| SS4.02 Ecology and Physiology of Marine Organisms: Insights from Genes, Genomes, and Proteomes |
| Horak, R, E, College of William and Mary, Williamsburg, USA, rehora@wm.edu |
| Forsyth, M, H, College of William and Mary, Williamsburg, USA, mhfors@wm.edu |
| Van Dover, C, L, College of William and Mary, Williamsburg, USA, clvand@wm.edu |
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| LIGHT PRODUCTION BY SULFIDE-OXIDIZING BACTERIA? A POSSIBLE LIGHT SOURCE FOR CHLOROPLAST-SEQUESTERING FORAMINIFERANS |
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| Functional chloroplasts are sequestered in foraminiferans inhabiting the benthos well below the euphotic zone. The foraminiferans Nonionella stella (Santa Barbara Basin, 600 m) and Virgulinella fragilis (Cariaco Basin, 550 m) live within Beggiatoa spp. mats, a genus of sulfide-oxidizing bacteria, and sequester chloroplasts (Bernhard and Bowser 1999, Bernhard 2003). V. fragilis also harbors sulfide-oxidizing bacterial endosymbionts. In the absence of sunlight at these depths, the benefit of the chloroplasts is unclear, although they have been implicated in helping the foraminiferans meet nitrogen requirements (Grzymski et al. 2002). The close association of Beggiatoa spp. mats and bacterial endosymbionts to sequestered chloroplasts, together with the fact that bioluminescence evolved at least once in bacteria (family Vibrionaceae), lead us to the hypothesis that sulfide-oxidizing bacteria may emit light that can be a source of photosynthetically active radiation. To begin to test this hypothesis, we assayed for indicators of bacterial bioluminescence using pure cultures of sulfide-oxidizing bacteria. Light production was measured directly under multiple culture conditions, and the presence of the luxA gene, necessary for bacterial bioluminescence, was tested by molecular techniques. |
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