Hidden in plain sight: discovery of sheath‐forming, iron‐oxidizing Zetaproteobacteria at Loihi Seamount, Hawaii, USA. Issue 1 (15th April 2013)

• Record Type: Journal Article
• Authors: Fleming, Emily J.; Davis, Richard E.; McAllister, Sean M.; Chan, Clara S.; Moyer, Craig L.; Tebo, Bradley M.; Emerson, David
• Is Part Of: FEMS microbiology ecology. Volume 85:Issue 1(2013)
• Page Start: 116
• Page End: 127
• Publication Date: 2013-04-15
• Subjects: Microbial ecology -- Periodicals; Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1574-6941.12104
• Languages: English
• ISSNs: 0168-6496

Abstract

<abstract abstract-type="main" id="fem12104-abs-0001"> <title>Abstract</title> <p>Lithotrophic iron‐oxidizing bacteria (FeOB) form microbial mats at focused flow or diffuse flow vents in deep‐sea hydrothermal systems where Fe(II) is a dominant electron donor. These mats composed of biogenically formed Fe(III)‐oxyhydroxides include twisted stalks and tubular sheaths, with sheaths typically composing a minor component of bulk mats. The micron diameter Fe(III)‐oxyhydroxide‐containing tubular sheaths bear a strong resemblance to sheaths formed by the freshwater FeOB, <italic>Leptothrix ochracea</italic>. We discovered that veil‐like surface layers present in iron‐mats at the Loihi Seamount were dominated by sheaths (40–60% of total morphotypes present) compared with deeper (> 1 cm) mat samples (0–16% sheath). By light microscopy, these sheaths appeared nearly identical to those of <italic>L. ochracea</italic>. Clone libraries of the SSU rRNA gene from this top layer were dominated by <italic>Zetaproteobacteria</italic>, and lacked phylotypes related to <italic>L</italic>. <italic>ochracea</italic>. In mats with similar morphologies, terminal‐restriction fragment length polymorphism (T‐RFLP) data along with quantitative PCR (Q‐PCR) analyses using a <italic>Zetaproteobacteria</italic>‐specific primer confirmed the presence and abundance of <italic>Zetaproteobacteria</italic>. A <italic>Zetaproteobacteria</italic> fluorescence <italic>in situ</italic> hybridization (FISH) probe hybridized to ensheathed cells (4% of total cells), while a <italic>L</italic>. <italic>ochracea</italic>‐specific probe and a <italic>Betaproteobacteria</italic> probe did not. Together, these results constitute the discovery of a novel group of marine sheath‐forming FeOB bearing a striking morphological similarity to <italic>L</italic>. <italic>ochracea</italic>, but belonging to an entirely different class of <italic>Proteobacteria</italic>.</p> </abstract>