Photosynthetic bacteria used to be called blue-green algae, a terrible name since most of them aren’t blue-green and none of them are algae. Most are green, and it is better to call them green bacteria, although some are reddish, yellowish, brownish, blackish or, yes, in some cases bluish-green. ‘Green’ also is sometimes used as a word for photosynthetic, and in that sense, too, green bacteria is a good name. Their scientific name is cyanobacteria.
