Goethite formed in the periplasmic space of pseudomonas sp. JM-7 during Fe cycling enhances its denitrification in water
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
Denitrification-driven Fe(II) oxidation is an important microbial metabolism that connects iron and nitrogen cycling in the environment. The formation of Fe(III) minerals in the periplasmic space has a significant effect on microbial metabolism and electron transfer, but direct evidence of iron ions entering the periplasm and resulting in periplasmic mineral precipitation and electron conduction properties has yet to be conclusively determined. Here, we investigated the pathways and amounts of iron, with different valence states and morphologies, entering the periplasmic space of the denitrifier Pseudomonas sp. JM-7 (P. JM-7), and the possible effects on the electron transfer and the denitrifying ability. When consistently provided with Fe(II) ions (from siderite (FeCO3)), the dissolved Fe(II) ions entered the periplasmic space and were oxidized to Fe(III), leading to the formation of a 25 nm thick crystalline goethite crust, which functioned as a semiconductor, accelerating the transfer of electrons from the intracellular to the extracellular matrix. This consequently doubled the denitrification rate and increased the electron transport capacity by 4-30 times (0.015-0.04 μA). However, as the Fe(II) concentration further increased to above 4 mM, the Fe(II) ions tended to preferentially nucleate, oxidize, and crystallize on the outer surface of P. JM-7, leading to the formation of a densely crystallized goethite layer, which significantly slowed down the metabolism of P. JM-7. In contrast to the Fe(II) conditions, regardless of the initial concentration of Fe(III), it was challenging for Fe(III) ions to form goethite in the periplasmic space. This work has shed light on the likely effects of iron on environmental microorganisms, improved our understanding of globally significant iron and nitrogen geochemical cycles in water, and expanded our ability to study and control these important processes.
Date Issued
2023-08-01
Date Acceptance
2023-07-03
Citation
Environmental Science and Technology (Washington), 2023, 57 (30), pp.11096-11107
ISSN
0013-936X
Publisher
American Chemical Society
Start Page
11096
End Page
11107
Journal / Book Title
Environmental Science and Technology (Washington)
Volume
57
Issue
30
Copyright Statement
Copyright © 2023 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Environ. Sci. Technol. 2023, 57, 30, 11096–11107, after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.est.3c02303
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/37467428
Subjects
denitrifying ability
electron transfer
goethite crust
periplasmic space
Publication Status
Published
Coverage Spatial
United States
Date Publish Online
2023-07-19