Abstract
Reef-building corals harbor various bacteria whose biological significance for corals remains obscure. Here we report a novel cyanobacterium that has been found within the skeleton of reef-building corals. We have successfully isolated a filamentous cyanobacterium that inhabits within the skeleton of Goniastrea aspera, a massive reef-building coral. Characteristics of the filamentous cyanobacterium are: (1) 1μm in diameter, (2) nonheterocyst-forming, and (3) Chl a as the sole chlorophyll pigment. 16S rDNA analysis has affiliated the filamentous cyanobacterium with Halomicronema sp., a genera that has recently been identified in benthic microbial mats in a hypersaline pond. The biological interaction between Halomicronema sp. and the host coral is discussed in terms of a new symbiotic relationship.
