Relative abundance of Archaea and Bacteria along a thermal gradient of a shallow-water hydrothermal vent quantified by rRNA slot-blot hybridization.
Slot-blot hybridization of rRNA with domain-specific oligonucleotide probes targeting the 16S rRNA of Archaea and Bacteria was utilized to assess the relative abundance of these domains along a thermal gradient at a shallow submarine hydrothermal vent near Milos Island (Greece). The highest prokaryotic rRNA concentrations (defined as the sum of bacterial and archaeal rRNA) were found in the uppermost sediment surface (0-20 mm), decreasing strongly with depth. This indicates that the microbial activity was mainly occurring in the surface layer of this hydrothermal vent. Furthermore, rRNA concentrations were higher in regions closer to the vent, suggesting that the hydrothermal activity stimulated microbial activity. Archaea seemed to be a minor component of the microbial community at this vent site, even in the zones with higher temperatures. Bacteria made up at least 78% (mean 95%) of the prokaryotic rRNA. However, along the steepest temperature gradient, the proportion of archaeal rRNA increased. Nevertheless, even in the hottest sediment layer where a quantification was possible (in situ temperature 82 degrees C) archaeal rRNA made up only 11.9% of the prokaryotic rRNA. This suggests that Archaea were generally of minor importance at this vent site and were probably restricted to a narrow niche. The factors that allow Bacteria to dominate in a high temperature environment that was once believed to be the realm of Archaea remain elusive.
Sievert
Stefan M
SM
Departments of Microbiology and Biogeochemistry, and Molecular Ecology Group, Max-Planck-Institute for Marine Microbiology, Celsiusstr. 1, D-28359 Bremen, Germany123.
Ziebis
Wiebke
W
Departments of Microbiology and Biogeochemistry, and Molecular Ecology Group, Max-Planck-Institute for Marine Microbiology, Celsiusstr. 1, D-28359 Bremen, Germany123.
Kuever
Jan
J
Departments of Microbiology and Biogeochemistry, and Molecular Ecology Group, Max-Planck-Institute for Marine Microbiology, Celsiusstr. 1, D-28359 Bremen, Germany123.
Sahm
Kerstin
K
Departments of Microbiology and Biogeochemistry, and Molecular Ecology Group, Max-Planck-Institute for Marine Microbiology, Celsiusstr. 1, D-28359 Bremen, Germany123.
D001105:Archaea / Q000235:genetics* / Q000302:isolation & purification*; D001419:Bacteria / Q000235:genetics* / Q000302:isolation & purification*; D006115:Greece; D006358:Hot Temperature; D009693:Nucleic Acid Hybridization; D019642:RNA, Archaeal / Q000032:analysis / Q000235:genetics; D012329:RNA, Bacterial / Q000032:analysis / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D014871:Water Microbiology
D019642:RNA, Archaeal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S