AME 66:295-300 (2012)  -  DOI: https://doi.org/10.3354/ame01578

ABSTRACT: Members of the genus Thioploca are uncultured filamentous sulfur-oxidizing bacteria that live in freshwater/brackish sediments and have the ability to store nitrate in high concentrations in their cells. Their close relatives that inhabit marine sediments, such as Thiomargarita and ‘Candidatus Marithioploca’, are thought to greatly influence cycles of sulfur, nitrogen, and phosphorus. To date, the genus Thioploca has been reported only from temperate and subarctic areas. Our demonstration of Thioploca in Lake Tonle Sap, Cambodia, is the first report of this genus in a tropical lake. The filaments obtained from Lake Tonle Sap were morphologically similar to those of other lakes. Phylogenetic analysis based on genes for 16S rRNA, 23S rRNA, and the 16S-23S rRNA internal transcribed spacer (ITS) region revealed that 3 distinct lineages coexist in this lake. These results indicate that the geographical distribution and phylogenetic diversity of the genus Thioploca is greater than previously thought.

KEY WORDS: Sulfur-oxidizing bacteria · Freshwater lake · Sediment · Phylogeny