Vibrio Iron Transport: Evolutionary Adaptation to Life in Multiple Environments

Abstract

SUMMARYIron is an essential element forVibriospp., but the acquisition of iron is complicated by its tendency to form insoluble ferric complexes in nature and its association with high-affinity iron-binding proteins in the host. Vibrios occupy a variety of different niches, and each of these niches presents particular challenges for acquiring sufficient iron.Vibriospecies have evolved a wide array of iron transport systems that allow the bacteria to compete for this essential element in each of its habitats. These systems include the secretion and uptake of high-affinity iron-binding compounds (siderophores) as well as transport systems for iron bound to host complexes. Transporters for ferric and ferrous iron not complexed to siderophores are also common toVibriospecies. Some of the genes encoding these systems show evidence of horizontal transmission, and the ability to acquire and incorporate additional iron transport systems may have allowedVibriospecies to more rapidly adapt to new environmental niches. While too little iron prevents growth of the bacteria, too much can be lethal. The appropriate balance is maintained in vibrios through complex regulatory networks involving transcriptional repressors and activators and small RNAs (sRNAs) that act posttranscriptionally. Examination of the number and variety of iron transport systems found inVibriospp. offers insights into how this group of bacteria has adapted to such a wide range of habitats.

Saharan dust nutrients promote Vibrio bloom formation in marine surface waters

“…Vibrio growth in natural seawater continued even at the highest Dust SIM -Fe additions (836 nM), suggesting increasing Fe limitation, which was unexpected (34). Although the bioavailable fraction of Fe added to the microcosms was likely reduced because of rapid oxidation and precipitation due physiochemical factors in natural seawater (17), Vibrio physiology suggests a high Fe demand with up to 5 μM needed for replete growth (12). Growth rates in Vibrio are among the fastest known of any bacteria, with doublings every 8-9 min recorded in some species (5).…”

“…V. cholerae, which is arguably the most studied of the Vibrio species and has a very well characterized genome, has >50 Fe acquisition genes spread across its two chromosomes for ferrous, ferric, and biologically complexed Fe uptake (12). This genetic repertoire suggests that Vibrio are effective competitors for Fe in many different environmental niches.…”

“…Iron (Fe) is an essential micronutrient for Vibrio growth in the environment as well as during host invasion, where it is actively sequestered by the host to prevent bacterial colonization (9). Vibrio have evolved to be adept scavengers of Fe in a variety of conditions (12). Despite the importance of Fe for growth, there has been little characterization of the effects of environmental Fe enrichment on Vibrio population dynamics and the role of these bacteria in Fe cycling in marine systems.…”

Synthesis and Structural Analysis of Novel Norspermidine Derivatives

“…The NMR spectra were measured with a Varian Gemini 300VT spectrometer, operating at 300.07 and 75.4614 MHz for 1 H and 13 C, respectively. Typical conditions for the proton spectra were: pulse width 32˚, acquisition time 5s, FT size 32 K and digital resolution 0.3 Hz per point, and for the carbon spectra pulse width 60˚, FT size 60 K and digital resolution 0.6 Hz per point, the number of scans varied from 1200 to 10,000 per spectrum.…”

“…However, it must be also noted that norspermidine can promote biofilm formation in case of Vibrio cholerae [13]. The ambiwalent character of norspermidine towards inhibition or formation of biofilms is the subject of a vigorous dispute in the literature [6] [7] [14]- [21].…”