The bacteriumPseudomonas aeruginosasenses and gradually responds to interspecific competition for iron

Abstract

Phenotypic plasticity in response to competition is a well-described phenomenon in higher organisms. Here, we show that also bacteria have the ability to sense the presence of competitors and mount fine-tuned responses to match prevailing levels of competition. In our experiments, we studied interspecific competition for iron between the bacterium Pseudomonas aeruginosa (PA) and its competitor Burkholderia cenocepacia (BC). We focused on the ability of PA to phenotypically adjust the production of pyoverdine, an iron-scavenging siderophore. We found that PA upregulates pyoverdine production early on during competition under condition of low iron availability. This plastic upregulation was fine-tuned in response to the level of competition imposed by BC, and seems to confer a relative fitness benefit to PA in the form of an earlier initiation of growth. At later time points, however, PA showed reduced growth in mixed compared to monoculture, suggesting that competitive responses are costly. Altogether, our results demonstrate that phenotypic plasticity in siderophore production plays an important role in interspecific competition for iron. Upregulating siderophore production may be a powerful strategy to lock iron away from competing species, and to reserve this nutrient for strain members possessing the compatible receptor for uptake.

Environmental determinants of pyoverdine production, exploitation and competition in natural Pseudomonas communities

“…For one thing this is because siderophores can be shared between individuals with compatible receptors, which can select for cheating strains that reduce their siderophore investment, yet take up iron by exploiting the siderophores produced by others (West et al, 2006;Jiricny et al, 2010). Conversely, siderophores can also lock iron away from competitors with incompatible receptors, and therefore be involved in inter-strain competition (Buyer and Leong, 1986;Joshi et al, 2006;Butait _ e et al, 2017;Niehus et al, 2017;Schiessl et al, 2017;Leinweber et al, 2018). Finally, siderophores can also bind other heavy metals than iron and thereby contribute to the detoxification of the environment (Petruzzelli, 1989;Braud et al, 2009;Schalk et al, 2011), an alternative social aspect of siderophores that benefits the community as a whole, but is exploitable by non-producers (O'Brien et al, 2014;Hesse et al, 2018).…”

Eisenaufnahme in Pilzen der Gattung Aspergillus: strukturelle und biochemische Einblicke in Siderophoresterasen

“…[25] Angesichts eines essentiellen, aber in hoher Dosis ebenso schädlichen Nährstoffs wie Eisen sind die hochselektive Unterscheidung und der effiziente Abbau verschiedener Substrate entscheidend. Umlagerungen der Untereinheiten und Einschübe in ansonsten hochkonser-vierten Enzymen reichen aus,u md ie Substratspezifitäten drastisch zu beeinflussen, sodass im Rahmen der Konkurrenz verschiedener Spezies sogar Xenosiderophore verstoffwechselt werden kçnnen.…”

“…Umlagerungen der Untereinheiten und Einschübe in ansonsten hochkonser-vierten Enzymen reichen aus,u md ie Substratspezifitäten drastisch zu beeinflussen, sodass im Rahmen der Konkurrenz verschiedener Spezies sogar Xenosiderophore verstoffwechselt werden kçnnen. [25] Angesichts eines essentiellen, aber in hoher Dosis ebenso schädlichen Nährstoffs wie Eisen sind die hochselektive Unterscheidung und der effiziente Abbau verschiedener Substrate entscheidend. Zusammenfassend betrachtet stellen die Siderophor-Freisetzung zu bestimmten Zeitpunkten der Pilzentwicklung, [5,13] die Wiederaufnahme durch spezifische Tr ansporter sowie der darauffolgende Tr ansfer des Eisens in intrazelluläre Depots ein strikt reguliertes Netzwerk dar.…”

Iron Scavenging in Aspergillus Species: Structural and Biochemical Insights into Fungal Siderophore Esterases

“…[25] Regarding an essential but potentially hazardous nutrient like iron, highly selective distinction between and efficient processing of different substrates is crucial. Subunit rearrangements and insertions in otherwise conserved enzymes are sufficient to drastically alter substrate specificity to metabolize even xenosiderophores and foster interspecies competition.…”

“…Subunit rearrangements and insertions in otherwise conserved enzymes are sufficient to drastically alter substrate specificity to metabolize even xenosiderophores and foster interspecies competition. [25] Regarding an essential but potentially hazardous nutrient like iron, highly selective distinction between and efficient processing of different substrates is crucial. Taken together,siderophore release at selective points during fungal development, [5,13] reuptake by specific transporters,a nd subsequent transfer to intracellular iron storage constitute at ightly regulated framework.…”