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Framboidal pyrite has been a matter of interest of many studies due to its abundance in a wide range of environments, and as a marker of redox conditions. However, the clear origin of framboidal pyrite remains unresolved. The paper discusses the possible role of bacteriophages (bacterial viruses) in the precipitation of sulphide minerals (FeS and CuS) and their impact on the formation of framboid-like structures. Here, two bacteriophages (Enterobacteria phage P1 and Pseudomonas phage Φ6), which differ significantly in the shape and physicochemical properties, were used. Our observations suggest that viruses can attract ions from the solution and thus change the electrochemical properties of precipitated minerals. Moreover, we showed that bacteriophages P1 can lead to the formation of finer mineral particles of FeS and CuS, whereas the framboid-like structures were found only in experiments with precipitation of FeS. However, Pseudomonas phage Φ6 did not cause formation of similar structures probably due to the presence of lipid envelope. Hence, it is assumed that Enterobacteria phage P1 can promote the formation of the FeS-based framboid-like structures. The proposed four-step conceptualized mechanism of the framboidal-like structure synthesis via viruses is as follows: (i) attraction of ions by capsids, (ii) bacteriophages behave like nuclei for mineral crystallisation, (iii) destabilisation of the colloid (ζ-potential ~ 0), (iv) formation of fine agglomerates. |
