Deferentiate between surface and submerged fermentation?

Surface fermentation refers to those fermentations in which the microorganisms utilised grows on the surface of the fermentation media.Examples being citric acid surface fermentation process wherein the microorganism aspergillus Niger grows as a thick floating mycelial mat over the surface of the media used.

Submerged fermentation refers to those fermentations wherein microorganisms employed grows in submerged state within the fermentation media.many fermentations fall in this category like penicillin submerged fermentation technique.