People
Prof Donald BRYANT
Visiting Professor
Pennsylvania State University, USA
Email: dab14@psu.edu

Professor Bryant is a microbial ecophysiologist who has applied cutting-edge genomics, genetics, biochemistry, chemistry, and structural biology to study chlorophototrophic bacteria—Cyanobacteria, Chloroflexi, Chlorobi, and Acidobacteria—for forty years. His early studies focused on structural and functional analyses of phycobilisomes, the light-harvesting complexes of cyanobacteria. Subsequent studies focused on structural and functional studies of Photosystem I, including applications for biofuels production. His elucidation of chlorophyll and carotenoid biosynthetic pathways enabled structural and functional studies of chlorosomes, the light-harvesting antennae of green bacteria. He studied phototrophic microbial mats in Yellowstone hot springs, where members of four taxa are present and high temperatures (>60°C) exclude eukaryotes. Using systems biology approaches, Prof. Bryant and collaborators have made significant progress in advancing our understanding of the interdependence and integration of members of this community. His discovery of “Candidatus Chloracidobacterium thermophilum” [Science (2007) 317, 523-526] and characterisation of the first chlorophototrophic member of the phylum Acidobacteria, are featured in the current edition of Brock Biology of Microorganisms. This novel photoheterotroph has recently been rendered axenic and can now be grown in a completely defined medium. He also recently demonstrated that cyanobacteria have a complete tricarboxylic acid cycle (TCA), overturning the conventional knowledge of nearly fifty years that the cyanobacterial TCA cycle is interrupted due to the absence of 2-oxoglutarate dehydrogenase. Zhang and Bryant convincingly established an alternative biochemical solution to the absence of this enzyme that allows conventional functioning of the TCA cycle in cyanobacteria [Science (2011) 334, 1551-1553].