Barium bioaccumulation by bacterial biofilms and implications for Ba cycling and use of Ba proxies
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AuthorMartínez-Ruiz, Francisca; Jroundi, Fadwa; Paytan, A.; Guerra-Tschuschke, Isabel; Abad Grau, María Del Mar; González-Muñoz, María Teresa
Martínez-Ruiz, Francisca; et. al. Barium bioaccumulation by bacterial biofilms and implications for Ba cycling and use of Ba proxies. Nature Communications (2018) 9:1619 [http://hdl.handle.net/10481/53228]
SponsorshipThis study was supported by the European Regional Development Fund (ERDF) cofinanced grant CGL2015-66830-R (MINECO Secretaría de Estado de Investigación, Desarrollo e Innovación, Spain), Research Groups BIO 103 and RNM-179 (Junta de Andalucía), and the University of Granada (Unidad Científica de Excelencia UCEPP2016-05).
Ba proxies have been broadly used to reconstruct past oceanic export production. However, the precise mechanisms underlying barite precipitation in undersaturated seawater are not known. The link between bacterial production and particulate Ba in the ocean suggests that bacteria may play a role. Here we show that under experimental conditions marine bacterial biofilms, particularly extracellular polymeric substances (EPS), are capable of bioaccumulating Ba, providing adequate conditions for barite precipitation. An amorphous P-rich phase is formed at the initial stages of Ba bioaccumulation, which evolves into barite crystals. This supports that in high productivity regions where large amounts of organic matter are subjected to bacterial degradation, the abundant EPS would serve to bind the necessary Ba and form nucleation sites leading to barite precipitation. This also provides new insights into barite precipitation and opens an exciting field to explore the role of EPS in mineral precipitation in the ocean.