Heterologous expression of C30 carotenoid biosynthetic gene crtNM from Lactiplantibacillus plantarum

BACKGROUND Probiotic lactic acid bacterium Lactiplantibacillus plantarum is widely used in the dairy and other fermented food industries. L. plantarum AR113 harbors a C-30 carotenoid operon crtNM based on genomic analysis, but the yield of C-30 carotenoid is only 8.1 mu g g(-1) DCW. RESULTS To improve the productivity of C-30 carotenoid, crtNM from L. plantarum AR113 was cloned and reconstructed in Escherichia coli BL21(DE3). The proteins crtN and crtM were successfully expressed based on a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, and the carotenoid was detected using high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). In comparison with the constitutive promoter P-44, the use of the inducible T7 promoter significantly increased the carotenoid content in E. coli. The fermentation conditions were also optimized with induction by 0.5 mmol/L IPTG at 20 degrees C for 7 h. The yield of C-30 carotenoid reached 154.5 mu g g(-1) DCW, which was 18-fold higher than that of L. plantarum AR113. The 2,2-diphenyl-1-picryl (DPPH) and 2,2 '-azino-bis (3-ethylbenzothiazoline-6sulfonic acid (ABTS) radical scavenging capacity of C-30 carotenoids synthesized by heterologous expression in E. coli was also higher than that of the antioxidant food additive butylated hydroxytoluene. CONCLUSIONS Our findings suggest that E. coli has strong potential as a basic chassis for the production of C-30 carotenoids from Lactiplantibacillus with high antioxidant activity. (c) 2022 Society of Chemical Industry.