Experimental studies on the role of bacteriophages in the formation of carbonates and sulphides

Bacteriophages are abundant in all environments on the Earth. However, their impact on mineral formation remains undiscovered. In our experimental approach, two distinctly different bacteriophages (Pseudomonas phage Φ6 and Escherichia phage P1) were used to assess their influence on mineral formation. Here, we focus on the formation of carbonates and sulfides.

Bacteriophages are supposed to influence carbonate precipitation. We demonstrated that bacteriophages induce the formation of regular ‘viral-like’ mineral particles. These particles were strongly aggregated, while such phenomena did not occur in the control sample. Moreover, bacteriophages induced the formation of vaterite (an unstable form of calcium carbonate), which remained stable for a longer time. 

The origin of framboidal pyrite is an important issue from the point of view of the precipitation of sulfide minerals. It is assumed that ions present in the solution can be bound by bacteriophages and thus influence mineral precipitation. We postulated that bacteriophages might be one of the factors that induce the precipitation of finer mineral particles, which can then be formed into framboid-like structures. 

It seems that bacteriophages may play a crucial role in the precipitation of various minerals. In our research, for both minerals, similar phenomena occurred: (i) change in the shape of mineral particles; (ii) occurrence of aggregation/agglomeration in the presence of bacteriophages; (iii) change in the size of agglomerates/aggregates. Moreover, XRD patterns were different for carbonates precipitated in the presence of bacteriophages. However, such differences were not visible for sulfides, probably due to the strong oxidation caused by the difficulties in maintaining the samples.