Siderophore-Mediated Iron Dissolution from Nontronites Is Controlled by Mineral Cristallochemistry

Abstract

Bacteria living in oxic environments experience iron deficiency due to limited solubility and slow dissolution kinetics of iron-bearing minerals. To cope with iron deprivation, aerobic bacteria have evolved various strategies, including release of siderophores or other organic acids that scavenge external Fe(III) and deliver it to the cells. This research investigated the role of siderophores produced by Pseudomonas aeruginosa in the acquisition of Fe(III) from two iron-bearing colloidal nontronites (NAu-1 and NAu-2), comparing differences in bioavailability related with site occupancy and distribution of Fe(III) in the two lattices. To avoid both the direct contact of the mineral colloids with the bacterial cells and the uncontrolled particle aggregation, nontronite suspensions were homogenously dispersed in a porous silica gel before the dissolution experiments. A multiparametric approach coupling UV-vis spectroscopy and spectral decomposition algorithm was implemented to monitor simultaneously the solubilisation of Fe and the production of pyoverdine in microplate-based batch experiments. Both nontronites released Fe in a particle concentration-dependent manner when incubated with the wild-type P. aeruginosa strain, however iron released from NAu-2 was substantially greater than from NAu-1. The profile of organic acids produced in both cases was similar and may not account for the difference in the iron dissolution efficiency. In contrast, a pyoverdine-deficient mutant was unable to mobilize Fe(III) from either nontronite, whereas iron dissolution occurred in abiotic experiments conducted with purified pyoverdine. Overall, our data provide evidence that P. aeruginosa indirectly mobilize Fe from nontronites primarily through the production of pyoverdine. The structural Fe present on the edges of NAu-2 rather than NAu-1 particles appears to be more bio-accessible, indicating that the distribution of Fe, in the tetrahedron and/or in the octahedron sites, governs the solubilisation process. Furthermore, we also revealed that P. aeruginosa could acquire iron when in direct contact with mineral particles in a siderophore-independent manner.

Calcite Dissolution by Brevibacterium sp. SOTI06: A Futuristic Approach for the Reclamation of Calcareous Sodic Soils

“…The growth, planktonic form of biofilm formation and EPS production are the mechanisms by which microorganisms attached to the mineral surface (Banfield et al, 1999; Kraemer, 2004; Peacock et al, 2004; Buss et al, 2007; Yi et al, 2008; Shirvani and Nourbakhsh, 2010; Parrello et al, 2016) and helps dissolution. In the present study, the CDB isolate Brevibacterium sp.…”

Survival and activity of an indigenous iron-reducing microbial community from MX80 bentonite in high temperature / low water environments with relevance to a proposed method of nuclear waste disposal

“…It is well known that fermenting bacteria, such as firmicutes identified in these microbial communities can produce volatile fatty acids (VFAs), which can further interact with metals such as iron (Parrello et al, 2016) and support the growth of other members of the community (Bengtsson et al, 2015;Svensson et al, 2011;Gilmour et al, 2021). This process may have aided in the survival of non-fermenting species in the community in these experiments.…”

“…This process may have aided in the survival of non-fermenting species in the community in these experiments. Possible VFA production, from either carbon in the clay or the breakdown of cell biomass in the inoculum, in addition to the acetate added, may also lead to increases in iron-reduction (Parrello et al, 2016;Bengtsson et al, 2017;Svensson et al, 2011). This iron reduction could in turn could cause a release of silica from iron-containing silicate minerals (Bennett et al, 2001).…”

The mineral weathering ability of Collimonas pratensis PMB3(1) involves a Malleobactin‐mediated iron acquisition system

“…To date, different types of siderophores have been reported and new chelating molecules are continuously discovered (Hernandez et al, 2004;Mathew et al, 2014). Siderophores can impact directly (i.e., surface dissolution) or indirectly (i.e., modification of the solution equilibrium) the mineral weathering process, especially when carbon sources other than glucose are available (i.e., mannitol, trehalose) (Holmén and Casey, 1996;Kraemer, 2004;Parrello et al, 2016;Perez et al, 2019).…”

“…Their role in iron mobilization is clearly demonstrated, but other studies evidenced their role in the chelation of other divalent (Cd2+, Cu2+, Ni2+, Pb2+ and Zn2+) and trivalent cations (Mn3+, Co3+ and Al3+; Visca et al, 1992;Albrecht-Gary and Crumbliss, 1998). Siderophores can impact directly (i.e., surface dissolution) or indirectly (i.e., modification of the solution equilibrium) the weathering process of minerals containing iron and other divalent or trivalent cations, especially when carbon sources other than glucose are available (i.e., mannitol, trehalose; Holmén and Casey, 1996;Kraemer, 2004;Parrello et al, 2016;Perez et al, 2019).…”