance than P. thermoglucosidasius W-2 that employed a single-pathway pattern. An exogenous copy of degradation pathway in dual-pathway pattern was obtained via horizontal gene transfer. Based on homology modeling and molecular docking, the three-dimensional structures and substrate-binding sites of exogenous key enzymes were distinct from those of isofunctional enzymes encoded by the chromosome. The dual-pathway pattern was expressed in response to substrate levels in a time-dependent manner, indicating that synergistic effect of degradation pathways conferred strain adaptability to high-concentration phenol. Evolutionary analysis showed that the artful single/dual-pathway patterns in this species may be a natural selection phenomenon caused by high-concentration phenol. Collectively, this naturally evolved pattern enlightens the new strategy and feasibility of introducing auxiliary metabolic pathways to improve degradation efficiency of pollutants.