Bioconversion of cis-, trans-cinnamic acids and chlorinated cinnamic acids by resting cell culture of Rhodotorula rubra Y-1529

Fang-Ming Sun, University of Rhode Island

Abstract

This study was conducted to understand the bioconversion pathways of cis-, trans-cinnamic and chlorinated cinnamic acids in R. rubra Y-1529. The cis-isomers produced by photoisomerization of trans-isomers of cinnamic and chlorinated cinnamic acids were fully characterized by GC-mass, FT-IR, and proton NMR. All of the major transformation products from trans-cinnamic acid and chlorocinnamic acids were identified by GC-mass or LC-mass. The bioconversion pathways based on these transformation products are proposed. The inhibition of $\beta$-oxidation by 4-pentenoic acid; and release of ($\sp{14}$C) CO$\sb2$ from U- ($\sp{14}$C) -benzoic acid were used to test this proposed bioconversion pathway. The stereo- and regioselectivity of these bioconversion processes have been established.^ It was found that the first step in the bioconversion of cinnamic and chlorocinnamic acids by R. rubra is the oxidation of the unsaturated C3 side chain to -COOH. This step is specific for trans-isomers and if this step is blocked, no further bioconversion will happen. The results from the 4-pentenoic acid experiments suggest that this stereospecific side oxidation reaction is a $\beta$-oxidation reaction or a reaction related to $\beta$-oxidation. The next step after the side chain oxidation is the hydroxylation of the benzene ring at the para-position. The benzene ring was then cleaved at the 3,4-position to form a ring fission product postulated to be fully oxidized to CO$\sb2$ by the $\beta$-ketoadipate pathway and TCA cycle. This regiospecific ring fission reaction was demonstrated for trans-cinnamic acid and 2chlorocinnamic acid but not for trans-3chloro- and 4chlorocinnamic acids. Resting cell suspensions of R. rubra Y-1529 have been demonstrated to separate a racemic mixture of trans-, cis- cinnamic acids; and trans-, cis-2chlorocinnamic acids on a mg scale. The bioseparation process developed in this study therefore represents a new and valid method for the convenient method of preparation of pure cis-cinnamic and cis-2chlorocinnamic acids. ^

Subject Area

Agriculture, Food Science and Technology|Biology, Microbiology|Environmental Sciences

Recommended Citation

Fang-Ming Sun, "Bioconversion of cis-, trans-cinnamic acids and chlorinated cinnamic acids by resting cell culture of Rhodotorula rubra Y-1529" (1998). Dissertations and Master's Theses (Campus Access). Paper AAI9902579.
http://digitalcommons.uri.edu/dissertations/AAI9902579

Share

COinS