photobacterial

Etymology tree
Proto-Indo-European *bʰeh₂-
Proto-Indo-European *bʰéh₂os
Proto-Hellenic *pʰáwos
Ancient Greek φᾰ́ος (phắos)
Ancient Greek φῶς (phôs)
Ancient Greek φωτο- (phōto-)der.
English photo-
Ancient Greek βακτηρία (baktēría)
Proto-Indo-European *-yósder.
Ancient Greek -ῐος (-ĭos)?
Ancient Greek -ιον (-ion)
Ancient Greek βακτήριον (baktḗrion)bor.
New Latin bactēriabor.
English bacteria
Proto-Indo-European *h₂el-der.?
Proto-Italic *-ālis
Latin -ālisbor.
Old French -albor.
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Latin -ālis
Old French -elbor.
▲
Latin -ālisbor.
Middle English -al
English -al
English bacterial
English photobacterial
From photo- + bacterial.