natto machine and yogurt machine are similar in principle, and both ferment food by controlling temperature and humidity. Natto machine is mainly used to make natto, while yogurt machine is mainly used to make yogurt. However, their working principle and fermentation process are similar, so they can be used in common. For example, if you want to make yogurt with natto machine, you just need to put the milk and yogurt bacteria in natto machine and set them according to the fermentation time and temperature requirements of yogurt. Similarly, if you want to make natto with a yogurt machine, just put Bacillus natto and soybeans into the yogurt machine and set them according to the fermentation time and temperature requirements of natto. Therefore, natto machine and yogurt machine can be used together.