Morphological Changes in Submerged Cultivation of Aspergillus awamori for Glucoamylase Production

Industrial processes involving submerged fermentation of fungal cultures require greater attention due to complex morphologies. Growth of Aspergillus awamori was investigated in submerged culture using different parameters such as pH and agitator speed with a goal to assess the morphology and fragmentation behaviour during the fermentation. Microscopic examination of the mycelia revealed that the length of the branches decreased with increasing pH. Pellet formation was significant at pH 5.5 and the diameter of the pellet was found to vary with fermentation time. A maximum pellet diameter of 1.69 mm was observed at a pH of 7.5, which decreased to 0.38 mm for cultivations at pH of 3.5. During mechanical agitation, fragmentation was found to dominate fungal growth and branching. Agitator speeds higher than 600 rpm resulted in decreased cell growth and glucoamylase production.