Aerobic hydrogen production and dinitrogen fixation in the marine cyanobacterium Trichodesmium erythraeum IMS101

Punshon, Stephen, Robert M. Moore

Limnol. Oceanogr., 53(6), 2008, 2749-2753 | DOI: 10.4319/lo.2008.53.6.2749

ABSTRACT: Rates of hydrogen production and acetylene reduction were measured in aerobic cultures of the marine cyanobacterium Trichodesmium erythraeum IMS101 grown in a supplemented seawater medium low in combined inorganic nitrogen. Both hydrogen production and acetylene reduction conformed to a circadian pattern with maximum activity in the afternoon. Normalized hydrogen production rates ranged from 0.06 to 0.71 nmol H2 µg chlorophyll a (Chl a)-1 h-1, while nitrogen fixation rates, calculated using an assumed ratio of 4 mol acetylene to 1 mol dinitrogen, ranged from 0.12 to 4.71 nmol N2 Chl a-1 h-1. Yields of hydrogen from nitrogen fixation were in the range 0.15-0.48 mol H2 evolved per mol N2 reduced. A comparatively low net rate of H2 uptake was observed in one culture during the dark period (20.01 nmol H2 µg Chl a-1 h-1). These measurements suggest that T. erythraeum is potentially a net source of hydrogen to the low-latitude surface ocean.

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