Physiological roles of pyruvate ferredoxin oxidoreductase and pyruvate formate-lyase in Thermoanaerobacterium saccharolyticum JW/SL-YS485. Issue 1 (December 2015)

• Record Type: Journal Article
• Authors: Zhou, Jilai; Olson, Daniel; Lanahan, Anthony; Tian, Liang; Murphy, Sean; Lo, Jonathan; Lynd, Lee
• Is Part Of: Biotechnology for biofuels. Volume 8:Issue 1(2015)
• Page Start: 1
• Page End: 14
• Publication Date: 2015-12
• Subjects: Thermoanaerobacter saccharolyticum -- Pyruvate metabolism -- Pyruvate ferredoxin oxidoreductase -- Pyruvate formate-lyase -- C1 metabolism; Biotechnology -- Periodicals; Biomass energy -- Periodicals; Energy-Generating Resources -- Periodicals; 662.88
• DOI: 10.1186/s13068-015-0304-1
• Languages: English
• ISSNs: 1754-6834

Abstract

Abstract Background Thermoanaerobacter saccharolyticum is a thermophilic microorganism that has been engineered to produce ethanol at high titer (30–70 g/L) and greater than 90 % theoretical yield. However, few genes involved in pyruvate to ethanol production pathway have been unambiguously identified. InT. saccharolyticum, the products of six putativepfor gene clusters and onepfl gene may be responsible for the conversion of pyruvate to acetyl-CoA. To gain insights into the physiological roles of PFOR and PFL, we studied the effect of deletions of several genes thought to encode these activities. Results It was found that pyruvate ferredoxin oxidoreductase enzyme (PFOR) is encoded by thepforA gene and plays a key role in pyruvate dissimilation. We further demonstrated that pyruvate formate-lyase activity (PFL) is encoded by thepfl gene. Although thepfl gene is normally expressed at low levels, it is crucial for biosynthesis inT. saccharolyticum . InpforA deletion strains, pfl expression increased and was able to partially compensate for the loss of PFOR activity. Deletion of bothpforA andpfl resulted in a strain that required acetate and formate for growth and produced lactate as the primary fermentation product, achieving 88 % theoretical lactate yield. Conclusion PFOR encoded by Tsac_0046 and PFL encoded by Tsac_0628 are only two routes for converting pyruvate to acetyl-CoA inT. saccharolyticum . The physiological role of PFOR is pyruvate dissimilation, whereas that of PFL is supplying C1 units for biosynthesis.