24
P-hydroxystyrene
The phenolic compound p-hydroxystyrene (p-HS) is a valuable intermediate in the
production of polymers, resins, elastomers, and adhesives. The poly(4-hydroxystyrene), for instance, satisfies UV transparency and solubility characteristics for
working as negative photoresist in 248 nm photolithography (Ito 2001; Arie BenBassat et al. 2007). The main way towards p-HS production requires the use of
p-CA as precursor (Fig. 1.8).
To this end the CO 2 -based production of p-CA previously described in Xue et al.
(2014a) and Ni et al. (2016) can be exploited for the further synthesis of p-HS in a
combined process.
Biotransformation of p-HS in whole cells via p-CA decarboxylase activity results
in a low product accumulation since p-HS toxicity (Vogie et al. 2004) precludes its
accumulation in high titers in the fermentation route.
In Arie Ben-Bassat et al. (2007), a concentration of 0.141 M (17 g/L) of p-HS
from p-CA was reached by using the p-hydroxycinnamic acid decarboxylase (PDC)
in a biphasic aqueous toluene solution where the p-HS product is selectively
removed from the aqueous medium. Jung et al. (2013) tested the production of p-HS
from p-CA by engineering the bacterium E. coli with the phenolic acid decarboxylase (PAD) from Bacillus amyloliquefaciens under IPTG-inducible promoter. The
mutant was grown in a biphasic reactor using 1-octanol in phosphate buffer phase
(50 mM, pH 7.0) achieving an accumulation of 0.3 M.
1.4.2 Production of P-Hydroxybenzoate in Engineered
Microorganisms
p-Hydroxybenzoate (p-HBA) is a phenolic benzoate derivative. In the last decades,
p-HBA has acquired increasing relevance as a monomer for the production of liquid
crystal polymers used in cosmetics industry (Vogel and Heitz 1990). Nowadays the
production of large amount of p-HBA comes primarily by the Kolbe–Schmidt reaction where potassium ions react with the anionic charge of the phenolate under high
temperature and pressure (Lindsey and Jeskey 1957). The natural production of
p-HBA in CO 2 -fixing microorganisms occurs in all plants and some cyanobacteria,
albeit usually in small quantities. In Lithospermum erythrorhizon, p-HBA is a precursor of the red naphthoquinone pigment shikonin (Loscher and Heide 1994), while
in Synechocystis p-HBA is the intermediate for the synthesis of the plastoquinone
Fig. 1.8 Decarboxylation of p-coumaric acid (p-CA) to p-hydroxystyrene (p-HS)
A. A. Azim et al.
P-hydroxystyrene
The phenolic compound p-hydroxystyrene (p-HS) is a valuable intermediate in the
production of polymers, resins, elastomers, and adhesives. The poly(4-hydroxystyrene), for instance, satisfies UV transparency and solubility characteristics for
working as negative photoresist in 248 nm photolithography (Ito 2001; Arie BenBassat et al. 2007). The main way towards p-HS production requires the use of
p-CA as precursor (Fig. 1.8).
To this end the CO 2 -based production of p-CA previously described in Xue et al.
(2014a) and Ni et al. (2016) can be exploited for the further synthesis of p-HS in a
combined process.
Biotransformation of p-HS in whole cells via p-CA decarboxylase activity results
in a low product accumulation since p-HS toxicity (Vogie et al. 2004) precludes its
accumulation in high titers in the fermentation route.
In Arie Ben-Bassat et al. (2007), a concentration of 0.141 M (17 g/L) of p-HS
from p-CA was reached by using the p-hydroxycinnamic acid decarboxylase (PDC)
in a biphasic aqueous toluene solution where the p-HS product is selectively
removed from the aqueous medium. Jung et al. (2013) tested the production of p-HS
from p-CA by engineering the bacterium E. coli with the phenolic acid decarboxylase (PAD) from Bacillus amyloliquefaciens under IPTG-inducible promoter. The
mutant was grown in a biphasic reactor using 1-octanol in phosphate buffer phase
(50 mM, pH 7.0) achieving an accumulation of 0.3 M.
1.4.2 Production of P-Hydroxybenzoate in Engineered
Microorganisms
p-Hydroxybenzoate (p-HBA) is a phenolic benzoate derivative. In the last decades,
p-HBA has acquired increasing relevance as a monomer for the production of liquid
crystal polymers used in cosmetics industry (Vogel and Heitz 1990). Nowadays the
production of large amount of p-HBA comes primarily by the Kolbe–Schmidt reaction where potassium ions react with the anionic charge of the phenolate under high
temperature and pressure (Lindsey and Jeskey 1957). The natural production of
p-HBA in CO 2 -fixing microorganisms occurs in all plants and some cyanobacteria,
albeit usually in small quantities. In Lithospermum erythrorhizon, p-HBA is a precursor of the red naphthoquinone pigment shikonin (Loscher and Heide 1994), while
in Synechocystis p-HBA is the intermediate for the synthesis of the plastoquinone
Fig. 1.8 Decarboxylation of p-coumaric acid (p-CA) to p-hydroxystyrene (p-HS)
A. A. Azim et al.