Differences between solid-state and submerged fermentation:

SOLID STATE FERMENTATION:

1. WATER ACTIVITY = less
2. NATURE OF SUBSTRATE = insoluble (molasses)
3. GROWTH = Solid state microbes adhere at surface and grow on it.
4. SUBSTRATE = Agricultural waste products are usually used (wheat, gram)
5. MEASUREMENT AND CONTROL OF PARAMETERS = pH, aeration, temperature, agitation and foaming are difficult to measure and control.
6. FLUCTATION IN RESULT = Result vary from batch to batch
7. FERMENTATION TYPE = Only batch fermentation
8. FOAMING = Not a major problem.
9. TYPES OF PRODUCTS = Extracellular product
10. PRODUCT YIELD = Higher concentration of products due to larger amount of substrate available.
11. DOWNSTREAM PROCESSING = Difficult and tedious.
12. STEARILIZATION = It may take long time.
13. EXAMPLES = Harvested product compositing, ripening of cheese, mushroom cultivation, enzyme production etc.

SUBMERGED FERMENTATION:

1. WATER ACTIVITY = more (main component)
2. NATURE OF SUBSTRATE = soluble
3. GROWTH = microbes grow in the suspended form of fungi form mat on the surface
4. SUBSTRATE = make use of crude or synthetic substrates. (crude cheese- whey, molasses)(lactose ,starch growth etc)
5. MEASUREMENT AND CONTROL OF PARAMETERS = pH, aeration, temperature, agitation and foaming are easy to measure and control.
6. FLUCTATION IN RESULT = Result do not vary much from batch to batch
7. FERMENTATION TYPE = Run on batch, fed-batch or continuous 
8. FOAMING =  a major problem.
9. TYPES OF PRODUCTS = can be used for both intracellular and Extracellular product
10. PRODUCT YIELD = Yield is low as the product concentration gets diluted due to large volume of medium used.
11. DOWNSTREAM PROCESSING = Easy recovery of the product
12. STEARILIZATION = It is easy to sterilize. Autoclaving may also be used
13. EXAMPLES = Vitamins production, Amino acids, ethanol, enzyme production.