The main culprits are microbial organisms known as specific spoilage organisms (SSOs). The concept of SSOs arises from the fact that not all bacteria cause food spoilage; indeed, the degree of food spoilage is not proportional to the amount of microbes present on the food.n general, without further preservation techniques, the environment of a fresh fish provides an abundance of biosynthetic materials that the spoilage organisms such as Shewanella putrefaciens and Pseudomonas spp. can readily use to survive and proliferate.