{"id":{"repo_id":"umn","oai_identifier":"oai:conservancy.umn.edu:11299/183282"},"canonical_url":"https://search.dev.ndltd.org/etd/umn/oai:conservancy.umn.edu:11299/183282","repository":{"repo_id":"umn","name":"University of Minnesota","base_url":"https://conservancy.umn.edu/server/oai/request"},"display":{"title":"Microbial Communities Associated with Phosphoclast-bearing Sediments of the Benguela Upwelling Zone","abstract":"Phosphorus is a limiting nutrient in the environment and is an important component of many biological molecules. Calcium phosphate mineral deposits, known as phosphorites, are also the primary source of P for agriculture. Understanding phosphorite formation may improve management of P resources. However, the processes that mediate calcium phosphate mineral precipitation in certain marine pore waters remain poorly understood. Phosphogenesis occurs in sediments beneath some oceanic upwelling zones that harbor polyphosphate-accumulating giant sulfur bacteria (GSB). These bacteria may concentrate phosphate in sediment pore waters, creating supersaturated conditions with respect to apatite. However, the relationship between microbes and phosphogenesis is not fully resolved. To further study this relationship, we examined microbial communities from two sources: sediment cores recovered from the shelf of the Benguela region, and DNA extracted from washed phosphoclasts recovered from those same sediments. We used iTag and clone library sequencing of the 16S rRNA gene to examine the microbial communities and their relationship with the environment. We found that many of our sediments shared large numbers of phylotypes with one another, and that the same metabolic guilds were represented at localities across the shelf. Sulfur-reducing bacteria and sulfur-oxidizing bacteria were abundant in our datasets. Phylotypes that are known to carry out nitrification and/or anammox (anaerobic ammonia oxidation) were also well-represented. Our phosphoclast extraction, however, contained a distinct microbial community from those observed in the modern sediments. We observed both an enrichment of certain common microbial classes and a complete absence of others. These results could represent an ancient microbial assemblage that was present when the apatite precipitated. While these taxa may or may not have contributed to apatite precipitation, several groups represented in the phosphoclast dataset have the genetic potential, as determined through the analysis of published genomes, to synthesize, and perhaps accumulate, polyphosphate.","abstract_html":"Phosphorus is a limiting nutrient in the environment and is an important component of many biological molecules. Calcium phosphate mineral deposits, known as phosphorites, are also the primary source of P for agriculture. Understanding phosphorite formation may improve management of P resources. However, the processes that mediate calcium phosphate mineral precipitation in certain marine pore waters remain poorly understood. Phosphogenesis occurs in sediments beneath some oceanic upwelling zones that harbor polyphosphate-accumulating giant sulfur bacteria (GSB). These bacteria may concentrate phosphate in sediment pore waters, creating supersaturated conditions with respect to apatite. However, the relationship between microbes and phosphogenesis is not fully resolved. To further study this relationship, we examined microbial communities from two sources: sediment cores recovered from the shelf of the Benguela region, and DNA extracted from washed phosphoclasts recovered from those same sediments. We used iTag and clone library sequencing of the 16S rRNA gene to examine the microbial communities and their relationship with the environment. We found that many of our sediments shared large numbers of phylotypes with one another, and that the same metabolic guilds were represented at localities across the shelf. Sulfur-reducing bacteria and sulfur-oxidizing bacteria were abundant in our datasets. Phylotypes that are known to carry out nitrification and/or anammox (anaerobic ammonia oxidation) were also well-represented. Our phosphoclast extraction, however, contained a distinct microbial community from those observed in the modern sediments. We observed both an enrichment of certain common microbial classes and a complete absence of others. These results could represent an ancient microbial assemblage that was present when the apatite precipitated. While these taxa may or may not have contributed to apatite precipitation, several groups represented in the phosphoclast dataset have the genetic potential, as determined through the analysis of published genomes, to synthesize, and perhaps accumulate, polyphosphate.","abstract_has_math":false,"creators":["Zoss, Roman"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-09","date_published":"2016-09","updated_at":"2026-07-24T05:19:54Z","subjects":["Ancient DNA","Benguela","Namibia","Phosphorite","Thiomargarita"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11299/183282","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Zoss, Roman"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2016-12-19T21:09:23Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2016-12-19T21:09:23Z"]},{"key":"dc:date.issued","label":"Date","values":["2016-09"]},{"key":"dc:type","label":"Dc Type","values":["Thesis or Dissertation"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Ancient DNA","Benguela","Namibia","Phosphorite","Thiomargarita"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11299/183282"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["University of Minnesota M.S. thesis. September 2016. Major: Earth Sciences. Advisor: Jake Bailey. 1 computer file (PDF); vi, 51 pages."]},{"key":"dc:description.abstract","label":"Abstract","values":["Phosphorus is a limiting nutrient in the environment and is an important component of many biological molecules. Calcium phosphate mineral deposits, known as phosphorites, are also the primary source of P for agriculture. Understanding phosphorite formation may improve management of P resources. However, the processes that mediate calcium phosphate mineral precipitation in certain marine pore waters remain poorly understood. Phosphogenesis occurs in sediments beneath some oceanic upwelling zones that harbor polyphosphate-accumulating giant sulfur bacteria (GSB). These bacteria may concentrate phosphate in sediment pore waters, creating supersaturated conditions with respect to apatite. However, the relationship between microbes and phosphogenesis is not fully resolved. To further study this relationship, we examined microbial communities from two sources: sediment cores recovered from the shelf of the Benguela region, and DNA extracted from washed phosphoclasts recovered from those same sediments. We used iTag and clone library sequencing of the 16S rRNA gene to examine the microbial communities and their relationship with the environment. We found that many of our sediments shared large numbers of phylotypes with one another, and that the same metabolic guilds were represented at localities across the shelf. Sulfur-reducing bacteria and sulfur-oxidizing bacteria were abundant in our datasets. Phylotypes that are known to carry out nitrification and/or anammox (anaerobic ammonia oxidation) were also well-represented. Our phosphoclast extraction, however, contained a distinct microbial community from those observed in the modern sediments. We observed both an enrichment of certain common microbial classes and a complete absence of others. These results could represent an ancient microbial assemblage that was present when the apatite precipitated. While these taxa may or may not have contributed to apatite precipitation, several groups represented in the phosphoclast dataset have the genetic potential, as determined through the analysis of published genomes, to synthesize, and perhaps accumulate, polyphosphate."]},{"key":"dc:title","label":"Title","values":["Microbial Communities Associated with Phosphoclast-bearing Sediments of the Benguela Upwelling Zone"]}]}],"canonical_facts":{"dc:creator":["Zoss, Roman"],"dc:date.accessioned":["2016-12-19T21:09:23Z"],"dc:date.available":["2016-12-19T21:09:23Z"],"dc:date.issued":["2016-09"],"dc:description":["University of Minnesota M.S. thesis. September 2016. Major: Earth Sciences. Advisor: Jake Bailey. 1 computer file (PDF); vi, 51 pages."],"dc:description.abstract":["Phosphorus is a limiting nutrient in the environment and is an important component of many biological molecules. Calcium phosphate mineral deposits, known as phosphorites, are also the primary source of P for agriculture. Understanding phosphorite formation may improve management of P resources. However, the processes that mediate calcium phosphate mineral precipitation in certain marine pore waters remain poorly understood. Phosphogenesis occurs in sediments beneath some oceanic upwelling zones that harbor polyphosphate-accumulating giant sulfur bacteria (GSB). These bacteria may concentrate phosphate in sediment pore waters, creating supersaturated conditions with respect to apatite. However, the relationship between microbes and phosphogenesis is not fully resolved. To further study this relationship, we examined microbial communities from two sources: sediment cores recovered from the shelf of the Benguela region, and DNA extracted from washed phosphoclasts recovered from those same sediments. We used iTag and clone library sequencing of the 16S rRNA gene to examine the microbial communities and their relationship with the environment. We found that many of our sediments shared large numbers of phylotypes with one another, and that the same metabolic guilds were represented at localities across the shelf. Sulfur-reducing bacteria and sulfur-oxidizing bacteria were abundant in our datasets. Phylotypes that are known to carry out nitrification and/or anammox (anaerobic ammonia oxidation) were also well-represented. Our phosphoclast extraction, however, contained a distinct microbial community from those observed in the modern sediments. We observed both an enrichment of certain common microbial classes and a complete absence of others. These results could represent an ancient microbial assemblage that was present when the apatite precipitated. While these taxa may or may not have contributed to apatite precipitation, several groups represented in the phosphoclast dataset have the genetic potential, as determined through the analysis of published genomes, to synthesize, and perhaps accumulate, polyphosphate."],"dc:identifier.uri":["http://hdl.handle.net/11299/183282"],"dc:language.iso":["en"],"dc:subject":["Ancient DNA","Benguela","Namibia","Phosphorite","Thiomargarita"],"dc:title":["Microbial Communities Associated with Phosphoclast-bearing Sediments of the Benguela Upwelling Zone"],"dc:type":["Thesis or Dissertation"]},"updated_at":"2026-07-24T05:19:54Z"}