Final answer:
Miso soup is made with fermented soybean paste, and the fermentation of fish sauce is typically carried out by bacteria from Lactobacillaceae or Bacillaceae. These bacteria break down proteins in fish into amino acids, creating the sauce's unique flavor.
Step-by-step explanation:
The miso soup broth is primarily made out of fermented soybean paste. This fermentation process involves various microorganisms, including bacteria and fungi. In the case of fish sauce, which is also a fermented product, the fermentation process is typically driven by bacteria, particularly those in the family Lactobacillaceae or Bacillaceae. These bacteria are capable of surviving in salty environments and are responsible for breaking down the proteins in fish into amino acids, resulting in the distinctive savory flavor of fish sauce. The bacteria utilize the salt and proteins present in the fish to proliferate and produce the ferments that characterize the sauce.