Carbon Partitioning in Rubrivivax gelatinosus CBS for Increased Isoprene Production
thesisposted on 01.07.2017, 00:00 by Maxwell I. Keirn
Metabolic engineering can be used to alter or enhance various metabolic pathways in microorganisms for the purpose of producing fuels, chemicals, and pharmaceutical products. In this work, we aim to discover if certain genetic modifications can redirect carbon flux to increase product yields of isoprene, which is used to synthesize rubber. Here, Rubrivivax gelatinosus CBS is used as a bacterial platform for investigating the carbon flux from CO through terpenoid pathways. Methods for increasing feedstock consumption, introduction of foreign genes, and deletion of native genes are all utilized in an attempt to increase isoprene titers. Pathways targeted for deletion are responsible for the production of polyhydroxyalkanoates, which are energy storage molecules. Portions of the mevalonate pathway are added along with an isoprene synthase gene to enable increased production of isoprene. Previous works have shown successful expression of the mevalonate pathway in cyanobacteria, as well as production of isoprene. But no work has been done to investigate redirecting carbon flux from energy storage pathways towards isoprene production. Also, previous works investigating the conversion of CO to isoprene have not used a photosynthetic microorganism to alleviate the energy constraints of growth on CO. We also investigate the transcriptional regulators tied to growth on carbon monoxide, which have not been fully elucidated in CBS.