Effect of C/N Ratio on Enzymatic Activity for Microbial Lipid Production

The main factor affecting lipid accumulation by microorganisms is a high C/N-ratio and the concentration of the trace elements K⁺, Ca²⁺, Zn²⁺, Fe³⁺ and Mn²⁺. While deficiencies in such nutrients as nitrogen, sulfur, phosphorus, and iron have been reported as being able to cause cell growth cessation and channeling of metabolic flux to lipid/fatty acid biosynthesis, the most commonly used limiting-nutrient is nitrogen as it is easily controllable through media composition. Although this fact has been well documented, most of the reports deal with the effect of initial C/N-ratio on the ultimate lipid accumulation by cells in batch cultures. This work deals with the effect of C/N-ratio and specific growth rate of cells on the activities of key enzymes of lipid pathway and on lipid accumulation under steady state conditions.