The Study of a Recent Iron-Encrusted Biofilm in the Marine Environment

Abstract

Intimate associations of microorganisms with ferric iron deposits are widespread in nature. Such microbial communities occur in fresh and saltwater environments, in soils and in desert rock varnishes (for reviews see Ghiorse 1984 and Konhauser 1998). In saltwater environments, these communities are often remote and therefore difficult to study. In the pelagic zone they have mostly been reported in sinking particles below 100 meters (Cowen & Silver 1984), and in the deep-sea they have been found in ferromanganese concretions (Burnett & Nealson 1981) and in some microbial mats (Karl et al. 1989, Juniper & Tebo 1995). In a few cases, epibiotic ferric iron-encrusted microbial communities have been studied on deep-sea mussel and limpet shells as well as worm tubes (Jannasch & Wirsen 1981, Baross & Deming 1985). Iron-encrusted microbial communities have also been reported in reef caves (Reitner et al. 2000). Generally speaking, very little is known about the community fine structure or the specific role that the microorganisms play in iron oxidation and/or deposition.