Marion Jespersen in the lab. (IMAGE) Max Planck Institute for Marine Microbiology Caption Marion Jespersen with the purified F420-dependent sulfite reductase (Fsr). The black colour comes from all the iron involved in the reaction. Experiments are carried out in an anaerobic chamber and under artificial light to protect the enzyme from oxygen and daylight. Credit Tristan Wagner/Max Planck Institute for Marine Microbiology Usage Restrictions Only to be used in the context of this publication and citing the correct copyright. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.