The DNA-binding protein from stationary phase (Dps) protein family plays an important role in protecting microorganisms from oxidative and nutritional stresses. In silico analysis of the promoter region of alr3808, a dpsA homologue from the cyanobacterium Nostoc sp. PCC7120 shows putative ironboxes with high homology with those recognized by FurA (ferric uptake regulator). Evidence for the modulation of dpsA by FurA was obtained using in vitro and in vivo approaches. SELEX linked to PCR was used to identify P dpsA as a FurA target. Concurrently, EMSA assays showed high affinity of FurA for the dpsA promoter region. DpsA expression analysis in an insertional mutant of the alr1690-afurA message (that exhibited an increased expression of FurA) showed a reduced synthesis of DpsA. These studies suggest that FurA plays a significant role in the regulation of the DpsA.

A bacterial strain (DE2008) was isolated from a consortium of microorganisms living in the microbial mats of the Ebro Delta with the ability to grow under conditions of high concentrations of lead and copper. Strain DE2008 has been characterized by microscopic and metabolic techniques and identified by sequencing of PCR-amplified 16S rRNA gene fragments as Micrococcus luteus. The strain is highly resistant to lead and copper. Micrococcus luteus DE2008 grew optimally until levels of 1 mM of Pb (NO 3 ) 2 and CuSO 4 , respectively, and was completely inhibited at 3 mM Pb(NO 3 ) 2 and at 1.5 mM CuSO 4 . Elemental analysis determined by energy-dispersive X-ray spectroscopy (EDX) coupled with scanning electron microscopy and transmission electron microscopy from polluted cultures of DE2008 show that this microorganism can biosorpt Pb and Cu in exopolysaccharide envelopes, without accumulating them inside the cells.

Integrons are bacterial genetic elements known to be active vectors of antibiotic resistance among clinical bacteria. They are also found in bacterial communities from natural environments. Although integrons have become especially efficient for bacterial adaptation in the particular context of antibiotic usage, their role in natural environments in other contexts is still unknown. Indeed, most studies have focused on integrons and the spread of antibiotic resistance in freshwater or soil impacted by anthropogenic activities, with only few on marine environments. Notably, integrons show a wider diversity of both gene cassettes and integrase gene in natural environments than in clinical environments, suggesting a general role of integrons in bacterial adaptation. This article reviews the current knowledge on integrons in marine environments. We also present conclusions of our studies on polluted and nonpolluted backgrounds.