Presence of glucose, xylose, and glycerol fermenting bacteria in the deep biosphere of the former Homestake gold mine, South Dakota

Abstract

Eight fermentative bacterial strains were isolated from mixed enrichment cultures of a composite soil sample collected at 1.34 km depth from the former Homestake gold mine in Lead, SD, USA. Phylogenetic analysis of their 16S rRNA gene sequences revealed that these isolates were affiliated with the phylum Firmicutes belonging to genera Bacillus and Clostridium. Batch fermentation studies demonstrated that isolates had the ability to ferment glucose, xylose, or glycerol to industrially valuable products such as ethanol and 1,3-propanediol (PDO). Ethanol was detected as the major fermentation end product in glucose-fermenting cultures at pH 10 with yields of 0.205–0.304 g of ethanol/g of glucose. While a xylose-fermenting strain yielded 0.189 g of ethanol/g of xylose and 0.585 g of acetic acid/g of xylose at the end of fermentation. At pH 7, glycerol-fermenting isolates produced PDO (0.323–0.458 g of PDO/g of glycerol) and ethanol (0.284–0.350 g of ethanol/g of glycerol) as major end products while acetic acid and succinic acid were identified as minor by-products in fermentation broths. These results suggest that the deep biosphere of the former Homestake gold mine harbors bacterial strains which could be used in bio-based production of ethanol and PDO.

Establishment of the Deep Mine Microbial Observatory (DeMMO), South Dakota, USA, a Geochemically Stable Portal Into the Deep Subsurface

“…Previous geochemical and geomicrobiological work at SURF has focused on the ore formation and emplacement (Caddey, 1991;Morelli et al, 2010;Steadman and Large, 2016), hydrology (Murdoch et al, 2011;Kennedy et al, 2015), and geomicrobiology of mine biofilms and soils largely in the context of bioprospecting (Rastogi et al, 2009(Rastogi et al, , 2010(Rastogi et al, , 2013Waddell et al, 2010). In 2013 the NASA Astrobiology Institute Team Life Underground began work at SURF, characterizing geochemistry, microbiology, and redox reaction energetics at key sites with an eye toward habitability (Osburn et al, 2014).…”

The Sanford Underground Research Facility at Homestake

“…Biodiversity (BHSU) Microbiology Surface, 300L, [45,46,47] 2000L, 4100L, 4550L, 4850L Biofuels (SDSMT) Biofuels 4550L, 4850L, [48,49,50,51], 5000L [52,53,54,55] Lignocellulose (SDSU) Biofuels 1700L, 4850L [56,57] Syngas (SDSMT) Biofuels 4850L [58,59,60] Life UndergroundWater in drill holes, Surface, 800L, [61] NASA Astrobiology Institute geomicrobiology 4850L Engineering Xilinx, Inc. Chip error testing 4850L The LUX collaboration published results in October 2013 from their first underground data run [23] and started a longer run (nominally 300 live days) in October 2014. LUX is expecting to complete their experimental program in 2016.…”

Contrasting Variable and Stable Subsurface Microbial Populations: an ecological time series analysis from the Deep Mine Microbial Observatory, South Dakota, USA

“…Accessible levels extend from 91 m to 1.5 km below surface with flooded levels down to 2.5 km. Previous sequencing efforts at SURF have focused on mine soils (Rastogi et al, 2009;2010) and industrially relevant metabolisms (Rastogi et al, 2013). A detailed comparison between the geochemistry and microbial diversity of planktonic fluids was published in (Osburn et al, 2014), followed by a comparison between fluid and rock communities (Momper, Kiel Reese, et al, 2017), and a metagenomic analysis of two borehole sites (Momper, Jungbluth, Lee, and Amend, 2017a).…”