Purple bacteria photo-bioelectrochemistry: enthralling challenges and opportunities

Purple non-sulfur bacteria are anoxygenic photosynthetic microorganisms characterized by an extremely versatile metabolism, allowing them to grow in a broad variety of conditions as well as in the presence of different contaminants. This characteristic motivates the interest in their employment in photo-bioelectrochemical systems applicable in environments with dynamic physico-chemical properties. While the photochemistry of purple bacteria has been intensively studied, their photo-bioelectrochemistry and extracellular electron transfer process with an electrode surface remain largely unexplored. Herein, the process of harvesting electrons from intact purple bacteria is reviewed, and the perspective of enthralling future research possibilities is presented, placing emphasis on the major challenges in the photo-bioelectrochemistry of purple bacteria.