Occurrence of caffeoylquinic acids in bamboo suspension cells cultured under light

Rational metabolic-flow switching is an effective strategy that we previously proposed to produce exogenous high-value natural products in cultured plant cells through redirecting a highly active inherent metabolic pathway to a pathway producing related exogenous compounds. In previous proof-of-concept studies, we demonstrated that bamboo (Phyllostachys nigra; Pn) cells are a suitable host for production of phenylpropanoid-derived compounds, in particular those derived from feruloyl- and p-coumaroyl-CoAs. To expand the utility of Pn cells for production of exogenous metabolites via the rational metabolic-flow switching strategy, it is important to evaluate the metabolic potential of Pn cells under diverse culture conditions. In this study, we examined highly active metabolic pathway(s) in Pn suspension cells cultured under light. The Pn suspension cells strongly accumulated two light-induced compounds. These compounds were isolated and identified as 3-O-caffeoylquinic acid (neochlorogenic acid) and its regioisomer 5-O-caffeoylquinic acid (chlorogenic acid). Through optimization of the culture conditions, production titers of 3-O-caffeoylquinic acid and 5-O-caffeoylquinic acid in the Pn suspension cells reached 121 and 77.9 mg l^-1, respectively. These findings indicate that Pn cells are a suitable host for bioproduction of exogenous metabolites, in particular those derived from caffeoyl-CoA via the rational metabolic-flow switching strategy.