Organic carbon enhances dark survival of the cyanobacterium Geitlerinema sp. Isolated from black band disease of corals

Abstract

Black band disease (BBD) of corals is characterized as a pathogenic, horizontally migrating microbial mat that is dominated by gliding, filamentous cyanobacteria. These cyanobacteria are important in BBD etiology in that they form the dense matrix of the band and are the source of a cyanotoxin that contributes to BBD pathogenesis. The BBD environment is chemically dynamic, fluctuating between oxic and anoxic conditions, and often contains high levels of sulfide. Additionally, it is nutrient and organic carbon rich due to the presence of actively lysing coral tissue and coral mucus. BBD cyanobacteria are physiologically adapted to the BBD environment in both light and darkness. Previous work has shown that BBD cyanobacteria can perform sulfide-insensitive oxygenic photosynthesis during the day. We report here the results of laboratory studies of a culture of the BBD cyanobacterium Geitlerinema sp. aimed at investigating metabolism during darkness. This isolate exhibited enhancement of survival supported by exogenous organic carbon sources (both sugars and amino acids) during darkness under both aerobic and anaerobic conditions, with the greatest effect seen under anaerobic conditions. Thus this BBD cyanobacterium is physiologically adapted to the anaerobic, organic rich environment of BBD at night as well as the sulfide-rich, illuminated band environment during the day. Rev. Biol. Trop. 56 (Suppl. 1): 119-126. Epub 2008 May 30.