Study the Relation between Fermentation Characteristics of Submerged Fluid and Improving the Lactic Acid Production by Fungi

Lactic acid (LA) is a colorless, odorless monocarboxylic acid naturally produced by many organisms. This weak acid has extensively used as an excipient in the food, cosmetics, pharmaceutical and chemical industries. The L-isomer is being preferred for food and pharmaceutical applications. Lactic acid can be produced by several microorganisms classified into bacteria, fungi, yeast, cyanobacteria, and algae. Among these microorganisms, lactic acid production using fungal fermentation showed high efficiency. Widely used method for the production of lactic acid is batch fermentation. Hydrodynamic conditions in the fermenter influence the morphology of the fungus and thus the rheology. 

High agitation rates, which are required for optimum mass transfer, lead to high shear stress. Consequently, mycelial networks are fragmented, increasing the amount of free filaments and hence the viscosity. Besides, high viscosity at low agitation rate causes insufficient mass transfer and oxygen limitation. Because of an existing dynamic relationship between fermentation conditions and fungal growth patterns, an improved impeller that was sufficiently flexible for submerged cultures would be an advantage in the design of an efficient enzyme production system.