Preliminary Characterization of a Temperate Marine Member of the Chloroflexaceae

Abstract

Fossil records of the Precambrian era indicate that mat-forming phototrophic prokaryotes were some of the earth’s earliest Life forms (Schopf and Walter, 1963). Modern analogs of stromatolites (fossils of ancient mat communities) can be seen today in a number of extreme environments: salt marshes, hypersaline lakes and Lagoons, and thermal springs (Awramik, 1964). One organism of these communities, the phototrophic prokaryote Chloroflexus, has been shown to be a likely descendent of early phototrophic bacteria on the basis of morphological (Olson and Pierson, 1967) and phylogenetic studies (Stackebrandt, 1985). To date, only a thermophilic species of Chloroflexus, Cf. aurantiacus, has been maintained in pure culture and characterized (Pierson and Castenhotz, 1974; CastenhoLz and Pierson, 1961). One mesophilic fresh-water strain was isolated, but the culture has not been maintained (Gorlenko, 1975). Chloroflexus-like organisms have been observed and identified by morphology in a number of temperate marine and hypersaline environments: in Baja Mexico (Stolz, 1984; D’Amelio, 1987), Shark Bay, Western Australia (unpublished observation, BKP), Solar Lake, Sinai (Cohen, 1984), and Great Sippewissett Salt Marsh, Cape Cod, MA. Chloroflexus has been clearly Identified from the Baja and Solar Lake sites by electron microscopy (D’Amelio, 1987; Cohen, 1984). Little is known about its physiology or ecology. An analysis of the morphology, pigmentation, ecology and ultrastructure of the ChlorofIexus like organism of Great Sippewissett Salt Marsh, MA, is reported here.