Modern nodules: mineralogical investigation and modelling experiments. Part 2. Experiments on carbonate deposition by bacterial communities

In the article the results of set of experiments on bacterial natural and laboratory carbonate deposition are presented. In the experiment №1 we revealed the most favorable for the deposition of CaCO3 nutrient medium and established the morphology of neo-formed crystals and micronodules. Experiment №2 demonstrated that the bacterial communities and isolates deposited calcite in the form of split crystals and aggregates of dumbell-like or globular shape. The main task of the experiment 3 and 4 was to study bacterial carbonates obtained by increasing the magnesium content in the nutrient medium and adding of manganese chloride. The mineral phase (bioinoculants and new formations) were studied by a complex of physical methods. Our data support the hypothesis of bacterial origin of natural calcite formations in caves.