Other major metabolic end products are acetate and ethanol. Another bacterium, Rhodopseudomonas palustris P4, isolated by the same group for its CO-dependent H 2 production abilities was also studied for its capacity for fermentative H 2 production in batch mode. Maximum H 2 yields were 2.76 mol H 2 . mol–1 glucose and H 2 product-ion rates were 29.9 mmol H 2 . g–1 cell. h–1 with ethanol, acetate and CO 2 as the other major metabolites.