1. Experimental A seed was cultured in a 120-mL serum bottle (working volume 20 mL) at 37 째C and agitated in a shaking incubator at 220 rpm. After seed cultivation, the inoculum at the late exponential phase (OD680=1.8) was transferred anaerobically into a 500-mL serum bottle (working volume 360 mL). All anaerobic procedures were carried out in an anaerobic chamber (SK-G002-A1, Dwyer Instruments Inc., USA). The serum bottles were sealed with a 12 mm-thick butyl rubber septum and an aluminum cap. For cell growth, cells were cultured at 37 째C in 360 mL of PYG (peptone, yeast extract, and glucose) medium for 6 hr. The PYG medium that was used for cell growth contained 10 g/L glucose, 15 g/L peptone, 3 g/L yeast extract, 0.5 g/L MgSO4