Environmental Adaptability and Quorum Sensing: Iron Uptake Regulation during Biofilm Formation by Paracoccus denitrificans

Abstract

is a valuable model organism due to its versatile respiration capability and bioenergetic flexibility, both of which are critical to its survival in different environments. Quorum sensing (QS) plays a crucial role in the regulation of many cell functions; however, whether QS systems play a role in is unknown. In this study, we demonstrated that iron uptake systems in were directly regulated by a newly identified QS system. Genes coding for TonB-dependent systems, which transport chelated iron, were transcribed at higher levels in the QS-defective mutants. In contrast, genes coding for the Fbp system, which is TonB independent and transports unchelated ferric iron, were downregulated in the mutants. In brief, QS in triggers a switch in iron uptake from TonB-dependent to TonB-independent transport during biofilm formation as higher concentrations of iron accumulate in the exopolysaccharide (EPS). Switching from TonB-dependent iron uptake systems to TonB-independent systems not only prevents cells from absorbing excess iron but also conserves energy. Our data suggest that iron uptake strategies are directly regulated by QS in to support their survival in available ecological niches. As iron is an important trace metal for most organisms, its absorption is highly regulated. Fur has been reported as a prevalent regulator of iron acquisition. In addition, there is a relationship between QS and iron acquisition in pathogenic microbes. However, there have been few studies on the iron uptake strategies of nonpathogenic bacteria. In this study, we demonstrated that iron uptake systems in PD1222 were regulated by a newly identified PdeR/PdeI QS system during biofilm formation, and we put forward a hypothesis that QS-dependent iron uptake systems benefit the stability of biofilms. This report elaborates the correlation among QS, iron uptake, and biofilm formation and thus contributes to an understanding of the ecological behavior of environmental bacteria.

Experimental metatranscriptomics reveals the costs and benefits of dissolved organic matter photo‐alteration for freshwater microbes

“…The inner membrane proteins tonB and exbB (along with exbD) transduce proton motive force to TonB‐dependent transporters in the outer membrane that bind and transport chelated Fe(III) including siderophore‐bound Fe(III). In contrast, TonB‐independent systems transport unchelated Fe(III) across the inner membrane after it crosses the outer membrane either passively or via some unknown outer membrane system (Wyckoff et al ., 2006; Zhang et al ., 2018). This suggests that dark‐treatment microbes were importing chelated Fe(III) and light‐treatment microbes were importing unchelated Fe(III).…”

YdiV regulates Escherichia coli ferric uptake by manipulating the DNA-binding ability of Fur in a SlyD-dependent manner

“…It has been reported that autoinducer-1 stimulates ydiV expression in an sdiA -dependent manner ( 77 ). Strikingly, a Pseudomonas quinolone signal (PQS), which acts as an iron chelator, upregulates a number of genes for iron acquisition and the oxidative stress response ( 78 , 79 ). These studies imply the possible involvement of a quorum-sensing system in YdiV-Fur-SlyD-dependent iron regulation in E. coli .…”

Novel Strategy for Improvement of the Bioleaching Efficiency of Acidithiobacillus ferrooxidans Based on the AfeI/R Quorum Sensing System

“…Overexpression of qs-I gene operon caused the upregulation of tonB (AFE_1991) and orpD (AFE_1497) genes transcription ( Table 2). tonB and orpD genes involved in the transportation of EPS secretions have been reported [59]. Therefore, qs-I regulated EPS synthesis and biofilm formation by regulating the synthesis and secretion of EPS in A. ferrooxidans.…”