Proteomic and morphological insights into the exposure of Cupriavidus metallidurans CH34 planktonic cells and biofilms to aluminium.

Aluminium (Al) is one of the most popular materials for industrial and domestic use. Nevertheless, research has proven that this metal can be toxic to most organisms. This light metal has no known biological function and to date very few aluminium-specific biological pathways have been identified. In addition, information about the impact of this metal on microbial life is scarce. Here, we aimed to study the effect of aluminium on the metal-resistant soil bacterium Cupriavidus metallidurans CH34 in different growth modes, i.e. planktonic cells, adhered cells and mature biofilms. Our results indicated that despite a significant tolerance to aluminium (minimal inhibitory concentration of 6.25 mM Al2(SO4)3.18H2O), the exposure of C. metallidurans to a sub-inhibitory dose (0.78 mM) caused early oxidative stress and an increase in hydrolytic activity. Changes in the outer membrane surface of planktonic cells were observed, in addition to a rapid disruption of mature biofilms. On protein level, aluminium exposure increased the expression of proteins involved in metabolic activity such as pyruvate kinase, formate dehydrogenase and poly(3-hydroxybutyrate) polymerase, whereas proteins involved in chemotaxis, and the production and transport of iron scavenging siderophores were significantly downregulated.

Growth and biofilm formation of Cupriavidus metallidurans CH34 on different metallic and polymeric materials used in spaceflight applications.

Bacteria biofilm formation and its complications are of special concern in isolated structures, such as offshore stations, manned submarines and space habitats, as maintenance and technical support are poorly accessible due to costs and/or logistical challenges. In addition, considering that future exploration missions are planned to adventure farther and longer in space, unlocking biofilm formation mechanisms and developing new antifouling solutions are key goals in order to ensure spacecraft's efficiency, crew's safety and mission success. In this work, we explored the interactions between Cupriavidus metallidurans, a prevalently identified contaminant onboard the International Space Station, and aerospace grade materials such as the titanium alloy TiAl6V4, the stainless steel AISI 316 (SS316) and Polytetrafluoroethylene (PTFE) or Teflon. Borosilicate glass was used as a control and all surfaces were investigated at two different pH values (5.0 and 7.0). Biofilms were almost absent on stainless steel and the titanium alloy contrary to Teflon and glass that were covered by an extensive biofilm formed via monolayers of scattered matrix-free cells and complex multilayered clusters or communities. Filamentous extracellular DNA structures were observed specifically in the complex multilayered clusters adherent to Teflon, indicating that the employed attachment machinery might depend on the physicochemical characteristics of the surface.

Metal-Organic Frameworks as Efficient Oral Detoxifying Agents.

Poisoning and accidental oral intoxication are major health problems worldwide. Considering the insufficient efficacy of the currently available detoxification treatments, a pioneering oral detoxifying adsorbent agent based on a single biocompatible metal-organic framework (MOF) is here proposed for the efficient decontamination of drugs commonly implicated in accidental or voluntary poisoning. Furthermore, the in vivo toxicity and biodistribution of a MOF via oral administration have been investigated for the first time. Orally administered upon a salicylate overdose, this MOF is able to reduce the salicylate gastrointestinal absorption and toxicity more than 40-fold (avoiding histological damage) while exhibiting exceptional gastrointestinal stability (<9% degradation), poor intestinal permeation, and safety.