Calcium complexes microbes

The prerequisite for the toxic effect of heavy metals is penetration of the cell wall. For this, certain carriers are needed to transport the heavy metals through lipophilic centres in the cell membrane. Oxines, 2-mercapto-pyridine-N-oxides (III. 11) and dialkyl-dithiocarbamates (III.9) are examples of compounds capable of complexing heavy metal ions such as Cu ions and transporting them into the microbe cell. The carriers named are also toxic, as such, to micro-organisms. But, as a copper carrier, copper-8-hydroxyquinoline is about 100 times more effective than 8-hydroxyquinoline (oxine III. 11.4). Once heavy metal ions have overcome the cell wall with the aid of the carrier molecules, they may compete with magnesium, calcium and potassium ions for receptor sites, inhibit enzymes and cause non-specific precipitation of proteins. 

Reefs are underwater oases of complexity and life, and they concentrate the elements useful for life. Many species can find niches for protection and opportunity in the calcium-based nooks and crannies. Phosphorus is also concentrated at the reefs, in some cases by microbes that live symbiotically inside the sponges there. These microbes collect phosphorus as granules that then support the rest of the complex web of life. 

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