Prokaryote diversity and taxonomy: current status and future challenges

Area of Science:

• Microbiology
• Genomics
• Environmental Science

Background:

• Prokaryotes (Bacteria and Archaea) are the most abundant and metabolically diverse organisms on Earth.
• Current species classification relies on genomic and phenotypic properties, with a broad 70% DNA-DNA similarity cut-off.
• The known number of prokaryotic species (around 6200) is a significant underestimate of actual diversity.

Purpose of the Study:

• To highlight the vast, underestimated diversity of prokaryotic life.
• To discuss the limitations of current prokaryote classification and culturing methods.
• To emphasize the need for innovative approaches to capture prokaryotic diversity.

Main Methods:

• Review of current prokaryote classification standards (DNA-DNA similarity).
• Analysis of small-subunit ribosomal DNA (rDNA) characterization for community assessment.
• Discussion of limitations in classic culturing techniques for environmental bacteria.

Main Results:

• Prokaryotic species diversity is at least two orders of magnitude greater than currently named species.
• Traditional culturing methods fail to recover many abundant environmental prokaryotes.
• Novel isolation methods are emerging for environmentally significant organisms.

Conclusions:

• A significant gap exists between recognized and actual prokaryotic diversity.
• Innovative cultivation and characterization techniques are crucial for understanding microbial ecosystems.
• Adequate funding is essential to support research into prokaryotic diversity.