Two Bacteria Phylotypes Are Predominant in the Suiyo Seamount Hydrothermal Plume

Abstract

Microbial diversity and populations in a hydrothermal plume that was present inside the caldera of the Suiyo Seamount, a submarine volcano on the Izu-Bonin Arc, were investigated by performing a phylogenetic analysis of the 16S rRNA gene and by using fluorescence in situ hybridization (FISH). Corresponding to transmissivity, an indicator of turbidity, the vertical total cell count as determined by 4,6-diamidino-2-phenylindole (DAPI) staining varied from 5.6 ؋ 10 4 to 1.1 ؋ 10 5 cells ml ؊1 , and the apparent plume layer was assessed to be at a depth of 1,050 to 1,200 m inside the caldera and to contain 1.0 ؋ 10 5 to 1.1 ؋ 10 5 cells ml ؊1 . From microbial samples collected in the plume by an in situ filtration system, the following two major phylogenetic groups, which were closely related to sulfur-oxidizing microbes, were obtained: the SUP05 group belonging to the gamma subclass of the Proteobacteria (13 of 20 clones) and the SUP01 group belonging to the epsilon subclass of the Proteobacteria (5 of 20 clones). Specific oligonucleotide probes for these groups (SUP05-187 and SUP01-63) were designed and were used with various water samples obtained from the Suiyo Seamount. In the apparent plume layer, up to 66% of the total counts of microbial cells were estimated to be Bacteria cells that hybridized to EUB338, and few cells were identified by the archaeal probe ARCH915. Almost all Bacteria cells were hard to identify with the known group-specific probes, such as ALF19, GAM42a, and CF319, while 88 to 90% of the Bacteria cells hybridized with SUP05-187 and >98% of them were considered members of the SUP05 and SUP01 populations. In a low-temperature vent fluid emitted from a bivalvecolonized mound, the SUP05 cells accounted for >99% of the Bacteria cells, suggesting that a portion of the plume cells originated on the surface of the seafloor at a depth of about 1,380 m. From further analysis of cell morphology (i.e., cell size and cell elongation index) we inferred that the SUP05 cells were active in the plume layer at a depth of 1,050 to 1,200 m compared to the activity in a near-bottom layer, while many elongated cells were found between these layers. These findings suggest that the morphology and distribution of SUP05 cells have complex relationships with hydrothermal activities and water circulation. Although growth and production rates remain to be defined, we concluded that this Suiyo Seamount caldera has functioned as a natural continuous incubator for these two phylotypes of Bacteria in an aphotic deep-sea environment.

In Situ Determination of Bacterial Growth in Mixing Zone of Hydrothermal Vent Field on the Hatoma Knoll, Southern Okinawa Trough

“…The Epsilonproteobacteria have been known as common member discovered from benthic mixing zone of hydrothermal system (Campbell et al 2006), and a majority of epibiotic microbial community on Sinkaia crosnieri Watsuji et al 2010). The free-living Gammaproteobacteria, SUP05 potential sulfur oxidizing phylotype, dwelled in hydrothermal system have been discovered as common member in chemoautotrophic group of hydrothermal plume (Dick et al 2013;Sunamura et al 2004). The different ecophysiological functions between Epsilonproteobacteria and Gammaproteobacteria probably induced the habitat segregation within hydrothermal system (Nakagawa and Takai 2008;Yamamoto and Takai 2011).…”

The metatranscriptome of a deep-sea hydrothermal plume is dominated by water column methanotrophs and lithotrophs

“…Thus, little is known about the nature of plume microbial communities or their relationship to those of the seafloor or surrounding deep seawater. Several studies have reported the SUP05 group of sulfur-oxidizing Gammaproteobacteria in deep-sea hydrothermal plumes in widespread geographical locations (Sunamura et al, 2004;Dick and Tebo, 2010;German et al, 2010). Other prevalent microbial groups identified in plumes include Epsilonproteobacteria (Sunamura et al, 2004;Nakagawa et al, 2005;German et al, 2010), ammonia-oxidizing Betaproteobacteria (Lam et al, 2008), methanotrophs (Naganuma et al, 2004;Lam et al, 2008) and Marine Group I (MGI) archaea (Takai et al, 2004).…”

Quantification of Microbial Communities in Hydrothermal Vent Habitats of the Southern Mariana Trough and the Mid-Okinawa Trough

“…In the samples from the MOT, most oligonucleotide probes identified very few cells, with the exception of SUP05-187. The SUP05 group of sulfur oxidizers in Gammaproteobacteria was most abundant near vent fauna habitats in the MOT, as previously shown in the hydrothermal plume at the Suiyo Seamount (Sunamura et al 2004). Sulfur oxidation would be one of the most feasible reactions in the hydrothermal environment of the MOT.…”