Variance in Resuscitation and Activity of Thermophilic Endospores in Crustal-Fluid-Impacted Marine Sediments
Faculty Mentor Information
Dr. Anirban Chakraborty, Idaho State University; and Rhys Ellis, Idaho State University
Presentation Date
7-15-2026
Abstract
The oceanic crust represents one of the largest reservoirs of microbial life on Earth. Upon entering the crustal reservoir through seamounts, seawater gradually transforms chemically into hydrothermal crustal fluids that later efflux back into the ocean, also via seamounts. This subseafloor aquifer hosts a microbiome responsible for performing vital geochemical processes, i.e., acting as a sulfate sink. Our project aims to investigate the potential of microbial dispersal aided by fluid expulsion from the crustal biosphere to the overlying ocean using thermophilic bacterial endospores (thermospores) as model organisms. Since thermospores remain dormant at low temperatures, their ubiquitous occurrence on the seabed globally can only be explained by upward dispersal from warm subsurface habitats. We collected triplicate sediment samples from three coring sites within a transect moving away from an active crustal fluid emission site. To investigate the thermospore community, anoxic cultivations were established at two temperatures (50°C and 65°C) for six weeks. Ion chromatography and genomic DNA concentration were used to evaluate and compare the extent of sulfate reduction and biomass production, respectively, between enrichment cultures. We observed increasing DNA concentrations and evidence of an early onset of sulfate depletion in the incubations at 50°C compared to at 65°C. Furthermore, we observed that the coring location closest to the crustal fluid emission site had more pronounced sulfate depletion compared to more distant sites. Based on these observations, we hypothesize that thermospore communities revived in our incubation experiments varied with temperature and distance from the fluid expulsion source.
Variance in Resuscitation and Activity of Thermophilic Endospores in Crustal-Fluid-Impacted Marine Sediments
The oceanic crust represents one of the largest reservoirs of microbial life on Earth. Upon entering the crustal reservoir through seamounts, seawater gradually transforms chemically into hydrothermal crustal fluids that later efflux back into the ocean, also via seamounts. This subseafloor aquifer hosts a microbiome responsible for performing vital geochemical processes, i.e., acting as a sulfate sink. Our project aims to investigate the potential of microbial dispersal aided by fluid expulsion from the crustal biosphere to the overlying ocean using thermophilic bacterial endospores (thermospores) as model organisms. Since thermospores remain dormant at low temperatures, their ubiquitous occurrence on the seabed globally can only be explained by upward dispersal from warm subsurface habitats. We collected triplicate sediment samples from three coring sites within a transect moving away from an active crustal fluid emission site. To investigate the thermospore community, anoxic cultivations were established at two temperatures (50°C and 65°C) for six weeks. Ion chromatography and genomic DNA concentration were used to evaluate and compare the extent of sulfate reduction and biomass production, respectively, between enrichment cultures. We observed increasing DNA concentrations and evidence of an early onset of sulfate depletion in the incubations at 50°C compared to at 65°C. Furthermore, we observed that the coring location closest to the crustal fluid emission site had more pronounced sulfate depletion compared to more distant sites. Based on these observations, we hypothesize that thermospore communities revived in our incubation experiments varied with temperature and distance from the fluid expulsion source.