Reaction catalyzed by hydrogen dehydrogenase (1.12.1.2), hydrogen dehydrogenase (NADP+) (1.12.1.3), ferredoxin hydrogenase (1.12.7.2), hydrogenase (acceptor) (1.12.99.6)

		+			=			+
	H2	+		oxidized methylene blue	=		H+	+		reduced methylene blue