Glycerol Utilization By Phytoplankton¹.

Area of Science:

• Marine biology
• Microbial ecology
• Biochemistry

Background:

• Dissolved organic carbon (DOC) is a key nutrient for marine microbes.
• Phytoplankton's ability to utilize DOC, specifically glycerol, remains largely uncharacterized.
• Understanding glycerol metabolism in phytoplankton is crucial for marine carbon cycling.

Purpose of the Study:

• To investigate the capacity of diverse marine phytoplankton to utilize glycerol as a carbon source.
• To explore the genetic and molecular basis of glycerol utilization in phytoplankton.
• To assess the ecological implications of glycerol availability for phytoplankton communities.

Main Methods:

• Genomic and transcriptomic analysis of glycerol transporter genes in phytoplankton.
• Screening of 31 phytoplankton strains from six phyla for glycerol utilization.
• Axenic culture experiments to determine glycerol utilization efficiency and growth responses.

Main Results:

• Widespread presence and expression of glycerol transporter genes were observed across phytoplankton.
• Phytoplankton showed diverse responses to glycerol: utilization (Type I), no response (Type II), and inhibition (Type III).
• Five species demonstrated intrinsic glycerol utilization independent of bacterial symbionts, correlating with gene expression.

Conclusions:

• Glycerol can serve as a carbon source, a neutral compound, or a growth inhibitor for phytoplankton.
• Phytoplankton glycerol transporters may have evolved diverse functions beyond uptake.
• Glycerol influences marine phytoplankton community structure, particularly under conditions of low photosynthetic efficiency.