Yes, BACTERIAS is a Scrabble word!

Letter values in Scrabble US: B 3, A 1, C 3, T 1, E 1, R 1, I 1, A 1, S 1.

Is it a valid word?

BACTERIAS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(microbiology) single-celled or noncellular spherical or spiral or rod-shaped organisms lacking chlorophyll that reproduce by fission; important as pathogens and for biochemical properties; taxonomy is difficult; often considered to be plants