Development of a Terpenoid-Production Platform in Streptomyces reveromyceticus SN-593

Abstract

Terpenoids represent the largest class of natural products, some of which are resources for pharmaceuticals, fragrances, and fuels. Generally, mass production of valuable terpenoid compounds is hampered by their low production levels in organisms and difficulty of chemical synthesis. Therefore, the development of microbial biosynthetic platforms represents an alternative approach. Although microbial terpenoid-production platforms have been established in Escherichia coli and yeast, an optimal platform has not been developed for Streptomyces species, despite the large capacity to produce secondary metabolites, such as polyketide compounds. To explore this potential, we constructed a terpenoid-biosynthetic platform in Streptomyces reveromyceticus SN-593. This strain is unique in that it harbors the mevalonate gene cluster enabling the production of furaquinocin, which can be controlled by the pathway specific regulator Fur22. We simultaneously expressed the mevalonate gene cluster and subsequent terpenoid-biosynthetic genes under the control of Fur22. To achieve improved fur22 gene expression, we screened promoters from S. reveromyceticus SN-593. Our results showed that the promoter associated with rvr2030 gene enabled production of 212 ± 20 mg/L botryococcene to levels comparable to those previously reported for other microbial hosts. Given that the rvr2030 gene encodes for an enzyme involved in the primary metabolism, these results suggest that optimized expression of terpenoid-biosynthetic genes with primary and secondary metabolism might be as important for high yields of terpenoid compounds as is the absolute expression level of a target gene(s).

Production of Plant-Associated Volatiles by Select Model and Industrially Important Streptomyces spp.

“…As prokaryotes, Streptomyces are relatively easy to manipulate and culture, allowing for the improved and sustainable production of certain chemicals [154]. For example, a terpenoid-production platform was recently developed for Streptomyces reveromyceticus and the titer of botryococcene (a triterpene) was increased by manipulating biosynthetic genes and promoters [155]. It has been reported that VOC biosynthesis is commonly catalyzed by products of single genes rather than gene clusters [16,17,156,157], further simplifying the complexity of gene manipulations required for improving yields.…”

Identifying and engineering the ideal microbial terpenoid production host

“…Our laboratory has recently reported the engineering of methylotrophic yeast P. pastoris for the biosynthesis of the squalene-derived (+)-ambrein, yielding 105 mg L −1 (Moser et al 2018). Other hosts were modified to produce botryococcene in a similar range, such as Streptomyces reveromyceticus SN-593, a strain with a native mevalonate operon, that upon fine-tuning of expression of its global regulator of terpenoid biosynthesis, Fur22, yielded 212 mg L −1 (Khalid et al 2017). Rhodobacter capsulatus produced 110 mg L −1 of botryococcene in an autotrophic cultivation setup supplying only CO 2 , H 2 , and O 2 that yielded almost threefold more in titer compared with a glucose-based fed batch (Khan et al 2015).…”

The Role of Amino Acid Substitution in HepT Toward Menaquinone Isoprenoid Chain Length Definition and Lysocin E Sensitivity in Staphylococcus aureus

“…In addition to MK biosynthesis, isoprenoids are critical for the biosynthesis of membrane lipids, carotenoids, sterols, and other components of the bacterial cell wall (Oldfield, 2010). Isopentenyl-PP, one of the substrates of HepT and the starting molecule for other isoprenoid biosynthesis, is synthesized either via 2-C-methyl-D-erythritol-4-phosphate (MEP) and/or mevalonate pathway (Lange et al, 2000;Khalid et al, 2017). The enzymes of the MEP pathway have been used as targets for antibiotic discovery against microbes that harbor the MEP pathway (Shigi, 1989;Jomaa et al, 1999).…”