General Chapters: Sulfate Activation and Reduction, Biosynthesis of Sulfur Containing Amino Acids -- to Sulfur Metabolism in Phototrophic Organisms -- Uptake, Distribution and Subcellular Transport of Sulfate -- Phylogenetic Analysis of Sulfate Assimilation and Cysteine Biosynthesis in Phototrophic Organisms -- Metabolism of Cysteine in Plants and Phototrophic Bacteria -- Metabolism of Methionine in Plants and Phototrophic Bacteria -- Sulfotransferases from Plants, Algae and Phototrophic Bacteria -- Cysteine Desulfurase-Mediated Sulfur Donation Pathways in Plants and Phototrophic Bacteria -- Sulfur in Plants and Algae -- Molecular Biology and Functional Genomics for Identification of Regulatory Networks of Plant Sulfate Uptake and Assimilatory Metabolism -- Biosynthesis, Compartmentation and Cellular Functions of Glutathione in Plant Cells -- Sulfolipid Biosynthesis and Function in Plants -- Sulfur-Containing Secondary Metabolites and Their Role in Plant Defense -- Sulfite Oxidation in Plants -- The State of Sulfur Metabolism in Algae: From Ecology to Genomics -- Sulfur in Phototrophic Prokaryotes -- Systematics of Anoxygenic Phototrophic Bacteria -- Inorganic Sulfur Compounds as Electron Donors in Purple Sulfur Bacteria -- Sulfide Oxidation from Cyanobacteria to Humans: Sulfide-Quinone Oxidoreductase (SQR) -- Genomic Insights into the Sulfur Metabolism of Phototrophic Green Sulfur Bacteria -- Genetic and Proteomic Studies of Sulfur Oxidation in Chlorobium tepidum (syn. Chlorobaculum tepidum) -- Ecology and Biotechnology -- Ecology of Phototrophic Sulfur Bacteria -- Role of Sulfur for Algae: Acquisition, Metabolism, Ecology and Evolution -- Role of Sulfur for Plant Production in Agricultural and Natural Ecosystems -- Using Anoxygenic Photosynthetic Bacteria for the Removal of Sulfide from Wastewater -- Specific Methods -- X-ray Absorption Spectroscopy as Tool for the Detection and Identification of Sulfur Compounds in Phototrophic Organisms -- Imaging Thiol-Based Redox Processes in Live Cells. Sulfur is one of the most versatile elements in life due to its reactivity in different oxidation and reduction states. In phototrophic organisms, the redox properties of sulfur in proteins, and of sulfur-containing metabolites, are particularly important in the interaction between the reductive assimilation processes of photosynthesis and reactive oxygen species that arise as by-products of electron transport chains. Thiol groups in proteins and metabolites are targets of reactive oxygen species, resulting in potential damage and at the same time giving rise to redox signal cascades that trigger repair reactions and adaptation to environmental stress. Further, reduced sulfur compounds play a prominent role as electron donors for photosynthetic carbon dioxide fixation in anoxygenic phototrophic sulfur bacteria. Interest in the investigation of the multiple functions of sulfur-related processes has increased exponentially in recent years, especially in molecular and cellular biology, biochemistry, agrobiotechnology and ecology. This book provides, for the first time, in-depth and integrated coverage of the functions of sulfur in phototrophic organisms including bacteria, plants and algae; it bridges gaps between biochemistry and cellular biology of sulfur in these organisms, and of biology and environments dominated by them. This book is designed to be a comprehensive resource on sulfur in phototrophic organisms for advanced undergraduate and graduate students, beginning researchers and teachers in the area of photosynthesis, bacterial energy metabolism, biotechnology, plant nutrition, plant production and plant molecular physiology.