Enhanced production of vanillin flavour metabolites by precursor feeding in cell suspension cultures of Decalepis hamiltonii Wight & Arn., in shake flask culture

The flavour rich tuberous roots of Decalepis hamiltonii are known for its edible and medicinal use and have become endangered due to commercial over-exploitation. Besides 2-Hydroxy-4-methoxy benzaldehyde (2H4MB), other flavour metabolites in tuberous roots include vanillin, 4-Methoxy Cinnamic acid derivatives, aromatic alcohols etc. So far, there are no reports on the pathway of 2H4MB biosynthesis nor there is an organized work on biotransformation using normal and cell suspension cultures for obtaining these metabolites using precursors. The main aim of the study is to develop a method for enhanced production of flavour attributing metabolites through ferulic acid (FA) feeding to the D. hamiltonii callus culture medium. Biomass of D. hamiltonii cell suspension cultures was maximum (200.38 +/- 1.56 g/l) by 4th week. Maximum production of 2H4MB was recorded on 4th week (0.08 +/- 0.01 mg/100 g dry weight) as quantified by HPLC. Addition of 0.1-1.5 mM ferulic acid as precursor in the culture medium showed significant (p < 0.001) effect on suspension cultures biomass and respective phenylpropanoid metabolites content and 2H4MB accumulation. The maximum accumulation of vanillin, 2H4MB, vanillic acid, ferulic acid were of 0.1 +/- 0.02 mg/100 g, 0.44 +/- 0.01 mg/100 g, 0.52 +/- 0.04 mg/100 g, 0.18 +/- 0.02 mg/100 g DW respectively in 4 weeks of cultured cells supplemented with 1 mM ferulic acid as a precursor. The results indicate that, substantial increase in the levels of flavour metabolites in D. hamiltonii callus suspension culture was achieved. This would be having implications in biosynthesis of respective vanilla flavour attributing metabolites at very high levels for their large scale production.