Metagenome analyses of mixed genomes of uncultured microorganisms derived from various environmental samples have been progressively developed, and four million or more of gene candidates are registered in the international DNA databanks without information of their gene functions. As a bioinformatics exercise in Nagahama Institute of Bio-Science and Technology, a database for genes that may contribute achievement of the environmentally sustainable world in a broad sense are constructed. Students independently set and search for, on their own motivation, such genes that may contribute environmental cleanup and detoxification from a huge number of gene candidates obtained by metagenome analyses but left of no use because of lack of annotation concerning their functions. Genes newly annotated by students have been registered in the "Database for Genes Contributing Sustainable World" constructed by our group and publicized with students names. Many gene candidates that are thought to have the potentiality in the heavy metal removal, the degradation of agrichemicals, PCB, or environmental hormones, and the bio-fuel production have been found. The exercise text is available by requests.