Relic DNA obscures bacterial diversity and interactions in ballast tank sediment

Area of Science:

• Microbiology
• Environmental Science
• Molecular Biology

Background:

• Ballast tank sediment (BTS) contains abundant relic DNA, complicating microbial diversity assessments.
• The influence of relic DNA on microbial community structure in BTS is not well understood.
• Accurate microbial profiling is essential for effective BTS management and environmental risk assessment.

Purpose of the Study:

• To investigate the impact of relic DNA on microbial diversity estimates in BTS.
• To differentiate between total and viable bacterial communities in BTS using propidium monoazide (PMA) treatment.
• To assess the implications of relic DNA for microbial community assembly and risk assessment in BTS.

Main Methods:

• Propidium monoazide (PMA) treatment was used to distinguish between viable and non-viable (relic) DNA.
• 16S amplicon high-throughput sequencing was employed to characterize bacterial communities.
• Bioinformatic analyses were performed to assess changes in species richness, operational taxonomic units (OTUs), and relative abundances.

Main Results:

• Relic DNA is a significant component of BTS, affecting diversity estimates.
• PMA treatment resulted in variable changes in species richness (3.15% increase to 37.52% decrease) and OTU presence (6.27%-15.79% reduction).
• Relic DNA removal altered taxon relative abundances, facilitated rare taxa detection, and led to overestimation of community network properties.

Conclusions:

• Relic DNA significantly obscures microbial diversity and risk assessments in BTS.
• Accurate assessment of viable bacteria is critical for effective ballast sediment management.
• The study underscores the necessity of accounting for relic DNA in environmental microbial studies.