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Rapid oxygen cycling in Trichodesmium thiebautii
Author(s) -
Kana Todd M.
Publication year - 1993
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1993.38.1.0018
Subject(s) - trichodesmium , dcmu , photosynthesis , oxygen , cyanobacteria , oxygen evolution , chemistry , cycling , nitrogenase , botany , light intensity , photosystem ii , environmental chemistry , nitrogen fixation , nitrogen , biology , diazotroph , bacteria , genetics , organic chemistry , electrode , archaeology , electrochemistry , physics , optics , history
Oxygen uptake and evolution were measured in Trichodesmium thiebautii trichomes with 18 O membrane inlet mass spectrometry. Samples were collected in the vicinity of the Bahamas Islands and eastern Caribbean Sea. Trichodesmium exhibited high rates of oxygen uptake in the dark and in the light compared with previously studied cyanobacteria. Oxygen uptake in the dark averaged 23% of the maximum gross oxygen evolution rate and was suppressed minimally at low irradiances or after the addition of cyanide. Oxygen uptake in light increased between 50 and 200 µ Einst m − 2 s − 1 and was inhibited by 3‐(3,4‐)‐dichlorophenyl)‐1,1‐dimethylurea (DCMU), indicating Mehler reaction activity. I estimate that 48% of the total photosynthetic linear electron flow went to oxygen reduction at moderate but nonsaturating irradiances. Light compensation points ranged from 50 to 300 µ Einst m −2 s −1 with values highest for midday samples. Rapid oxygen cycling may contribute to the protection of nitrogenase by reducing the oxygen tension within the cell or colony during oxygenic photosynthesis and by providing a mechanism (pseudocyclic photophosphorylation) for generating excess ATP for nitrogen fixation.