Investigation of Siderophore-Promoted and Reductive Dissolution of Dust in Marine Microenvironments Such as Trichodesmium Colonies

Abstract

Bio-Enhanced Dust Dissolution Fe-quotas and growth rates we calculated the Fe requirements of the colonies under Felimited and Fe-replete conditions. The calculated dissolved Fe supply from dust retained within colonies can fulfill the Fe requirements of slow growing Fe-limited colonies, but cannot support fast growth and/or higher cellular Fe quotas. We conclude that despite these bio-dissolution mechanisms, dust-Fe availability to Trichodesmium is low and propose that it employs additional mechanisms to actively mine Fe from dust.

The Influence of Glacial Cover on Riverine Silicon and Iron Exports in Chilean Patagonia

“…Recent research has also shown that some diatoms species can effectively “mine” and enhance dissolution of other particulate Fe phases that might not be quantified with the FeA extraction (Kessler et al, 2020; Rubin et al, 2011; Shoenfelt et al, 2017). For example, additions of Fe(II)‐rich glaciogenic dust from Patagonia have been shown to significantly enhance diatom growth in sFe‐limited culture experiments, compared to additions of Fe(III)‐rich non‐glaciogenic dust (Shoenfelt et al, 2017).…”

Mechanisms and heterogeneity of in situ mineral processing by the marine nitrogen fixer Trichodesmium revealed by single-colony metaproteomics

“…This is important because Trichodesmium thrives in regions where iron-rich continental dust is deposited such as the North Atlantic, Red Sea, and near landforms including Australia and the Caribbean islands [ 18 , 19 ]. Dust addition experiments, both in the laboratory and in shipboard incubations, have demonstrated that Trichodesmium puff colonies can selectively capture [ 20 ] and efficiently acquire iron from (oxy/hydro)oxide dust minerals [ 14 – 16 , 21 ] with the involvement of the epibiont community [ 22 , 23 ]. Dust particles can relieve iron stress and improve Trichodesmium’s metabolic function [ 24 , 25 ], but may also act as ballast leading to accelerated sinking of Trichodesmium colonies and enhanced carbon sequestration [ 26 ].…”

Colonies of the marine cyanobacterium Trichodesmium optimize dust utilization by selective collection and retention of nutrient-rich particles

“…This is in contrast to the $80-fold higher cellular requirements for P compared with Fe (San ˜udo- Wilhelmy et al, 2001Wilhelmy et al, , 2004. Despite the low overall solubility of both Fe and P from dust, typically estimated 0.1%-10% (Aguilar-Islas et al, 2010;Mahowald et al, 2005Mahowald et al, , 2008Stockdale et al, 2016), Trichodesmium can employ a variety of biochemical pathways and physical mechanisms in order to enhance the solubility and bioavailability of Fe from dust (Basu et al, 2019;Basu and Shaked, 2018;Eichner et al, 2019Eichner et al, , 2020Held et al, 2020a;Kessler et al, 2020b;Rubin et al, 2011). The effect of such mechanisms on dust-P solubility has not yet been studied, but as P is often associated with Fe, it is likely that Trichodesmium can also modify dust-P and enhance its bioavailability.…”

“…The ability to remove particles provides flexibility with regards to the amount and type of particles colonies can retain. Such flexibility enables colonies to offset the potential negative effects of a high particle load such as buoyancy loss, exposure to toxic trace elements present in dust, increased visibility to predators, self-shading by particles, and restricted diffusion of solutes (Held et al, 2020a;Kessler et al, 2020b;Paytan et al, 2009;Walsby, 1992). An ability to remove particles also enables colonies to rapidly change their pool of particles and replace nutrient-exhausted particles with fresh ones, potentially providing larger nutrient fluxes.…”

“…The colonies' clear preference for dust in comparison with all other minerals (Figures 7 and 9) may involve both physical and chemical characteristics of dust. Natural dust and aerosols contain differently sized single and aggregated particles, varying in shape and surface roughness (Genga et al, 2018;Kessler et al, 2020b;Marcotte et al, 2020), potentially making it easier to translocate and center in comparison with some of the homogeneous smooth minerals that were used. In addition, dust may contain nutrients other than P or Fe, such as additional trace metals, organic matter, and bacteria (Chen et al, 2007;Herut et al, 2016;Torfstein et al, 2017).…”