Methyl Jasmonate and Methyl-β-Cyclodextrin Individually Boost Triterpenoid Biosynthesis in Chlamydomonas Reinhardtii UVM4.

Audrey S Commault,Raffaela M Abbriano,Mathieu Pernice,Andrei Herdean,Ana Cristina Jaramillo-Madrid,Michele Fabris,Peter J Ralph,Unnikrishnan Kuzhiumparambil

doi:10.3390/ph14020125

Abstract

The commercialisation of valuable plant triterpenoids faces major challenges, including low abundance in natural hosts and costly downstream purification procedures. Endeavours to produce these compounds at industrial scale using microbial systems are gaining attention. Here, we report on a strategy to enrich the biomass of the biotechnologically-relevant Chlamydomonas reinhardtii strain UVM4 with valuable triterpenes, such as squalene and (S)-2,3-epoxysqualene. C. reinhardtii UVM4 was subjected to the elicitor compounds methyl jasmonate (MeJA) and methyl-β-cyclodextrine (MβCD) to increase triterpene yields. MeJA treatment triggered oxidative stress, arrested growth, and altered the photosynthetic activity of the cells, while increasing squalene, (S)-2,3-epoxysqualene, and cycloartenol contents. Applying MβCD to cultures of C. reinhardtii lead to the sequestration of the two main sterols (ergosterol and 7-dehydroporiferasterol) into the growth medium and the intracellular accumulation of the intermediate cycloartenol, without compromising cell growth. When MβCD was applied in combination with MeJA, it counteracted the negative effects of MeJA on cell growth and physiology, but no synergistic effect on triterpene yield was observed. Together, our findings provide strategies for the triterpene enrichment of microalgal biomass and medium.

Highlights

With more than 20,000 different molecules reported to date, triterpenes are one of the widest classes of natural products, of which the highest diversity is found in the plant kingdom [1,2]
We recently demonstrated that C. reinhardtii cells responded to methyl jasmonate (MeJA) treatment (1 mM) by up-regulating the methyl-D-erythritol 4-phosphate (MEP) pathway leading to the accumulation of the triterpenoids precursors FPP, squalene and (S)-2,3-epoxysqualene
The current study investigated the response of strain UVM4 to two elicitors MeJA and methyl-β-cyclodextrin (MβCD) as production strategies to enrich the microalgal biomass with triterpenoid precursors such as squalene and (S)-2,3-epoxysqualene, and to accumulate sterols in the growth medium, thereby simplifying the extraction procedure

Summary

Introduction

With more than 20,000 different molecules reported to date, triterpenes are one of the widest classes of natural products, of which the highest diversity is found in the plant kingdom [1,2]. Triterpenoids comprise structurally diverse compounds that are involved in primary or secondary metabolism. The only triterpenes that belong to the primary metabolism [3], are key structural components of cell membranes, and act as signalling molecules (steroidal hormones). Several triterpenes have a large range of industrial applications in the food and cosmetics sectors, as well as significant potential with pharmaceuticals [2,4]. Phytosterols are used to lower blood LDL cholesterol [5], ergosterol is used for the synthesis of vitamin D2 (ergocalciferol) [6], and the plant triterpene betulinic acid has shown promise for the treatment of HIV and certain cancers in animal models [7,8]

Methods

Results

Discussion

Conclusion