Open AccessHidden in plain sight: discovery of sheath‐forming, iron‐oxidizing Zetaproteobacteria at Loihi Seamount, Hawaii, USA
Author(s) -
Fleming Emily J.,
Davis Richard E.,
McAllister Sean M.,
Chan Clara S.,
Moyer Craig L.,
Tebo Bradley M.,
Emerson David
Publication year - 2013
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/1574-6941.12104
Subject(s) - biology , seamount , hydrothermal vent , microbial mat , terminal restriction fragment length polymorphism , botany , cyanobacteria , hydrothermal circulation , paleontology , restriction fragment length polymorphism , bacteria , polymerase chain reaction , biochemistry , gene
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, L eptothrix ochracea . 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 L . ochracea . Clone libraries of the SSU rRNA gene from this top layer were dominated by Zetaproteobacteria , and lacked phylotypes related to L . ochracea . In mats with similar morphologies, terminal‐restriction fragment length polymorphism (T‐RFLP) data along with quantitative PCR (Q‐PCR) analyses using a Zetaproteobacteria ‐specific primer confirmed the presence and abundance of Zetaproteobacteria . A Zetaproteobacteria fluorescence in situ hybridization (FISH) probe hybridized to ensheathed cells (4% of total cells), while a L . ochracea ‐specific probe and a Betaproteobacteria probe did not. Together, these results constitute the discovery of a novel group of marine sheath‐forming FeOB bearing a striking morphological similarity to L . ochracea , but belonging to an entirely different class of Proteobacteria .