Effect and Mechanism of Fe(II) Oxygenation on Activities of Iron and Manganese Cycling Functional Microbes

Geologic microorganisms are the main factors driving the redox cycling of iron and manganese in sedimentary environment. The effect and mechanism of Fe(II) oxygenation on the activities of different iron and manganese cycling functional microbes remain unexplored. In this study,it used Shewanella oneidensis MR-1,Pseudogulbenkiania sp. strain 2002,Pseudomonas putida MnB1,Leptothrix discophora SS-1 as the representative iron and manganese cycling functional microbes,it investigated the difference in effect and mechanisms of Fe(II) oxygenation on the activities of these four bacteria. Results show that the living cell counts of MR-1 and MnB1 decreased by 4-5 lg upon 60 min oxygenation of 0.05 mM Fe(II),but no significant inactivation of SS-1 and S.2002 was observed. The surface absorbed •OH and intracellular •OH produced from Fe(II) oxygenation were the dominant reasons for bacteria inactivation,the extracellular H₂O₂,extracellular dissolved •OH and Fe(III) oxides are minor causes for bacteria inactivation. SS-1 and S.2002 show oxidative stress responses during Fe²⁺ oxygenation,which helped to resist the damage of reactive oxygen species.