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.

Two bacterial strains, designated JAM1(T) and JAM7(T), 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 JAM1(T) 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 JAM1(T) and JAM7(T) 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 JAM1(T). No such operons were found in strain JAM7(T). 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 JAM1(T) (=DSM 25689(T)=ATCC BAA-2433(T)) and Methylophaga frappieri sp. nov. for type strain JAM7(T) (=DSM 25690(T)=ATCC BAA-2434(T)) are proposed.

Hyphomicrobium nitrativorans sp. nov., isolated from the biofilm of a methanol-fed denitrification system treating seawater at the Montreal Biodome.

A budding prosthecate bacterial strain, designated NL23(T), was isolated from a methanol-fed denitrification system treating seawater at the Montreal Biodome, Canada. Phylogenetic analysis based on 16S rRNA (rRNA) gene sequences showed that the strain was affiliated with the genus Hyphomicrobium of the Alphaproteobacteria and was most closely related to Hyphomicrobium zavarzinii with 99.4 % sequence similarity. Despite this high level of 16S rRNA gene sequence similarity, DNA-DNA hybridization assays showed that strain NL23(T) was only distantly related to H. zavarzinii ZV-622(T) (12 %). Strain NL23(T) grew aerobically, but also had the capacity to grow under denitrifying conditions in the presence of nitrate without nitrite accumulation. Growth occurred at pH 7.0-9.5, with 0-1 % NaCl and at temperatures of 15-35 °C. Major fatty acids were C18 : 1ω7c or ω6c (84.6 %) and C18 : 0 (8.5 %), and major quinones were Q8 (5 %) and Q9 (95 %). The complete genome of the strain was sequenced and showed a DNA G+C content of 63.8 mol%. Genome analysis predicted open reading frames (ORF) encoding the key enzymes of the serine pathway as well as enzymes involved in methylotrophy. Also, ORF encoding a periplasmic nitrate reductase (Nap), a nitrite reductase (Nir), a nitric oxide reductase (Nor) and a nitrous oxide reductase (Nos) were identified. Our results support that strain NL23(T) represents a novel species within the genus Hyphomicrobium, for which the name Hyphomicrobium nitrativorans sp. nov. is proposed. The type strain is NL23(T) ( = ATCC BAA-2476(T) = LMG 27277(T)).

Complete genome sequences of Methylophaga sp. strain JAM1 and Methylophaga sp. strain JAM7.

Methylophaga sp. strains JAM1 and JAM7 have been isolated from a denitrification system. Strain JAM1 was the first Methylophaga strain reported to be able to grow under denitrifying conditions. Here, we report the complete genome sequences of the two strains, which allowed prediction of gene clusters involved in denitrification in strain JAM1.

Complete Genome Sequence of Hyphomicrobium nitrativorans Strain NL23, a Denitrifying Bacterium Isolated from Biofilm of a Methanol-Fed Denitrification System Treating Seawater at the Montreal Biodome.

Hyphomicrobium nitrativorans strain NL23 has been isolated from the biofilm of a denitrification system treating seawater. This strain has the capacity to denitrify using methanol as a carbon source. Here, we report the complete genome sequence of this strain in an effort to increase understanding of the function of this bacterium within the biofilm.