Improved Production and In Situ Recovery of Sesquiterpene (+)-Zizaene from Metabolically-Engineered <i>E. coli</i>

The sesquiterpene (+)-zizaene is the direct precursor of khusimol, the main fragrant compound of the vetiver essential oil from <i>Chrysopogon zizanioides</i> and used in nearly 20% of men&#8217;s fine perfumery. The biotechnological production of such fragrant sesquiterpenes is a pr...

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Bibliographic Details
Main Authors: Francisco Aguilar, Thomas Scheper, Sascha Beutel
Format: Article
Language:English
Published: MDPI AG 2019-09-01
Series:Molecules
Subjects:
Online Access:https://www.mdpi.com/1420-3049/24/18/3356
Description
Summary:The sesquiterpene (+)-zizaene is the direct precursor of khusimol, the main fragrant compound of the vetiver essential oil from <i>Chrysopogon zizanioides</i> and used in nearly 20% of men&#8217;s fine perfumery. The biotechnological production of such fragrant sesquiterpenes is a promising alternative towards sustainability; nevertheless, product recovery from fermentation is one of the main constraints. In an effort to improve the (+)-zizaene recovery from a metabolically-engineered <i>Escherichia coli</i>, we developed an integrated bioprocess by coupling fermentation and (+)-zizaene recovery using adsorber extractants. Initially, (+)-zizaene volatilization was confirmed from cultivations with no extractants but application of liquid&#8722;liquid phase partitioning cultivation (LLPPC) improved (+)-zizaene recovery nearly 4-fold. Furthermore, solid&#8722;liquid phase partitioning cultivation (SLPPC) was evaluated by screening polymeric adsorbers, where Diaion HP20 reached the highest recovery. Bioprocess was scaled up to 2 L bioreactors and in situ recovery configurations integrated to fermentation were evaluated. External recovery configuration was performed with an expanded bed adsorption column and improved (+)-zizaene titers 2.5-fold higher than LLPPC. Moreover, internal recovery configuration (IRC) further enhanced the (+)-zizaene titers 2.2-fold, whereas adsorption velocity was determined as critical parameter for recovery efficiency. Consequently, IRC improved the (+)-zizaene titer 8.4-fold and productivity 3-fold from our last report, achieving a (+)-zizaene titer of 211.13 mg L<sup>&#8722;1</sup> and productivity of 3.2 mg L<sup>&#8722;1</sup> h<sup>&#8722;1</sup>. This study provides further knowledge for integration of terpene bioprocesses by in situ product recovery, which could be applied for many terpene studies towards the industrialization of fragrant molecules.
ISSN:1420-3049