Quinone profiles in lake sediments: Implications for microbial diversity and community structures

Area of Science:

• Environmental microbiology
• Biogeochemistry
• Analytical chemistry

Background:

• Microbial quinones are essential lipids involved in electron transport chains.
• Lake sediments harbor diverse microbial communities with varied metabolic potentials.
• Understanding quinone profiles provides insights into microbial community structure and function.

Purpose of the Study:

• To analyze the microbial quinone composition in Japanese lake sediment samples.
• To identify dominant quinone types and their implications for microbial populations.
• To assess the diversity and bioenergetic modes of sediment microbial communities.

Main Methods:

• Spectrochromatography and mass spectrometry were employed for quinone analysis.
• Sediment mud samples from five Japanese lakes were analyzed.
• Numerical analyses were performed on quinone profiles.

Main Results:

• Total quinone content varied from 1.97 to 18.0 nmol/g dry weight.
• Ubiquinones and menaquinones constituted 42-74% of total quinones.
• Plastoquinones and phylloquinone (photosynthetic quinones) comprised 26-58%.
• PQ-9 and Q-8 were the most abundant quinones in sediments.
• Sediment microbial communities were diverse but showed similar bioenergetic diversity across lakes.
• Higher proportions of photosynthetic quinones were observed in surface waters compared to sediments.

Conclusions:

• Oxygenic phototrophic microorganisms and Q-8-containing proteobacteria are major components of lake sediment microbial populations.
• The high abundance of oxygenic phototrophs in sediments likely results from sedimentation from surface waters.
• Lake sediments host a balanced microbial community with ubiquinone-mediated aerobic respiration, oxygenic photosynthesis, and menaquinone-associated respiration.