Aerobic nitrogenase activity measured as acetylene reduction in the marine non-heterocystous cyanobacteriumTrichodesmiumspp. grown under artificial conditions
✍ Scribed by K. Ohki; Y. Fujita
- Book ID
- 104753178
- Publisher
- Springer-Verlag
- Year
- 1988
- Tongue
- English
- Weight
- 452 KB
- Volume
- 98
- Category
- Article
- ISSN
- 0025-3162
No coin nor oath required. For personal study only.
✦ Synopsis
Aerobic nitrogenase activity in the marine non-heterocystous cyanobacterium Trichodesmium spp. NIBB 1067, isolated off the Izu Peninsula, Japan in 1983 and grown under artificial conditions, was assayed by the acetylene reduction method. This strain exhibited acetylene reduction activity under aerobic conditions when cells had been grown in the medium free of combined nitrogen. Activity was markedly enhanced by light, and dependent on the growth phase being higher during the exponential growth phase and lower during the late linear and stationary growth phases. Since typical colony formation occurred during the last growth phase, the present results contradict the idea that N2-fixation depends on colony formation. The photosynthesis inhibitor DCMU at 10 -6 M inhibited lightdependent acetylene reduction completely. Acetylene reduction by Trichodesmium spp. was tolerant of 02 as strongly as that in the heterocystous cyanobacteria. Even at a partial pressure of oxygen (Po2) of ~3 atm, the activity still remained as high as half of the maximum. It was almost under anaerobic conditions. Maximum activity was obtained at pO2 of ca. 0.1 atm.