Toward a photosynthetic microbial platform for terpenoid engineering

Abstract

Plant terpenoids are among the most diverse group of naturally-occurring organic compounds known, and several are used in contemporary consumer products. Terpene synthase enzymes catalyze complex rearrangements of carbon skeleton precursors to yield thousands of unique chemical structures that range in size from the simplest five carbon isoprene unit to the long polymers of rubber. Such chemical diversity has established plant terpenoids as valuable commodity chemicals with applications in the pharmaceutical, neutraceutical, cosmetic, and food industries. More recently, terpenoids have received attention as a renewable alternative to petroleum-derived fuels and as the building blocks of synthetic biopolymers. However, the current plant- and petrochemical-based supplies of commodity terpenoids have major limitations. Photosynthetic microorganisms provide an opportunity to generate terpenoids in a renewable manner, employing a single consolidated host organism that is able to use solar energy, H2O and CO2 as the primary inputs for terpenoid biosynthesis. Advances in synthetic biology have seen important breakthroughs in microbial terpenoid engineering, traditionally via fermentative pathways in yeast and Escherichia coli. This review draws on the knowledge obtained from heterotrophic microbial engineering to propose strategies for the development of microbial photosynthetic platforms for industrial terpenoid production. The importance of utilizing the wealth of genetic information provided by nature to unravel the regulatory mechanisms of terpenoid biosynthesis is highlighted.

Engineering Limonene and Bisabolene Production in Wild Type and a Glycogen-Deficient Mutant of Synechococcus sp. PCC 7002

“…In the context of photoautotrophic biotechnology, the terpenoid biosynthetic pathway is of particular interest, as it produces the largest and most diverse array of naturally occurring organic compounds (typically of plant origin) (Davies et al, 2014). The plant terpenoids limonene (C 10 H 16 ) and bisabolene (C 15 H 24 ) are recognized as precursors to a range of commercially valuable products, with applications in biofuels, bioplastics, pharmaceutical, nutraceutical, and cosmetic industries (Duetz et al, 2003; Peralta-Yahya et al, 2011).…”

Identification of novel isoprene synthases through genome mining and expression in Escherichia coli

“…Isoprene, i.e. 2-methyl-1,3-butadiene, and other isoprenoids have been used in the pharmaceutical, nutraceutical, flavour, fragrance, and rubber industries (Ajikumar et al, 2010;Davies et al, 2014;Lemuth et al, 2011;Zhan et al, 2014). The industrial supply of isoprene is limited to petrochemical-based sources.…”

“…Until now, commercially viable quantities of isoprene have been obtained by direct isolation from petroleum C5 cracking fractions or by dehydration of C5 isoalkanes or isoalkenes. However, the increasing global demand for isoprene ϯ calls for novel sources of isoprene (Bentley and Melis, 2012;Davies et al, 2014;Lv et al, 2014;Miller et al, 2001;Xue and Ahring, 2011;Zhao et al, 2011), and the industry has a strong interest in finding a commercially viable and environmentally sustainable production process (Choi et al, 2015;Whited et al, 2010). Therefore, the development of microbial isoprene production is gaining increased interest.…”

An exception among diatoms: unique organization of genes involved in isoprenoid biosynthesis in Rhizosolenia setigera CCMP 1694

“…Davies et al . () further highlighted the occurrence of similar gene structures of IDI fused to SQS in other genome‐sequenced diatoms and other heterokonts, as well as in haptophytes. Our efforts have been focused on elucidating the underlying mechanisms that could contribute to HBI formation in R .…”