Novel division level bacterial diversity in a Yellowstone hot spring

Area of Science:

• Microbiology
• Molecular Biology
• Environmental Science

Background:

• Obsidian Pool (OP) in Yellowstone National Park is a hot spring.
• Previous research indicated high archaeal diversity in OP.
• The bacterial community composition was previously less understood.

Purpose of the Study:

• To conduct a culture-independent molecular phylogenetic survey of the bacterial community in Obsidian Pool.
• To identify novel bacterial lineages and assess bacterial diversity.
• To investigate the primary productivity base in the hot spring environment.

Main Methods:

• Small-subunit ribosomal DNA (rDNA) genes were amplified from sediment DNA using PCR.
• Cloning and restriction fragment length polymorphism (RFLP) were used to identify unique rDNA types.
• Sequencing of 122 representative rDNA clones and phylogenetic analysis were performed.

Main Results:

• 54 distinct bacterial sequence types were identified, with 70% affiliated with known divisions and 30% forming 12 novel candidate divisions.
• Sequences related to chemolithotrophic thermophiles (e.g., hydrogen-oxidizers, sulfate-reducers) were abundant.
• Unexpectedly, no archaeal sequences were detected in the bacterial clone libraries.

Conclusions:

• The bacterial community in Obsidian Pool exhibits significant diversity, including novel lineages.
• The presence of specific bacteria suggests a lithotrophic base for primary productivity, driven by hydrogen oxidation and sulfate reduction.
• The findings challenge the notion that Archaea dominate all hydrothermal environments, highlighting the importance of bacterial contributions.