What is the importance of purple non sulfur bacteria?

The understanding of some of the most fundamental processes of life, such as the photosynthetic generation of cellular energy, or the metabolic fixation of carbon dioxide and nitrogen, has been driven largely by investigating a unique group of photosynthetic bacterial organisms, the purple non-sulfur bacteria (Rhodospirillaceae).  Specifically, these bacteria have been extensively employed for studying principles of photosynthetic and respiratory electron transport, and more recently, for investigating the regulation of gene expression in response to reduction-oxygenation (redox) signals.