synthase (LS) in Y. lipolytica produced d-limonene with a titre of 23.56 mg/L (Cao
et al. 2016).
Biotransformation of limonene to α-terpineol was performed by Cladosporium
sp. and a yield of 1.0 g/L was obtained (Kraidman et al. 1969). Penicillium digitatum
and Fusarium oxysporum have also been used for this bioconversion (Adams and
Demyttenaere 2003; Maróstica et al. 2007). Extracellular and intracellular
ligninolytic enzymes of white rot fungi, Ceripora sp. ZLY-2010 and Stereum
hirsutum, also carried out the biotransformation of (-)-α-pinene to valuable
terpenoids (Lee et al. 2015).
Biotransformation studies have also been carried for agro-industrial waste
residues from which essential oils have already been extracted. In monoterpenic
agro-industrial wastes such as turpentine oil and essential orange oil, Penicillium
sp. caused biotransformation by submerged liquid culture approach. R-(+)-limonene
and α-, β- pinenes from the oils were biotransformed by Penicillium sp. to produce
α-terpineol and perillyl alcohol, and verbenol and verbenone, respectively
(Maróstica et al. 2007). In the orange peel residues, limonene was biotransformed
into valuable compounds, α-terpineol by Penicillium italicum which was also
isolated from decayed orange peel (Awny et al. 2017).
The biosynthesis of monoterpenes, sesquiterpenes and diterpenes requires
isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMAPP)
as the universal building blocks. There are two pathways to biosynthesize IPP and
DMAPP: the mevalonate (MVA) pathway in eukaryotes such as Saccharomyces
cerevisiae and the 2-methyl-D-erythritol-4-phosphate (MEP) pathway in most bacteria, including Escherichia coli (Carter et al. 2003). Wu et al. (2019) have improved
the production of limonene in E. coli by systematic optimization of the metabolic
flux of limonene biosynthetic pathway. The heterologous limonene biosynthetic
pathway was divided into the upstream, midstream and downstream modules, each
of which was carried out by module genes derived from bacteria (Enterococcus
faecalis), yeast (S. cerevisiae) and plants (Abies grandis and Mentha spicata). The
upstream module from acetyl-CoA to mevalonate was constructed by choosing the
genes EfmvaE and EfmvaS from E. faecalis, which were expressed in the bicistronic
plasmid pMAP1. In the midstream module from mevalonate to IPP and DMAPP, the
genes ScMK, ScPMK, ScPMD and ScIDI from S. cerevisiae were expressed under
the control of T7 promoter as the monocistronic operon in plasmid pISP2. The
downstream module was constructed for the conversion of IPP and DMAPP to
limonene; neryl pyrophosphate synthase (NPPS) from Solanum lycopersicum and
the MsLS from Mentha spicata were separately expressed in the plasmid pGLS,
under two T7 promoters. Three plasmids pMAP1, pISP2 and pGLS were introduced
into strain E. coli BW25113 (DE3) to create strain E. coli ELIM17. Fed-batch
fermentation in a shake-flask was carried for the metabolically engineered strain
ELIM78 and the yield of limonene was reported to be 1.29 g/L in 84 h.
The metabolically engineered gene coding for the enzyme S-linalool synthase
(LIS), responsible for the formation of the monoterpene S-linalool in Clarkia
breweri flowers, was isolated and cloned into a binary vector which was introduced
into A. tumefaciens strain LBA4404. The recombinant bacteria were used to
7 Biotechnological Interventions for Production of Flavour and Fragrance. . .
139
et al. 2016).
Biotransformation of limonene to α-terpineol was performed by Cladosporium
sp. and a yield of 1.0 g/L was obtained (Kraidman et al. 1969). Penicillium digitatum
and Fusarium oxysporum have also been used for this bioconversion (Adams and
Demyttenaere 2003; Maróstica et al. 2007). Extracellular and intracellular
ligninolytic enzymes of white rot fungi, Ceripora sp. ZLY-2010 and Stereum
hirsutum, also carried out the biotransformation of (-)-α-pinene to valuable
terpenoids (Lee et al. 2015).
Biotransformation studies have also been carried for agro-industrial waste
residues from which essential oils have already been extracted. In monoterpenic
agro-industrial wastes such as turpentine oil and essential orange oil, Penicillium
sp. caused biotransformation by submerged liquid culture approach. R-(+)-limonene
and α-, β- pinenes from the oils were biotransformed by Penicillium sp. to produce
α-terpineol and perillyl alcohol, and verbenol and verbenone, respectively
(Maróstica et al. 2007). In the orange peel residues, limonene was biotransformed
into valuable compounds, α-terpineol by Penicillium italicum which was also
isolated from decayed orange peel (Awny et al. 2017).
The biosynthesis of monoterpenes, sesquiterpenes and diterpenes requires
isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMAPP)
as the universal building blocks. There are two pathways to biosynthesize IPP and
DMAPP: the mevalonate (MVA) pathway in eukaryotes such as Saccharomyces
cerevisiae and the 2-methyl-D-erythritol-4-phosphate (MEP) pathway in most bacteria, including Escherichia coli (Carter et al. 2003). Wu et al. (2019) have improved
the production of limonene in E. coli by systematic optimization of the metabolic
flux of limonene biosynthetic pathway. The heterologous limonene biosynthetic
pathway was divided into the upstream, midstream and downstream modules, each
of which was carried out by module genes derived from bacteria (Enterococcus
faecalis), yeast (S. cerevisiae) and plants (Abies grandis and Mentha spicata). The
upstream module from acetyl-CoA to mevalonate was constructed by choosing the
genes EfmvaE and EfmvaS from E. faecalis, which were expressed in the bicistronic
plasmid pMAP1. In the midstream module from mevalonate to IPP and DMAPP, the
genes ScMK, ScPMK, ScPMD and ScIDI from S. cerevisiae were expressed under
the control of T7 promoter as the monocistronic operon in plasmid pISP2. The
downstream module was constructed for the conversion of IPP and DMAPP to
limonene; neryl pyrophosphate synthase (NPPS) from Solanum lycopersicum and
the MsLS from Mentha spicata were separately expressed in the plasmid pGLS,
under two T7 promoters. Three plasmids pMAP1, pISP2 and pGLS were introduced
into strain E. coli BW25113 (DE3) to create strain E. coli ELIM17. Fed-batch
fermentation in a shake-flask was carried for the metabolically engineered strain
ELIM78 and the yield of limonene was reported to be 1.29 g/L in 84 h.
The metabolically engineered gene coding for the enzyme S-linalool synthase
(LIS), responsible for the formation of the monoterpene S-linalool in Clarkia
breweri flowers, was isolated and cloned into a binary vector which was introduced
into A. tumefaciens strain LBA4404. The recombinant bacteria were used to
7 Biotechnological Interventions for Production of Flavour and Fragrance. . .
139