Distribution of Thermophilic Bacterial Endospores Across Depth-Stratified Sediment Cores from the North Atlantic Ocean
Faculty Mentor Information
Dr. Anirban Chakraborty, Idaho State University; and Eric Christen, Idaho State University
Presentation Date
7-15-2026
Abstract
Dormant endospore-forming thermophilic bacteria (thermospores) are ubiquitous in the permanently cold seabed globally and are also abundant in the subseafloor sedimentary realm. Using high-temperature incubation experiments, we evaluated the distribution of viable thermospores in 5.5 – 8 meters of sediment column in the Scotian Slope, a continental shelf in the North Atlantic Ocean. Piston cores from two locations at water depth > 2000 m (PC003 and PC015) were collected and split into 20-cm-thick sections from the top and bottom. Sediments from each section were supplemented with artificial seawater medium and incubated at three temperatures (50, 65, and 80°C) to stimulate thermospore germination onboard the research vessel CCGS Hudson. Incubations were subsampled every 3-6 hours up to 48 hours, followed by genomic DNA extraction and 16S rRNA gene amplicon sequencing. Analyzing the composition of the heat-induced sediment community revealed the bottom section of PC003 showed high relative abundance of phylum Bacillota, a bacterial phylum consisting of all known spore-forming lineages, comprising >75% of the community. Conversely, top sections revealed ~25% of the community was comprised of the members of Bacillota. Beta diversity analyses further showed that of top and bottom core sections harbored highly dissimilar thermospore communities. Analyzing relative abundance at lower taxonomic ranks (Family and Genus levels) revealed high proportions of unclassified taxa within both top and bottom core sections. Future work will aim to enhance the taxonomic resolution for improved classification of thermospore taxa using an amplicon sequencing strategy targeting a longer fragment of the 16S rRNA gene.
Distribution of Thermophilic Bacterial Endospores Across Depth-Stratified Sediment Cores from the North Atlantic Ocean
Dormant endospore-forming thermophilic bacteria (thermospores) are ubiquitous in the permanently cold seabed globally and are also abundant in the subseafloor sedimentary realm. Using high-temperature incubation experiments, we evaluated the distribution of viable thermospores in 5.5 – 8 meters of sediment column in the Scotian Slope, a continental shelf in the North Atlantic Ocean. Piston cores from two locations at water depth > 2000 m (PC003 and PC015) were collected and split into 20-cm-thick sections from the top and bottom. Sediments from each section were supplemented with artificial seawater medium and incubated at three temperatures (50, 65, and 80°C) to stimulate thermospore germination onboard the research vessel CCGS Hudson. Incubations were subsampled every 3-6 hours up to 48 hours, followed by genomic DNA extraction and 16S rRNA gene amplicon sequencing. Analyzing the composition of the heat-induced sediment community revealed the bottom section of PC003 showed high relative abundance of phylum Bacillota, a bacterial phylum consisting of all known spore-forming lineages, comprising >75% of the community. Conversely, top sections revealed ~25% of the community was comprised of the members of Bacillota. Beta diversity analyses further showed that of top and bottom core sections harbored highly dissimilar thermospore communities. Analyzing relative abundance at lower taxonomic ranks (Family and Genus levels) revealed high proportions of unclassified taxa within both top and bottom core sections. Future work will aim to enhance the taxonomic resolution for improved classification of thermospore taxa using an amplicon sequencing strategy targeting a longer fragment of the 16S rRNA gene.