Both sulfate-reducing bacteria and Enterobacteriaceae take part in marine biocorrosion of carbon steel.
OBJECTIVE
In order to evaluate the part played in biocorrosion by microbial groups other than sulfate-reducing bacteria (SRB), we characterized the phylogenetic diversity of a corrosive marine biofilm attached to a harbour pile structure as well as to carbon steel surfaces (coupons) immersed in seawater for increasing time periods (1 and 8 months). We thus experimentally checked corroding abilities of defined species mixtures.


RESULTS
Microbial community analysis was performed using both traditional cultivation techniques and polymerase chain reaction cloning-sequencing of 16S rRNA genes. Community structure of biofilms developing with time on immersed coupons tended to reach after 8 months, a steady state similar to the one observed on a harbour pile structure. Phylogenetic affiliations of isolates and cloned 16S rRNA genes (rrs) indicated that native biofilms (developing after 1-month immersion) were mainly colonized by gamma-proteobacteria. Among these, Vibrio species were detected in majority with molecular methods while cultivation techniques revealed dominance of Enterobacteriaceae such as Citrobacter, Klebsiella and Proteus species. Conversely, in mature biofilms (8-month immersion and pile structure), SRB, and to a lesser extent, spirochaetes were dominant.


CONCLUSIONS
Corroding activity detection assays confirmed that Enterobacteriaceae (members of the gamma-proteobacteria) were involved in biocorrosion of metallic material in marine conditions.


CONCLUSIONS
In marine biofilms, metal corrosion may be initiated by Enterobacteriaceae.
Bermont-Bouis
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D
Corrodys, Centre de Corrosion marine et Biologique, Equeurdreville, France.
Janvier
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M
Grimont
P A D
PA
Dupont
I
I
Vallaeys
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T
D001483:Base Sequence; D044822:Biodiversity; D018441:Biofilms; D002244:Carbon; D003001:Cloning, Molecular / Q000379:methods; D003343:Corrosion; D004755:Enterobacteriaceae / Q000235:genetics / Q000502:physiology*; D007101:Immersion; D008855:Microscopy, Electron, Scanning / Q000379:methods; D010802:Phylogeny; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology; D013232:Steel; D014871:Water Microbiology
D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D013232:Steel; D002244:Carbon