Methylophaga nitratireducenticrescens sp. nov. and Methylophaga frappieri sp. nov., isolated from the biofilm of the methanol-fed denitrification system treating the seawater at the Montreal Biodome
2013
Villeneuve, Céline | Martineau, Christine | Mauffrey, Florian | Villemur, Richard
Two bacterial strains, designated JAM1T and JAM7T, were isolated from a methanol-fed denitrification system treating seawater at the Montreal Biodome, Canada. They were affiliated within the genus Methylophaga of the Gammaproteobacteria by analysis of the 16S rRNA gene sequences. Strain JAM1T had the capacity to grow under denitrifying conditions by reducing nitrate into nitrite which is unique among the species of the genus Methylophaga. Major fatty acids were C16 : 1ω7c or ω6c, C16 : 0 and C18 : 1ω7c or ω6c. The major ubiquinone was Q8. Both strains required vitamin B12 and Na+ ions for growth. The genomes of strains JAM1T and JAM7T have been completely sequenced and showed a DNA G+C content of 44.7 mol% and 47.8 mol%, respectively. Growth occurred at pH 6–11 and at 0.5–8 % NaCl. Both genomes contained predicted ORFs encoding the key enzymes of the ribulose monophosphate pathway. Also, operons encoding two nitrate reductases (Nar), two nitric oxide reductases (Nor), one nitrous oxide reductase (Nos) and one truncated nitrite reductase (NirK) were clustered in a 67 kb chromosomal region in strain JAM1T. No such operons were found in strain JAM7T. These results supported the affiliation of the two strains as novel species within the genus Methylophaga. The names Methylophaga nitratireducenticrescens sp. nov. for type strain JAM1T ( = DSM 25689T = ATCC BAA-2433T) and Methylophaga frappieri sp. nov. for type strain JAM7T ( = DSM 25690T = ATCC BAA-2434T) are proposed.
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