Urban endoliths: incidental microbial communities occurring inside concrete

Area of Science:

• Microbiology
• Environmental Science
• Materials Science

Background:

• Concrete is a ubiquitous synthetic material with significant environmental impact.
• The potential for concrete to host endolithic (rock-dwelling) microbial communities is largely unexplored.
• Endolithic microbes play crucial roles in various ecosystems and biogeochemical cycles.

Purpose of the Study:

• To investigate the presence and diversity of endolithic microbial communities within common concrete structures.
• To determine how concrete characteristics and environmental factors influence these microbial communities.
• To assess the viability and culturability of endolithic microbes found in concrete.

Main Methods:

• Collection of concrete samples from diverse structures in Lubbock, Texas.
• Application of multiple microbial life detection techniques: culture tests, DNA quantification, DNA amplification, and ATP assays.
• Analysis of internal (non-surface) concrete portions to identify endolithic life.

Main Results:

• A high prevalence of positive life detection results, indicating widespread endolithic microbial communities in concrete.
• Identification of bacteria, fungi, and archaea within concrete samples, with many microbes being viable and culturable.
• Significant variation in microbial signatures, with pre-cast units and underwater concrete showing higher endolith presence, linked to lower density and alkalinity.

Conclusions:

• Modern concrete structures commonly host diverse and viable endolithic microbial communities.
• Concrete's physical properties (density, alkalinity) and environmental context (e.g., submersion) significantly shape endolith communities.
• Further research on concrete endoliths is essential to understand their ecological significance in urbanized environments.