Abstract
Lycopene is an import ant compound with an increasing industrial value. However, there is still no biotechnological process to obtain it. In this study, a semi-continuous system for lycopene extraction from recombinant Escherichia coli BL21 cells is proposed. A two-phase culture mode using organic solvents was found to maximize lycopene production through in situ extraction from cells. Within the reactor, three phases were formed during the process: an aqueous phase containing the recombinant E. coli, an interphase, and an organic phase. Lycopene was extracted from the cells to both the interphase and the organic phase and, consequently, thus enhancing its production. Maximum lycopene production (74.71 ± 3.74 mg L−1) was obtained for an octane-aqueous culture system using the E. coli BL21LF strain, a process that doubled the level obtained in the control aqueous culture. Study of the interphase by transmission electron microscopy (TEM) showed the proteo-lipidic nature and the high storage capacity of lycopene. Moreover, a cell viability test by flow cytometry (CF) after 24 h of culture indicated that 24 % of the population could be re-used. Therefore, a batch series reactor was designed for semi-continuous lycopene extraction. After five cycles of operation (120 h), lycopene production was similar to that obtained in the control aqueous medium. A final specific lycopene yield of up to 49.70 ± 2.48 mg g−1 was reached at 24 h, which represents to the highest titer to date. In conclusion, the aqueous-organic semi-continuous culture system proposed is the first designed for lycopene extraction, representing an important breakthrough in the development of a competitive biotechnological process for lycopene production and extraction.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-015-0150-3) contains supplementary material, which is available to authorized users.
Highlights
Lycopene is a tetraterpenoid (C40) precursor of carotenoids
We propose the first semi-continuous system to produce and extract high amounts of lycopene employing a recombinant E. coli strain
All cultures were made by orbital shaking at 200 rpm and 28 °C, which is the optimal temperature for lycopene biosynthesis (Kim et al 2011)
Summary
Lycopene is a tetraterpenoid (C40) precursor of carotenoids. Traditionally, it was considered a colorant and a food additive, but new applications have been proposed for use as an antioxidant (Chasse et al 2001) and anticarcinogen (Giovannucci et al 2002; Rabi and Gupta 2008) and for preventing against cardiovascular diseases (Rao 2002), hepatic fibro-genesis (Kitade et al 2002) or humanIn industry, methods based on metabolic engineering are the most profitable due to their high productivity and, the search for a biotechnological method for lycopene production is an important challenge for many researchers. Lycopene is a tetraterpenoid (C40) precursor of carotenoids. Many studies have been reported concerning lycopene production by metabolic engineering, some of which are based on E. coli, the most important cell factory microorganism in biotechnology (Kim and Keasling 2001; Martin et al 2003; Alper et al 2006; Yuan et al 2006; Gallego‐Jara et al AMB Expr (2015) 5:65. Previous works demonstrated that carotenoid production can be improved by increasing the amount of IPP and its isomer dimethylallyl pyrophosphate (DMAPP) amount available in the recombinant E. coli engineered (Jin and Stephanopoulos 2007; Zhou et al 2012; Zhang et al 2013). Besides to E. coli, carotenogenic microorganisms, such as Blakeslea trispona (Xu et al 2007) and the non-carotenogenic yeasts, Pichia pastoris (Araya-Garay et al 2012) and Saccharomyces cerevesiae (Bahieldin et al 2014), have been used to produce lycopene
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