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Triterpene hydrocarbon production engineered into a metabolically versatile host— Rhodobacter capsulatus
Author(s) -
Khan Nymul E.,
Nybo S. Eric,
Chappell Joe,
Curtis Wayne R.
Publication year - 2015
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.25573
Subject(s) - rhodobacter , triterpene , bioreactor , botryococcus braunii , carbon fixation , chemistry , heterotroph , autotroph , food science , botany , photosynthesis , hydrocarbon , biochemistry , biology , organic chemistry , bacteria , medicine , alternative medicine , genetics , pathology , mutant , gene
Triterpene hydrocarbon biosynthesis of the ancient algae Botryococcus braunii was installed into Rhodobacter capsulatus to explore the production of C 30 hydrocarbon in a host capable of diverse growth habits—utilizing carbohydrate, sunlight or hydrogen (with CO 2 fixation) as alternative energy feedstocks. Engineering an enhanced MEP pathway was also used to augment triterpene accumulation. Despite dramatically different sources of carbon and reducing power, nearly the same level of botryococcene or squalene (∼5 mg oil/g‐dry‐weight [gDW]) was achieved in small‐scale aerobic heterotrophic, anaerobic photoheterotrophic, and aerobic chemoautotrophic growth conditions. A glucose fed‐batch bioreactor reached 40 mg botryococcene/L (∼12 mg/gDW), while autotrophic bioreactor performance with CO 2 , H 2 , and O 2 reached 110 mg/L (16.7 mg/gDW) during batch and 60 mg/L (23 mg/gDW) during continuous operation at a dilution rate corresponding to about 10% of μ max . Batch and continuous autotrophic specific productivity was found to reach 0.5 and 0.32 mg triterpene/g DW/h, comparable to prior reports for terpene production driven by heterotrophic growth conditions. This demonstrates the feasibility of alternative feedstocks and trophic modes to provide comparable routes to biochemicals that do not rely on sugar. Biotechnol. Bioeng. 2015;112: 1523–1532. © 2015 Wiley Periodicals, Inc.