Citrobacter sp. Y19, originally isolated for CO-dependent H 2 production can also ferment glucose over a wide range of temperatures (25–40oC) and pH (5–9) with a maximum H 2 yield of 2.49 mol H 2 .mol–1 glucose and an H 2 production rate of 32.3 mmol H 2 .g–1 cells. h–1 [57].