Received 10 July 1989. Accepted 21 August 1989.
BACTERIAL ASSOCIATIONS WITH MARINE OSCILLATORIA SP. (TRICHODESMIUM SP.) POPULATIONS: ECOPHYSIOLOGICAL IMPLICATIONS1
Version of Record online: 29 OCT 2004
Journal of Phycology
Volume 25, Issue 4, pages 773–784, December 1989
How to Cite
Paerly, H. W., Bebout, B. M. and Prufert, L. E. (1989), BACTERIAL ASSOCIATIONS WITH MARINE OSCILLATORIA SP. (TRICHODESMIUM SP.) POPULATIONS: ECOPHYSIOLOGICAL IMPLICATIONS. Journal of Phycology, 25: 773–784. doi: 10.1111/j.0022-3646.1989.00773.x
This work was supported by NSF grants OCE 85-00740, 88-20036 and BSR 86-14951. Cruise support was provided by E. J. Carpenter and D. G. Capone (OCE 87-10798, OEC 87-16907). The North Carolina Biotechnology Center (Project ARIG-881013) provided additional support. The technical assistance of H. Page and G. Suba is greatly appreciated. Editorial comments by R. Carlton, E. Carpenter, J. Priscu, and an anonymous reviewer helped improve the manuscript.
- Issue online: 29 OCT 2004
- Version of Record online: 29 OCT 2004
- algal-bacterial associations;
- heterotrophic bacteria;
- N2 fixation;
On three separate occasions we investigated morphological and physiological aspects of bacterial associations with planktonic aggregates of the ubiquitous marine N2 fixing cyanobacterium Trichodesmium sp. Close associations generally characterized Trichodesmium blooms; associations were present during day- and night-time. Colonization by both rod-shaped and filamentous heterotrophic bacteria occurred on Trichodesmiun aggregates actively fixing N2 (acetylene reduction). Scanning electron and optical microscopy showed bacteria located both around and within aggregates. Microautoradiography demonstrated that associated bacteria largely mediated utilization of trace additions of 3H-labeled carbohydrates (fructose, glucose, mannitol) and amino acids, whereas Trichodesmium utilized amino acids only. Oxygen measurements using microelectrodes revealed high localized oxygen consumption among aggregates, with rapid (within a minute) changes from supersaturated to subsaturated oxygen following the transition from photosynthetic illuminated to dark periods. Stab culturing techniques confirmed the presence of heterotrophic N2 fixers among aggregate-associated bacteria. Parallel deployment of oxygen microelectrodes, the tetrazolium salt 2,3,5 triphenyl tetrazolium chloride (TTC) and acetylene reduction assays demonstrated microaerophilic requirements for expression of nitrogenase activity among cultured bacteria.
Trichodesmium aggregates are characterized by dynamic nutrient and oxygen regimes, which promote and maintain simultaneous and contiguous oxygenic photosynthesis and N2 fixation. In part, the above-mentioned consortial interactions with a variety of heterotrophic bacteria facilitate Trichodesmium biomass production and bloom formation in nitrogen depleted, oligotrophic tropical/subtropical waters.