Siderophore production in Azotobacter vinelandii in response to Fe‐, Mo‐ and V‐limitation

Abstract

Azotobacter vinelandii is a terrestrial diazotroph well studied for its siderophore production capacity and its role as a model nitrogen fixer. In addition to Fe, A. vinelandii siderophores are used for the acquisition of the nitrogenase co-factors Mo and V. However, regulation of siderophore production by Mo- and V-limitation has been difficult to confirm and knowledge of the full suite of siderophores synthesized by this organism has only recently become available. Using this new information, we conducted an extensive study of siderophore production in N -fixing A. vinelandii under a variety of trace metal conditions. Our results show that under Fe-limitation the production of all siderophores increases, while under Mo-limitation only catechol siderophore production is increased, with the strongest response seen in protochelin. We also find that the newly discovered A. vinelandii siderophore vibrioferrin is almost completely repressed under Mo- and V-limitation. An examination of the potential nitrogen 'cost' of siderophore production reveals that investments in siderophore N can represent as much as 35% of fixed N, with substantial differences between cultures using the Mo- as opposed to the less efficient V-nitrogenase.

Comparison of five bacterial strains producing siderophores with ability to chelate iron under alkaline conditions

“…Several siderophores have been described for A. vinelandii , namely azotobactin, previously known as yellow-green fluorescent peptide (Bulen and LeComte 1962), 2,3-dihydroxybenzoic acid, azotochelin (Corbin and Bulen 1969), aminochelin (Page and Tigerstrom 1988) and protochelin (Cornish and Page 1995), which are, respectively, mono-, mono-, di-, mono- and tri-catecholates. Vibrioferrin, another siderophore described (McRose et al 2017), has two hydroxy-carboxylate moieties which should not react in Csaky and Arnow tests. Finally, azotobactin has a complex structure in which a catechol and a hydroxamate moieties can be found (Duhme et al 1998).…”

Iron Homeostasis in Bacillus subtilis Requires Siderophore Production and Biofilm Formation

“…Static cultures face challenges, such as the distance between cells and Fe sources, the diffusion of siderophores and Fe-siderophore complexes in the medium, that shaken cultures do not encounter. Many studies on Fe homeostasis and siderophore-mediated acquisition of Fe by soil bacteria have been performed in shaken cultures (28, 29). Thus, the importance of the interplay between siderophore production and extracellular matrix production to support efficient Fe acquisition and Fe homeostasis might have been overlooked.…”

Promising bacterial genera for agricultural practices: An insight on plant growth-promoting properties and microbial safety aspects

“…Usually, hydroxamates are more commonly found in neutral to acid environments while catecholates are more commonly found in neutral to alkaline environments (Saha et al, 2013). Several bacterial genera were described to produce siderophores, such as Azotobacter (Baars et al, 2016;McRose et al, 2017;Romero-Perdomo et al, 2017), Azospirillum (Banik et al, 2016), Bacillus (Kesaulya et al, 2018;Pourbabaee et al, 2018), Dickeya (Sandy and Butler, 2011), Klebsiella (Bailey et al, 2018;Zhang et al, 2017), Nocardia (Hoshino et al, 2011), Pantoea (Burbank et al, 2015;Soutar and Stavrinides, 2018), Paenibacillus (Liu et al, 2017), Pseudomonas (Baune et al, 2017;Deori et al, 2018;Pourbabaee et al, 2018), Serratia (Coulthurst, 2014) and Streptomyces (Gáll et al, 2016;Goudjal et al, 2016;Schütze et al, 2014).…”

“…Azotobacter strains are also known to form resistant cysts during dormant phases or when exposed to some reagents (Diaz-Barrera and Soto, 2010). This genus is of great importance to the environment due to their great nitrogen fixation capacity, which is achieved as a consequence of the high metabolic rate of the three nitrogenases (McRose et al, 2017).…”

“…More recently, in a broad genetic study on Azotobacter vinelandii, vibrioferrin was hinted, opening the possibility that one more siderophore is produced by Azotobacter vinelandii (Baars et al, 2016). Vibrioferrin was later described to be regulated by vanadium and molybdenum levels of culture medium (McRose et al, 2017).…”