If it is dipped in boiling water of 100°C for a few minutes, most of the sundry germs will boil and die, but the spores of bacillus subtilis natto will survive.
100°Cで沸騰している湯に数分浸すと大部分の雑菌が煮沸されて死滅し、納豆菌芽胞が生き残る。