cy·a·no·bac·te·ri·um noun \-bak-ˈtir-ē-əm\
plural cy·a·no·bac·te·ria \-ē-ə\
: any of a major group (Cyanobacteria) of photosynthetic bacteria that produce molecular oxygen and use water as an electron-donating substrate in photosynthesis—called also blue-green alga
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