AUTHOR=Zheng Yanjing , Li Yumei , Long Hongyan , Zhao Xiaojuan , Jia Keke , Li Juan , Wang Leyong , Wang Ruiyong , Lu Xiancai , Zhang Dongmei 

TITLE=bifA Regulates Biofilm Development of Pseudomonas putida MnB1 as a Primary Response to H2O2 and Mn2+

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01490

DOI=10.3389/fmicb.2018.01490

ISSN=1664-302X

ABSTRACT=<p><italic>Pseudomonas putida</italic> (<italic>P. putida</italic>) MnB1 is a widely used model strain in environment science and technology for determining microbial manganese oxidation. Numerous studies have demonstrated that the growth and metabolism of <italic>P. putida</italic> MnB1 are influenced by various environmental factors. In this study, we investigated the effects of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and manganese (Mn<sup>2+</sup>) on proliferation, Mn<sup>2+</sup> acquisition, anti-oxidative system, and biofilm formation of <italic>P. putida</italic> MnB1. The related orthologs of 4 genes, <italic>mco</italic>, <italic>mnt</italic>ABC, <italic>sod</italic>, and <italic>bifA</italic>, were amplified from <italic>P. putida</italic> GB1 and their involvement were assayed, respectively. We found that <italic>P. putida</italic> MnB1 degraded H<sub>2</sub>O<sub>2</sub>, and quickly recovered for proliferation, but its intracellular oxidative stress state was maintained, with rapid biofilm formation after H<sub>2</sub>O<sub>2</sub> depletion. The data from <italic>mco</italic>, <italic>mnt</italic>ABC, <italic>sod</italic> and <italic>bifA</italic> expression levels by qRT-PCR, elucidated a sensitivity toward <italic>bifA</italic>-mediated biofilm formation, in contrary to intracellular anti-oxidative system under H<sub>2</sub>O<sub>2</sub> exposure. Meanwhile, Mn<sup>2+</sup> ion supply inhibited biofilm formation of <italic>P. putida</italic> MnB1. The expression pattern of these genes showed that Mn<sup>2+</sup> ion supply likely functioned to modulate biofilm formation rather than only acting as nutrient substrate for <italic>P. putida</italic> MnB1. Furthermore, blockade of BifA activity by GTP increased the formation and development of biofilms during H<sub>2</sub>O<sub>2</sub> exposure, while converse response to Mn<sup>2+</sup> ion supply was evident. These distinct cellular responses to H<sub>2</sub>O<sub>2</sub> and Mn<sup>2+</sup> provide insights on the common mechanism by which environmental microorganisms may be protected from exogenous factors. We postulate that BifA-mediated biofilm formation but not intracellular anti-oxidative system may be a primary protective strategy adopted by <italic>P. putida</italic> MnB1. These findings will highlight the understanding of microbial adaptation mechanisms to distinct environmental stresses.</p>