I accidentally swallowed a drop from a packet of "beneficial" bacteria turtle water conditioner when i was changing my turtles water.what could happen?

Nobody really knows: What’s good for the goose is good for the gander, but what's good for the turtle... well, who knows? Beneficial bacteria in aquarium water conditioners are to alter the chemical balance, to be better for fish or turtles. That is different that having beneficial probiotics in our yogurt. Most likely, nothing will happen because we can neutralize or digest germs (like accidentally swallowing a bug).