Bioprocess strategies and recovery processes in gibberellic acid fermentation

Gibberellic acid (GA₃) is a commercially important plant growth hormone, which is gaining much more attention all over the world due to its effective use in agriculture and brewing industry. Industrially it is produced by submerged fermentation technique using Ascomycetous fungusGibberella fujikuroi. Solid state and immobilized cell fermentation techniques had also been developed as an alternative to obtain higher yield of GA₃. This review summarizes the problems of GA₃ fermentation such as production of co-secondary metabolites along with GA₃, substrate inhibition and degradation of GA₃ to biologically inert compound gibberellenic acid, which limits the yield of GA₃ in the fermentation medium. These problems can be overcome by various bioprocessing strategiese.g. two-stage and fed batch cultivation processes. Further research on bioreactor operation strategies such as continuous and/or extractive fermentation with or without cell recycle/retention system need to be investigated for improvement in yield and productivity. Down stream processing for GA₃ isolation is also a challenge and procedures available for the same have been critically evaluated.