Boiling does kill most bacteria. That’s the good news. Water at a rolling 212°F (100°C) is like a sauna from hell for germs. Their proteins unravel, and they die within minutes.
But here’s the kicker: heat doesn’t erase toxins. Some bacteria produce nasty poisons that survive a boil. You might kill the bugs, but their “deadly leftovers” stay behind.
That’s why you can’t just reheat old rice and call it a miracle. The toxins from Bacillus cereus can laugh at your boiling water. Yikes.