Geomicrobiological Properties of Ultra-Deep Granitic Groundwater from the Mizunami Underground Research Laboratory (MIU), Central Japan

Abstract

Although deep subterranean crystalline rocks are known to harbor microbial ecosystems, geochemical factors that constrain the biomass, diversity, and metabolic activities of microorganisms remain to be clearly defined. To better understand the geochemical and microbiological relationships, we characterized granitic groundwater collected from a 1,148- to 1,169-m-deep borehole interval at the Mizunami Underground Research Laboratory site, Japan, in 2005 and 2008. Geochemical analyses of the groundwater samples indicated that major electron acceptors, such as NO(3)(-) and SO(4)(2-), were not abundant, while dissolved organic carbon (not including organic acids), CH(4) and H(2), was moderately rich in the groundwater sample collected in 2008. The total number of acridine orange-stained cells in groundwater samples collected in 2005 and 2008 were 1.1 x 10(4) and 5.2 x 10(4) cells/mL, respectively. In 2005 and 2008, the most common phylotypes determined by 16S rRNA gene sequence analysis were both related to Thauera spp., the cultivated members of which can utilize minor electron donors, such as aromatic and aliphatic hydrocarbons. After a 3-5-week incubation period with potential electron donors (organic acids or CH(4) + H(2)) and with/without electron acceptors (O(2) or NO(3)(-)), dominant microbial populations shifted to Brevundimonas spp. These geomicrobiological results suggest that deep granitic groundwater has been stably colonized by Thauera spp. probably owing to the limitation of O(2), NO(3)(-), and organic acids.

Physiological and genomic features of highly alkaliphilic hydrogen-utilizing Betaproteobacteria from a continental serpentinizing site

“…1, Table 1, Supplementary Table 1). Microbes associated with strains A1, B1 or H1 were also detected in two slightly alkaline deep groundwaters where serpentinization is not suggested (Supplementary Table 1): an ultra-deep granite groundwater in Mizunami27, Japan and borehole water from the 2.0 Ga Bushveld complex at the Evander mine in the Kalahari Shield, South Africa28 (Fig. 1, Table 1).…”

Eukaryotic opportunists dominate the deep-subsurface biosphere in South Africa

“…The 16S rRNA gene clone libraries was comprised of alpha-, beta-, gamma- and delta-proteobacteria, Chlorobi , sulphate-reducing Firmicutes all of which have been previously identified in fracture waters from the crust and in hot continental springs 1 7 8 9 10 11 12 . Random colony selection retrieved 219 full-length 16S rRNA sequences from the Kopanang inline filter.…”

Dissecting the deep biosphere: retrieving authentic microbial communities from packer-isolated deep crystalline bedrock fracture zones

“…Microbial communities inhabiting these environments can vary greatly depending on the geography, geology, and the origin and residence time of fracture water. Rock–water interactions in deep subterranean crystalline bedrock fracture environments provide the fuel for the subsurface ecosystems (Stevens and McKinley, ), and host microbial communities with cell numbers ranging from 10 3 to 10 7 cells mL −1 (Pedersen et al ., ; Pedersen, ; Haveman & Pedersen, ; Lin et al ., ; Sahl et al ., ; Fukuda et al ., ; Itävaara et al ., , b; Nyyssönen et al ., ). Most of the studies characterizing the microbial communities of these environments have been conducted on borehole or free‐flowing fluids from mines or caves (e.g.…”

“…Most of the studies characterizing the microbial communities of these environments have been conducted on borehole or freeflowing fluids from mines or caves (e.g. Northup & Lavoie, 2001;Moser et al, 2003;Lin et al, 2006;Barton & Northup, 2007;Sahl et al, 2008;Davidson et al, 2011) or from drill holes drilled from the surface (Onstott et al, 1998;Shimizu et al, 2006;Fukuda et al, 2010). These studies have relied on several different methods for acquiring the samples.…”