Affiliation:
1. Department of Molecular Microbiology and Biotechnology,1 and
2. Department of Zoology and the Super-Center for Ecological and Environmental Studies,2 George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
Abstract
ABSTRACT
Laboratory aquarium experiments demonstrated that
Vibrio
strain AK-1 caused rapid and extensive bleaching of the coral
Oculina patagonica
at 29°C, slower and less-complete bleaching at 23°C, and no bleaching at 16°C. At 29°C, the application of approximately 100
Vibrio
strain AK-1 cells directly onto the coral caused 50 and 83% bleaching after 10 and 20 days, respectively. At 16°C, there was no bleaching, even with an initial inoculum of 1.2 × 10
8
bacteria. To begin to understand the effect of seawater temperature on bleaching of
O. patagonica
by
Vibrio
strain AK-1, adhesion of the bacteria to the coral as a function of temperature was studied. Inoculation of 10
7
Vibrio
strain AK-1 organisms into flasks containing 20 ml of seawater at 25°C and a fragment of
O. patagonica
resulted in net levels of bacterial adhesion to the coral of 45, 78, and 84% after 2, 6, and 8 h, respectively. The adhesion was inhibited 65% by 0.001%
d
-galactose and 94% by 0.001% methyl-β-
d
-galactopyranoside (β-M-Gal). After the incubation of
Vibrio
strain AK-1 with the coral for 6 h, 42% of the input bacteria were released from the coral with 0.01% β-M-Gal, compared to less than 0.2% when β-M-Gal was present during the adhesion step. Adhesion did not occur when
Vibrio
strain AK-1 was grown at 16°C, regardless of whether the corals were maintained at 16 or 25°C, whereas bacteria grown at 25°C adhered to corals maintained at 16 or 25°C. Bacteria grown at 25°C adhered avidly to Sepharose beads containing covalently bound β-
d
-galactopyranoside but failed to bind if grown at 16°C. These data suggest that elevated seawater temperatures may cause coral bleaching by allowing for the expression of adhesin genes of
Vibrio
strain AK-1.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
90 articles.
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