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#metabolite production

2 public questions tagged with this topic.

Plant tissue culture 1

Increase in secondary metabolites in cell culture is commonly achieved by:

Increasing secondary metabolite accumulation in plant cell cultures is commonly achieved by supplementation with elicitors after achieving adequate biomass. Secondary metabolism is resource costly competing with primary growth for carbon nitrogen and energy, regulated by growth defense trade off controlled by TOR kinase promoting growth versus SnRK1 promoting defense. Under normal culture high auxin low stress conditions flux stays in primary metabolism. Elicitor addition artificially activates jasmonate and salicylate mediated defense transcriptome inducing genes encoding rate limiting enzymes: phenylalanine ammonia lyase PAL for flavonoids rosmarinic acid, tryptophan decarboxylase for alkaloids, HMGR for terpenoids, and transcription factors ORCA3 in Catharanthus roseus regulating strictosidine synthase. Timing matters addition at late log phase prevents growth inhibition while maximizing product up to 10-20 fold. Combining elicitation with precursor feeding, media optimization reduced nitrogen, and permeabilizing agents DMSO enhances release. Industrial examples include methyl jasmonate raising paclitaxel in Taxus cell cultures, yeast extract raising shikonin in Lithospermum, chitosan raising berberine in Coptis, forming basis of biotechnological production of pharmaceuticals pigments and flavors in bioreactors.

Ref: Mishra & Ranjan 2008 secondary metabolite; PubMed elicitor methyl jasmonate.

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Plant tissue culture 1

Elicitors enhance secondary metabolite production by:

Elicitors boost secondary metabolite production by mimicking biotic attack triggering plant innate defense signaling and activation of defence related enzymes. Biotic elicitors include fungal cell wall fragments chitin chitosan glucans yeast extract bacterial flagellin; abiotic include jasmonic acid methyl jasmonate salicylic acid heavy metals copper cadmium UV-C ozone. Perception by pattern recognition receptors triggers calcium influx cyclic nucleotide gated channels, production of reactive oxygen species via NADPH oxidase RBOH, activation of mitogen activated protein kinase cascades MPK3 MPK6 leading to jasmonate isoleucine synthesis. Jasmonate signals transcription factors MYB WRKY ORCA that bind promoters of phenylpropanoid pathway enzyme phenylalanine ammonia lyase PAL cinnamate 4 hydroxylase chalcone synthase CHS, and terpenoid pathway HMGR terpene synthase. Resulting phytoalexins alkaloids paclitaxel vincristine flavonoids accumulate up to tenfold. Commercial process employs two stage culture: biomass accumulation stage low elicitor high auxin, then production stage elicitor addition at late exponential phase to redirect carbon flux from primary to secondary metabolism without severe growth inhibition enabling industrial bioreactor harvesting.

Ref: Ramachandra & Ravishankar Plant Cell Rep 2002 elicitors; Nature Plants secondary metabolism.

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