sp. nov., a mercury-methylating bacterium isolated from sediment.

The sulfate-reducing, mercury-methylating strain ND132 was isolated from the brackish anaerobic bottom sediments of Chesapeake Bay, USA. Capable of high levels of mercury (Hg) methylation, ND132 has been widely used as a model strain to study the process and to determine the genetic basis of Hg methylation. Originally called ND132 on the basis of an early partial 16S rRNA sequence, the strain has never been formally described. Phylogenetic and physiological traits place this strain within the genus in the recently reclassified phylum (formerly ). ND132 is most closely related to BerOc1 and J2. Analysis of average nucleotide identity (ANI) of whole-genome sequences showed roughly 88 % ANI between BerOc1 and ND132, and 84 % similarity between ND132 and J2. These cut-off scores <95 %, along with a multi-gene phylogenetic analysis of members of the family and differences in physiology indicate that all three strains represent separate species. The Gram-stain-negative cells are vibrio-shaped, motile and not sporulated. ND132 is a salt-tolerant mesophile with optimal growth in the laboratory at 32 °C, 2 % salinity, and pH 7.8. The DNA G+C content of the genomic DNA is 65.2 %. It is an incomplete oxidizer of short chain fatty acids, using lactate, pyruvate and fumarate with sulfate or sulfite as the terminal electron acceptors. ND132 can respire fumarate using pyruvate as an electron donor. The major fatty acids are iso-C, anteiso-C, iso-C, iso-Cω9 and anteiso-C. We propose the classification of strain ND132 (DSM 110689, ATCC TSD-224) as the type strain sp. nov.