Distinct bacterial communities exist beneath a high Arctic polythermal glacier

Area of Science:

• Glaciology
• Microbiology
• Environmental Science

Background:

• Bacterial communities inhabit diverse glacial environments, including supraglacial, subglacial, and proglacial zones.
• Understanding the origin and distinctness of subglacial microbial communities is crucial for glacial ecosystem research.

Purpose of the Study:

• To investigate the relationship between subglacial, supraglacial, and proglacial bacterial communities at John Evans Glacier.
• To determine if the subglacial bacterial community is derived from surface or proglacial environments.

Main Methods:

• Terminal restriction fragment length polymorphism (T-RFLP) analysis of bacterial 16S rRNA genes.
• Analysis of bacterial communities in basal ice, sediment, and meltwater from different glacial zones.
• Chemical analysis of water and melted ice samples.

Main Results:

• Subglacial bacterial communities (water, ice, sediment) were distinct from supraglacial and proglacial communities.
• Only 8 out of 142 unique terminal restriction fragments (T-RFs) were found across all three environments.
• Supraglacial waters showed some overlap with subglacial communities, indicating meltwater influence.

Conclusions:

• The subglacial bacterial community at John Evans Glacier is predominantly autochthonous (originating internally) and adapted to subglacial conditions.
• Distinct chemical properties differentiate glacial environments, correlating with distinct microbial communities.
• While some bacterial types may be widespread, physically and chemically distinct glacial habitats harbor unique microbial life.