Scientists have added cadmium to bacteria [bbc.com], causing them to accumulate cadmium sulphide crystals on their surfaces:
Scientists have created bacteria covered in tiny semiconductors that generate a potential fuel source from sunlight, carbon dioxide and water. The so-called "cyborg" bugs produce acetic acid, a chemical that can then be turned into fuel and plastic. In lab experiments, the bacteria proved much more efficient at harvesting sunlight than plants. The work was presented at the American Chemical Society meeting [acs.org] in Washington.
[...] These newly boosted bacteria produce acetic acid, essentially vinegar, from CO2, water and light. They have an efficiency of around 80%, which is four times the level of commercial solar panels, and more than six times the level of chlorophyll.
Also at IEEE [ieee.org].