Ag analysis by atomic absorption spectrometry
To analyze the concentration of silver precipitated on the cells and in the supernatant, biomass and supernatant were boiled for 2 h with 65% HNO3 (Normapur, VWR, Belgium) and 30% H2O2 (Merck, Germany) until the sample was clear. Subsequently, the silver concentration was measured using a Shimadzu AA-6300 atomic absorption spectroscope (Japan).