Production of lycopene by metabolically engineered Pichia pastoris.

Lycopene is a highly valued carotenoid with wide applications in various industries. The market demand for lycopene promotes research in metabolic engineering of heterologous hosts for lycopene. In this study, Pichia pastoris strain GS115 was genetically engineered to produce lycopene by integrating the heterologous lycopene biosynthesis genes from Corynebacterium glutamicum ATCC13032. The resulting strain, L1, produced 0.115 mg/g cell dry weight (DCW) lycopene. Through optimization by promoter selection, improving the precursor supply and expanding the Geranylgeranyl diphosphate (GGPP) pool, ultimately, the lycopene yield of the final optimal strain was 6.146 mg/g DCW with shake flask fermentation and 9.319 mg/g DCW (0.714 g/L) in a 3 L fermenter. The lycopene yield in this study is the highest yield of lycopene in P. pastoris reported to date, which demonstrated the potential of P. pastoris in lycopene synthesis and as a candidate host organism for the synthesis of other high value-added terpenoids.

Engineering the regulatory site of the catalase promoter for improved heterologous protein production in Pichia pastoris.

OBJECTIVES: To build a stronger Pichia pastoris PCAT1 promoter and to identify putative transcriptional factor binding sites (TFBSs) on PCAT1 that affect the activity of the promoter. RESULT: A synthetic library of PCAT1 was generated by deleting or duplicating putative TFBS motifs in the promoter sequence. CSRE, MIG1, RAP1 and HAP2/3/4 were found to have important effects on PCAT1 activity. The PCAT1 variant P4 with a putative binding site of RAP1 on the promoter sequence showed a stronger activity compared with that of the wild-type PCAT1 and PAOX1, which is the strongest natural P. pastoris promoter that has been reported. This inference was confirmed with EGFP (enhanced green fluorescent protein) and Candida Antarctica lipase B as the reporters. CONCLUSION: The role of the transcriptional regulator RAP1 may be important in PCAT1 methanol induction. A stronger PCAT1 variant can be constructed by the duplication of the putative binding site of RAP1 on the PCAT1 promoter sequence. This PCAT1 variant has potential value for heterologous protein production, metabolic engineering, and synthetic biology.