Microbial community structure and biomass in developing drinking water biofilms

Area of Science:

• Microbiology
• Environmental Science
• Water Quality

Background:

• Traditional microbial analysis methods lack ecological insights for drinking water systems.
• Understanding microbial community structure and biomass is crucial for drinking water safety.
• Biofilms play a significant role in microbial dynamics within distribution networks.

Purpose of the Study:

• To compare microbial community structure and biomass in drinking water biofilms from two Finnish distribution systems.
• To investigate the influence of water residence time and biofilm development time on microbial ecology.
• To assess differences possibly linked to raw water quality and treatment processes.

Main Methods:

• Analysis of phospholipid fatty acid methyl esters (PLFAs) and lipopolysaccharide 3-hydroxy fatty acid methyl esters (LPS 3-OH-FAs) in biofilms.
• Sampling from two distinct drinking water distribution systems (A and B).
• Evaluation of microbial community structure and biomass relative to water residence and development times.

Main Results:

• Microbial communities showed stability across distribution systems, with minor effects from water residence time.
• Biofilm microbial community complexity in system A decreased with longer development times (6 vs. 23/40 weeks).
• Viable microbial biomass (estimated by PLFAs) increased with water residence time in both systems.
• LPS 3-OH-FAs increased with biofilm development time in system B, but were below detection in system A.

Conclusions:

• Drinking water microbial communities are relatively stable but distinct between different distribution systems.
• Biofilm development time significantly impacts microbial community structure, particularly in younger biofilms.
• Water residence time is a key factor influencing viable microbial biomass in drinking water biofilms.