Figure 3

Nitrogen cycling of the sponge symbionts.

GDH: glutamate dehydrogenase (1,698 reads); amo: ammonia monooxygenase (25,374 reads); nar: nitrate reductase (8,461 reads); glt: glutamate synthase (4,401 reads); nor: nitric oxide reductase (736 reads); napA: periplasmic dissimilatory nitrate reductase (243 reads); nirK: Copper-containing nitrite reductase (151 reads); nosZ: nitrous oxide reductase (110 reads); nif: nitrogenase (146 reads); nrfA: cytochrome c nitrite reductase (7 reads). The question mark means the functional gene is not detected in the metagenome.