Poly-gamma-glutamic acid secretion protects Bacillus subtilis from zinc and copper intoxication

Zinc and copper are essential micronutrients that serve as a cofactors for numerous enzymes. However, when present at elevated concentrations, zinc and copper are highly toxic to bacteria. To combat the effects of zinc and copper excess, bacteria have evolved a wide array of defense mechanisms. Here, we show that the Gram positive soil bacterium, Bacillus subtilis, produces the extracellular polymeric substance, poly-gamma-glutamate (γ-PGA) as a protective mechanism in response to zinc and copper excess. Furthermore, we provide evidence that zinc and copper dependent γ-PGA production is independent of the DegS-DegQ two component regulatory system and likely occurs at a post-transcriptional level. These data provide new insight into bacterial metal resistance mechanisms and contribute to our understanding of the regulation of bacterial γ-PGA biosynthesis.ImportanceZinc and copper are potent antimicrobial compounds. As such, bacteria have evolved a diverse range of tools to prevent metal intoxication. Here, we show that the Gram-positive model organism, Bacillus subtilis, produces poly-gamma-glutamic acid (γ-PGA) as a protective mechanism against zinc and copper intoxication and that zinc and copper dependent γ-PGA production occurs by a yet undefined mechanism independent of known γ-PGA regulation pathways.

Chronic Copper Sulfate Poisoning

Copper, as a salt, is toxic and has the potential to harm multiple organs. Copper intoxication causes intravascular haemolysis followed by liver and kidney failure that can be fatal. We present a case of chronic copper sulfate poisoning in a 66-year-old man with dysphagia to solids and liquids, anaemia, acute kidney injury, liver cytolysis and hypocalcaemia. The patient improved with supportive care, but chronic kidney disease was established. Anamnesis was crucial for the diagnosis, given the non-specific signs and symptoms. The history of chronic exposure to pest treatment with a blue dust cloud made us suspect copper sulfate poisoning.

She Has The Blues: An Unusual Case of Copper Sulphate Intoxication

Background: Copper is an essential trace element of the human body. However, it is related to many diseases. Copper intoxication is not common in Western countries, but needs to be rapidly recognised because of its high lethality. Case presentation: We report the case of a 40-year-old woman who presented to the emergency department after performing intrarectal administration of a blue powder sent from Cameroon by her family, in the belief that this would help her to get pregnant. Her evolution was complicated by multiorgan failure and the unusual circumstances. The diagnosis was suspected on the basis of the clinical presentation and the colour of the powder, and confirmed by blood dosage and toxicological analysis of the powder. She underwent symptomatic treatment, and the outcome was progressively favourable, apart from persistent chronic renal failure with dependence on dialysis. Conclusion: Copper intoxications are rare but severe. Laboratory diagnosis of the condition is not an issue; the difficulty is suspecting it and quickly initiating chelation treatment associated with symptomatic treatments.

The effect of copper on the abundance, cell morphology and content of photosynthetic pigments in the microalga Porphyridium purpureum

Red microalga Porphyridium purpureum adaptive abilities to copper intoxication were studied. Cell number dynamics and morphology, contents of chlorophyll a and carotenoids were used as test-points. The experiment was conducted in two stages. At the first stage the effect of copper in concentrations of 50 and 100 µg·l−1 was studied; at the second stage the alga adaptive abilities to growth in copper contaminated medium were assessed. At the first stage copper concentration of 50 µg·l−1 didn’t influence the parameters under study. Addition of 100 µg·l−1 caused growth inhibition and photosynthetic pigment content decrease. At the second stage after transferring alga to a medium with 50 µg·l−1 copper concentration from a medium with similar conditions, cell number and photosynthetic pigment content were not significantly different from the control ones. Part of the cells deformed, chloroplasts became darkened. Transferring to a medium with 100 µg·l−1 from a medium with 50 µg·l−1 copper concentration caused growth delay; most of the cells in suspension were with dark, granulated chloroplast. Cells transferring from a medium with 100 µg·l−1 to a medium with the same concentration resulted in growth inhibition and photosynthetic pigment content decrease. Part of the cells in suspension became lager than in control and with great amount of mucilage. Complete adaptation of P. purpureum to copper intoxication didn’t occur.

Copper intoxication inhibits aerobic nucleotide synthesis in Streptococcus pneumoniae

Graphical model of copper export and toxicity in S. pneumoniae.