Mechanism of energy metabolism for adapted Acidithiobacillus ferrooxidans to copper resistance

This article aimed to elucidate the mechanism of energy metabolism for copper resistance in adapted Acidithiobacillus ferrooxidans. Initially, during batch cultivation process, ferrous oxidation (Fe2+), bacteria growth, intracellular energy charge status, polyphosphate kinase (PPK) activiy, and inorganic polyphosphate (polyP) accumulation were compared between adapted and unadapted strains. Then, in the presence of copper stress, the dynamic changes of polyP levels and exopolyphosphatase (PPX) activity were investigated. Furthermore, accumulation of copper ions inside the cell was determined. Results showed that medium Fe2+ was exhausted at 72 h and 96 h in batch culture adapted and unadapted A. ferrooxidans and a relatively higher total protein level, energy charge, PPK activiy, and polyP content was observed in adapted strain. As subjected to 50 mmol/L copper ion stress, intracellular polyP decreased to the lowest level at 8 h and 14 h after shift-time and corresponding PPK activiy increased to 443 and 276 U/mg protein, respectivly, in adapted and unadapted A. ferrooxidans, indicating much energy was released from polyP degradation. As a result, intracellular copper ion was kept at a very lowered level in adatped strain. It was suggested that an efficeint energy supply system existed that contributes to transporting intracelualr copper ion out of cell during active process in adapted A. ferrooxidans. (c) 2018 American Institute of Chemical Engineers Environ Prog, 38:e13054, 2019