1.
Metab Eng
; 14(5): 528-32, 2012 Sep.
Article
in English
| MEDLINE
| ID: mdl-22781282
ABSTRACT
Genes encoding the enzyme urease were integrated in a Thermoanaerobacterium saccharolyticum ethanologen. The engineered strain hydrolyzed urea, as evidenced by increased cellular growth and elevated final pH in urea minimal medium and urease activity in cell free extracts. Interestingly, replacement of ammonium salts with urea resulted in production of 54 g/L ethanol, one of the highest titers reported for Thermoanaerobacterium. The observed increase in ethanol titer may result from reduced pH, salt, and osmolality stresses during fermentation. Urea utilization is attractive for industrial scale fermentation, where pH control is technically challenging and increased ethanol titer is desirable.
Subject(s)
Bacterial Proteins , Ethanol/metabolism , Gene Expression , Thermoanaerobacterium , Urea/metabolism , Urease , Bacterial Proteins/biosynthesis , Bacterial Proteins/genetics , Clostridium thermocellum/enzymology , Clostridium thermocellum/genetics , Hydrogen-Ion Concentration , Osmotic Pressure , Thermoanaerobacterium/enzymology , Thermoanaerobacterium/genetics , Thermoanaerobacterium/growth & development , Urease/biosynthesis , Urease/genetics
2.
Small
; 6(9): 988-92, 2010 May 07.
Article
in English
| MEDLINE
| ID: mdl-20440703