Hello; this sounds correct. From way back in my microbiology days I seem to recall that it is not the bacteria them selves that kill but it is the metabolic waste byproducts (toxins) the bacteria excrete. Eat enough of the toxins and you are poisonedA sample of uneaten pasta was examined and results revealed the presence of Bacillus cereus.
I guess it is silmlar in some manner to the nitrites we can get in out tanks from the first type of beneficial bacteria (bb). The bb that take in ammonia and excrete nitrites as a waste product.