Fridge is haven for microbes...

Foods are stored in a fridge to ensure they stay fresh longer. This is possible because the growth of many microorganisms are inhibited at temperature below 7°C. However, that does not stop them from reproducing or forming spores. The lower the temperature, the longer it will take for food to spoil.

Food is an active vehicles; therefore, microorganisms around us linger on the food, especially for pre-prepared/pre-packaged food such as salad, sushi, cold dessert, sashimi and etc. Microorganisms linger on them might find difficulty to survive; however, they can form spore to continue their survivals in the fridge.


Hmm..how actually microbes growth in fridge??
Do you know that, the action of opening and closing the fridge door,  it can raise the fridge temperature by 5°C or more. It needs 2 hours or more to recover back to the adjusted temperature.In addition, most modern freezers are ‘frost free’ ie. The cooling coils in the refrigerator are periodically heated up to prevent frost from forming on them. As such, the defrost cycle can increase the temperature of freezer from -18°C to -10°C.
 
Leftover food might sometimes be stored together with fresh food. This will lead to cross contamination. There is a risk of food poisoning if microorganisms from uncooked food are transferred to cooked food through dripping if it is placed above it. Moreover, Some people put in any food into refrigerator which leads to overstuffing. This affects the cold air circulation of refrigerator which in turn provide warmth for mesophiles to grow inside.


A kind of bacteria know as psychrophiles, they can characterized by lipid cell membranes chemically resistant to the stiffening caused by extreme cold, and often create protein 'antifreezes' to keep liquid and protect their DNA even in temperatures below water's freezing point. their internal space and thus they survive. For more details, please refer to here.

On the other hand, psychrophilic bacteria are adapted to their cool environment by having largely unsaturated fatty acids or polyunsaturated fatty acids in their plasma membranes. Unsaturated fatty acids remain liquid at low thermal transition stage and low temperature. For further information, please visit this link.

Whether fatty acids in a membrane are in a liquid or a solid phase affects the fluidity of the membrane, which directly affects its ability to function. However, psychrophiles have enzymes that continue to function, albeit at a reduced rate, at temperatures at or near 0°C. They have also cold-adapted enzymes to adjust themselves in cold environment.

So, on the whole, please don't think that food storing in the fridge is 100% safe....