Cobalamin Protection against Oxidative Stress in the Acidophilic Iron-oxidizing Bacterium Leptospirillum Group II CF-1

Abstract

Members of the genus Leptospirillum are aerobic iron-oxidizing bacteria belonging to the phylum Nitrospira. They are important members of microbial communities that catalyze the biomining of sulfidic ores, thereby solubilizing metal ions. These microorganisms live under extremely acidic and metal-loaded environments and thus must tolerate high concentrations of reactive oxygen species (ROS). Cobalamin (vitamin B12) is a cobalt-containing tetrapyrrole cofactor involved in intramolecular rearrangement reactions and has recently been suggested to be an intracellular antioxidant. In this work, we investigated the effect of the exogenous addition of cobalamin on oxidative stress parameters in Leptospirillum group II strain CF-1. Our results revealed that the external supplementation of cobalamin reduces the levels of intracellular ROSs and the damage to biomolecules, and also stimulates the growth and survival of cells exposed to oxidative stress exerted by ferric ion, hydrogen peroxide, chromate and diamide. Furthermore, exposure of strain CF-1 to oxidative stress elicitors resulted in the transcriptional activation of the cbiA gene encoding CbiA of the cobalamin biosynthetic pathway. Altogether, these data suggest that cobalamin plays an important role in redox protection of Leptospirillum strain CF-1, supporting survival of this microorganism under extremely oxidative environmental conditions. Understanding the mechanisms underlying the protective effect of cobalamin against oxidative stress may help to develop strategies to make biomining processes more effective.

Predominance of deterministic microbial community dynamics in salterns exposed to different light intensities

“…Genes related to the biosynthesis of compounds such as glutathione that can hamper oxidative damage under osmotic stress (Smirnova and Oktyabrsky, 2005), and ergothioneine, an amino acid with antioxidant and cytoprotective capabilities against cellular stressors (Cheah and Halliwell, 2012), were also detected in increased abundances. Furthermore, we observed an increase in genes related to cobalamin, which can contribute to the reduction of the intracellular levels of ROSs (reactive oxygen species and oxidative stress) and the damage of biomolecules, enhancing cell survival when exposed to oxidative stress (Ferrer et al, 2016). Finally, the sudden light exposure (shade removal) promoted a rapid increase in genes involved in the UvrABC system (genes related to DNA repair).…”

Visible Light‐Induced Radical Mediated DNA Damage

“…). Cobalamins are known radical scavengers ; therefore, generated will be scavenged by cobalamin before the addition of the DNA. As expected, no DNA cleavage was observed for this experiment.…”

Nutritional inter-dependencies and a carbazole-dioxygenase are key elements of a bacterial consortium relying on aSphingomonasfor the degradation of the fungicide thiabendazole

“…MAG 3X21F, showing up-regulation of several stress-related genes when grown on TBZ (39 genes), a pattern often observed in pollutant-degrading bacteria during exposure to the target pollutant [104–106], Hydrogenophaga 23F was the only other MAG that mobilized a stress response, involving the up-regulation of a general stress response gene and a glutathione-S-transferase gene (locus tag: Bin_23F_Hydrogenophaga_01167/03148). Oxidative stress elicitors have been shown to stimulate cobalamin production in bacteria [107]. Yet, this would also fail to explain on its own the specificity of the interaction, unless there are pronounced metabolic and functional differences among Hydrogenophaga consortium members, previously reported for Hydrogenophaga isolates [108], which enable this specialized interaction to occur.…”