초록
<P><B>Abstract</B></P> <P>The ability of <I>Clostridium butyricum</I> RAK25832 to use casamino acids as a nitrogen source was investigated. Strain RAK25832 showed the capacity to utilize different types of carbon sources. With glucose as a carbon source (10 g/L), the preferred final concentration of casamino acids was 26.67 g/L, with a cumulative hydrogen production, production rate, and yield of 2505 mL H<SUB>2</SUB>/L, 160 mL/h, and 1.81 mol H<SUB>2</SUB>/mol glucose, respectively. Eighteen metal elements were screened to identify the most important metals for biohydrogen production, and four elements were optimized. The optimal medium composition was MgCl<SUB>2</SUB>·6H<SUB>2</SUB>O (0.1 g/L), K<SUB>2</SUB>HPO<SUB>4</SUB>·3H<SUB>2</SUB>O (6.67 g/L), NaHCO<SUB>3</SUB> (2.6 g/L), and FeCl<SUB>2</SUB>·4H<SUB>2</SUB>O (0.002 g/L). Vitamin supplementation of the medium showed no significant effect on hydrogen production. Under the optimized conditions, cumulative hydrogen production reached 3074 mL H<SUB>2</SUB>/L. This is the first study to demonstrate the use of casamino acids as a nitrogen source by <I>C. butyricum</I>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Casamino acid is suitable as a nitrogen source for microbial hydrogen production. </LI> <LI> <I>C. butyricum</I> RAK2583 showed good hydrogen production with various carbon sources. </LI> <LI> The best hydrogen production was obtained with 26.67 g/L casamino acid. </LI> <LI> The fermentation medium for enhanced hydrogen production was optimized. </LI> </UL> </P>