# Bioremediation and Recovery of Lead and Cadmium by Spores of Bacillus subtilis C1

## TL;DR

Bacillus subtilis spores can detoxify water by absorbing lead and cadmium, and restore plant growth in contaminated water.

## Contribution

Bacillus subtilis C1 spores show high efficiency in adsorbing and recovering heavy metals without losing functionality.

## Key findings

- Bacillus subtilis C1 spores efficiently adsorb lead and cadmium.
- Spore-adsorbed metals can be released by disrupting the spore coat.
- C1 spores restore plant growth in cadmium-polluted water.

## Abstract

Spores of a hot spring isolated strain of Bacillus subtilis were tested as a biotechnological tool to be used for the detoxification and bioremedition of heavy metals. Lead and cadmium were efficiently adsorbed by B. subtilis spores with those of C1 more efficient than those of the lab collection strain PY79. Metal‐adsorption did not alter the functionality of C1 spores that were still fully resistant to heat, ethanol or chloroform and able to germinate after the interaction with Cd2+ or Pb2+. The spore‐adsorbed metals were released upon disruption of the spore coat layers, suggesting that the metals were mostly accumulated within the spore coat. Heat‐inactivated spores released almost all adsorbed metals, allowing the recovery of Cd2+ and Pb2+. While Cd2+ polluted water impaired the normal germination and growth of seeds of the model plant Arabidopsis thaliana, treatment of the polluted water with C1 spores restored plant growth.

This study proposes the spore of B. subtilis C1 as an efficient detoxification and bioremediation tool. Efficacy of the spore‐based decontamination was tested in vivo with A. thaliana seeds. Plant growth was affected by Cd2+, but this effect was totally abolished when the contaminated water was treated with C1 spores. The spore‐adsorbed metals can also be efficiently released by either a chemical or physical treatment.