Dark Hydrogen Evolution and Adenine Nucleotides of Subtropical Marine Unicellular Green Algae during Anaerobic Incubation

The relation between dark anaerobic hydrogen (H₂) evolutionof marine unicellular green algae and the energetic state ofthe cells, as revealed by adenine nucleotide (AN) levels, wasstudied. One of the 4 investigated strains produced H₂ continuouslyfor 48 h and maintained its adenylate energy charge (EC) atabout 0.6, whereas the H₂ evolution of the other strains stoppedwithin 24 h and their EC decreased to low values. Prolongedaerobic preincubation resulted in reduced H₂ evolution and astronger decrease in EC during subsequent anaerobiosis. Amongcultures of the same strain, H₂ evolution was correlated withthe initial pool levels of total AN and chlorophyll and withthe ATP level and EC during anaerobiosis. These results indicatea dependence between H₂ evolution and capacity for starvation.EC was not affected by complete inhibition of H₂ evolution bycarbon monoxide in one strain but was significantly loweredin another strain. This difference between the two strains isinterpreted as reflecting a different dependence on, or utilizationof, alternative pathways for disposal of electrons during fermentation,although H₂ evolution apparently played a minor and non-essentialrole in the dark anaerobic fermentation. ¹ Present address: Institute of Oceanic Research and Development,Tokai University, Orido, Shimizu, Shizuoka 424, Japan. ² Present address: Institute of Marine Research, Directorateof Fisheries, P.O. Box 1870, N-5011 Bergen-Nordnes, Norway. (Received November 19, 1986; Accepted March 17, 1987)