Abstract
Beggiatoaceae, giant sulphur-oxidizing bacteria, are well known to occur in cold and temperate waters, as well as hydrothermal vents, where they form dense mats on the floor. However, they have never been described in tropical marine mangroves. Here, we describe two new species of benthic Beggiatoaceae colonizing a marine mangrove adjacent to mangrove roots. We combined phylogenetic and lipid analysis with electron microscopy in order to describe these organisms. Furthermore, oxygen and sulphide measurements in and ex situ were performed in a mesocosm to characterize their environment. Based on this, two new species, Candidatus Maribeggiatoa sp. and Candidatus Isobeggiatoa sp. inhabiting tropical marine mangroves in Guadeloupe were identified. The species identified as Candidatus Maribeggiatoa group suggests that this genus could harbour a third cluster with organisms ranging from 60 to 120 μm in diameter. This is also the first description of an Isobeggiatoa species outside of Arctic and temperate waters. The multiphasic approach also gives information about the environment and indications for the metabolism of these bacteria. Our study shows the widespread occurrence of members of Beggiatoaceae family and provides new insight in their potential role in shallow-water marine sulphide-rich environments such as mangroves.
Highlights
Beggiatoa spp. are multicellular, filamentous colorless bacteria
Small vesicles can be observed in the cells and the external membrane appeared thicker due to the presence of a thin sheath which can be removed by critical point treatment in SEM observations
SEM (Fig. 3a) and Transmission Electron Microscopy (TEM) (Fig. 3c-d) observations showed that no external bacteria are encountered on the filament
Summary
Beggiatoa spp. are multicellular, filamentous colorless bacteria. Since their discovery by Vaucher in 1803, they are considered among the largest sulphur-oxidizing bacteria in nature [1].PLOS ONE | DOI:10.1371/journal.pone.0117832 February 17, 2015Large Beggiatoa Colonizing Marine MangroveMembers of this genus are widespread in marine and freshwater environments. Beggiatoa spp. are multicellular, filamentous colorless bacteria. Since their discovery by Vaucher in 1803, they are considered among the largest sulphur-oxidizing bacteria in nature [1]. Members of this genus are widespread in marine and freshwater environments. They often form mats on strongly reduced, organic or hydrocarbon-rich porous sediments, with sufficient interstitial space for motility [2]. Members of the Beggiatoaceae usually move by gliding motility [3] in order to respond to chemical signals [4]. They are usually found at the surface or within the top few centimeters of sulphide-rich sediments
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