Microorganisms in Fe-Mn Nodules and Crusts: Comparative Study between the North and South Atlantic Ocean

• Autor(a) principal: Bergo, Natascha Menezes
• Data de Publicação: 2020
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/21/21134/tde-17052022-110258/
• topic: Atlantic Ocean; Biogeochemical Cycling; Ciclos Biogeoquímicos; Comunidades de Micro-organismos; Crosta de ferromanganes; Deep-sea; Ferromanganese Crust; Ferromanganese Nodule; Mar profundo; Microbial Community; Nódulo de ferromanganes; Oceano Atlântico

Fe-Mn crusts and nodules are deep-sea minerals that are economically and ecologically important. Future mining of these minerals is predicted to have significant effects on biodiversity. Thus, for future mining impact studies, it is crucial to understand the role of crusts and nodules in shaping microbial diversity and function in the deep-sea. The main objective of this thesis was to better understand the bacterial and archaeal diversity associated to Fe-Mn crusts, nodules, coral skeletons, calcarenites and surrounding sediments from two Fe-Mn deposits from Atlantic Ocean. The combination of molecular fingerprinting and geochemical approaches used in this study helped to test how the environmental factors of these habitats affect the structure of microbial communities and investigate general patterns of their distribution in the North and South Atlantic Ocean. We analyzed samples and abiotic data from three oceanographic expeditions: one at Tropic seamount and two at Rio Grande Rise (RGR). In Chapter I, the local and regional scales of microbial community structure and their relation to the environmental factors were investigated at the Tropic seamount and RGR. Also, spatial variations of community structure associated to Fe-Mn deposits from the Atlantic and Pacific Oceans were investigated using 16S rRNA gene sequences from public databases. Our results are in general agreement with previous studies in the Pacific Ocean, confirming that crusts and nodules provide a specific ecological niche. Fe-Mn crusts and nodules from Atlantic seamounts showed a typical deep-sea microbiome, with dominance of the classes Gammaproteobacteria and Alphaproteobacteria, but at higher taxonomic resolution we detected substantial differences. Fe-Mn crusts and nodules from Tropic seamount and RGR host a higher proportion of microbial community composition potentially involved in the metal and nitrogen cycle. Variation in the microbial community structure was linked to local heterogeneity, as depth and environmental variables collected from surrounding deep-sea waters. Differences in Fe- Mn substrates community structure between Tropic seamount and RGR suggest that changes in the environmental setting (i.e. water depth and geochemical compositions) play a significant role in structuring the Fe-Mn crust and nodule microbiome. Microbial community structure and diversity in the Fe-Mn crusts, crust biofilms, coral skeletons and calcarenites from RGR was investigated in Chapter II. Microbial alpha diversity differences were not observed among these Fe-Mn substrates. However, microbial community compositions were found to be different among substrates by water depth and sampling location.