In Latin maybe. And the phrase you are nitpicking is actually “from a bacteria”. So if you were anything but pedantic, you would exclaim “that requires the ablative of source! In the singular.” Following your logic, the article should read “…from a bacterio”. But wait, Latin has no indefinite article, so whether it is “a bacterium” or “a bacterio”, the noun phrase is redundant since indefiniteness is presupposed in simple noun forms. But “from bacterio” is neither grammatical English nor comprehensible Latin. And the ablative of source usually employs a preposition, so “from a bacteria” should read “ab bacterio” to be exact.