Quantitative Proteomic Analysis of Cyanide and Mercury Detoxification by Pseudomonas pseudoalcaligenes CECT 5344

Abstract

Cyanide, mercury, and arsenic are considered very toxic chemicals that are present in nature as cocontaminants in the liquid residues generated by different industrial activities like mining. Considering the huge amounts of toxic cyanide- and mercury-containing wastes generated at a large scale and the high biotechnological potential of P. pseudoalcaligenes CECT 5344 in the detoxification of cyanide present in these industrial wastes, in this work, proteomic, transcriptional, and bioinformatic approaches were used to characterize the molecular response of this bacterium to cyanide and mercury, highlighting the mechanisms involved in the simultaneous detoxification of both compounds.

Bacterial tolerance and detoxification of cyanide, arsenic and heavy metals: Holistic approaches applied to bioremediation of industrial complex wastes

“…In the presence of cyanide, weak cadmium-cyanide complexes may be formed, and this could contribute to lowering cyanide toxicity, as recently described for mercury and cyanide when they are present simultaneously in the culture media of P. pseudoalcaligenes CECT 5344 (Biełło, Olaya-Abril, et al, 2023).…”

“…Therefore, the chemical formation of mercury-cyanide complexes could contribute to decrease the toxicity displayed by both free cyanide and mercury. A quantitative proteomic analysis has been also applied in P. pseudoalcaligenes CECT 5344 to study mercury tolerance in the presence of cyanide (Biełło, Olaya-Abril, et al, 2023). This study revealed the induction of a glutathione S-transferase, which is possibly related to the cellular mechanism of mercury detoxification (Bjørklund et al, 2019).…”

“…In a bioreactor, the strain CECT 5344 was able to detoxify a jewellery waste containing up to 12 mM total cyanide (free and complexed to metals) (Ibáñez et al., 2017 ). The strain CECT 5344 can also grow in batch cultures with cyanide in the presence of high concentrations of arsenic or mercury (Biełło, Cabello, et al., 2023 , Biełło, Olaya‐Abril, et al., 2023 ). Other bacteria that can degrade metal‐cyanide complexes, including those with zinc, nickel, copper, silver and iron, have been also described (Dimitrova et al., 2020 ; Patil & Paknikar, 2000 ; Silva‐Avalos et al., 1990 ).…”

“…The RND‐based efflux systems are composed of protein complexes that span the whole cell wall of Gram‐negative bacteria, and they include heavy metal extruder (HME) members, among others. However, the best‐characterized mercury resistance mechanism is encoded by the mer operon, which encodes enzymes that transform mercurials into less toxic or volatile forms (Biełło, Olaya‐Abril, et al., 2023 ; Sone et al., 2013 ) (Figure 3 ). Two types of mer gene clusters have been described, showing a narrow spectrum if they only act on inorganic mercury, or a broad spectrum if they are able to use both inorganic and organomercurial forms (Mergeay et al., 2003 ; Osborn et al., 1997 ).…”

“…In this sense, different bacteria have been described to be able to resist and degrade elevated concentrations of cyanide, metals and metalloids. In the development of a process for bioremediation of these toxic wastewaters it must be considered the possible interactions of microorganisms with metals and cyanide, the formation of different cyano‐derivatives and the catalysed and non‐catalysed reactions initiated by the reactivity of cyanide with other molecules (Biełło, Cabello, et al., 2023 , Biełło, Olaya‐Abril, et al., 2023 ; Luque‐Almagro et al., 2016 ; Newsome & Falagán, 2021 ).…”