Can Xenobiotics Support the Growth of Mn(Ii)-Oxidizing Bacteria (Mnob)? A Case of Phenol-Utilizing Mnob Pseudomonas Sp. An-1

Biogenic manganese oxides (BioMnOx) produced by Mn(II)-oxidizing bacteria (MnOB) have attracted much attention due to their superior adsorption and oxidation capacity. However, these studies only focused on the role by BioMnOx and rarely concerned on MnOB themselves. Meanwhile, whether the xenobiotics could support the growth of MnOB as the sole carbon source is still unclear. In this study, we isolated a strain termed Pseudomonas sp. AN-1, which could use phenol as the sole carbon source. The degradation of phenol took precedence over the accumulation of BioMnOx. In the presence of 100 mg L-1 phenol and 100 µM Mn(II), phenol was entirely degraded at 20 h and Mn(II) was entirely oxidized at 30 h. At the higher phenol concentration (500 mg L-1), phenol degradation reduced to 32% and Mn(II) oxidation was apparently not occurred. TOC determination demonstrated that strain AN-1 could mineralize phenol. Based on the genomic and proteomics study, the Mn(II) oxidation and phenol mineralization mechanism of strain AN-1 was further confirmed, and carbon-source concentration modulated expression of Mn(II)-oxidation proteins were first found. This work provides new insight into the interaction between xenobiotics and MnOB, thus revealing the complexity of biogeochemical cycles of Mn and C.