The document summarizes a study that used natural transformation to create gene knockouts in the green sulfur bacterium Chlorobium tepidum. The study demonstrated that C. tepidum is naturally transformable and can be used to inactivate genes via homologous recombination. Specifically, the researchers inactivated the nifD gene involved in nitrogen fixation to validate the method. Over 30 genes have been inactivated using this approach to study various metabolic pathways in C. tepidum.