Bacteriochlorophylls in Gliding Filamentous Prokaryotes from Hot Springs

WE have found bacteriochlorophyll-like pigments in two types of filamentous gliding prokaryotes that occur abundantly in alkaline hot springs. They are temporarily designated F-l and F-2. Representatives of F-2, found in hot springs of Iceland, Japan, New Zealand, Guatemala and the western United States, have been isolated in pure culture. They often exist as thick gelatinous mats up to about 70° C and are bright orange from the high content of carotenoids, but in North America they are normally covered by a layer of blue-green algae such as Synechococcus sp. Because of their colour and morphological characteristics, F-2 filaments were previously thought to be members of the heterotrophic, achlorophyllous flexibacteria^1,2. The trichomes are 0.5-1.0µm in diameter and of varying lengths. They are motile and glide on agar substrates at 45° C or 60° C at rates of 0.01-0.04µ/s (Fig. 1 A).