Phosphate insensitive aminophosphonate mineralisation within oceanic nutrient cycles

Area of Science:

• Marine microbiology
• Biogeochemical cycles

Background:

• Marine environments are often nutrient-poor, leading to intense competition and nutrient recycling.
• Organic phosphonates are abundant but typically require specific enzymes for breakdown.
• Previous research indicated phosphonate-degrading genes are Pho regulon-controlled and repressed by phosphate, suggesting recalcitrance.

Purpose of the Study:

• To investigate the catabolism of 2-aminoethylphosphonate in marine bacteria.
• To challenge the prevailing paradigm of phosphonate recalcitrance in marine ecosystems.
• To identify the regulatory mechanisms governing phosphonate degradation in the ocean.

Main Methods:

• Isolation of marine bacteria capable of mineralizing 2-aminoethylphosphonate.
• Analysis of gene regulation involved in phosphonate catabolism.
• Comparison of substrate-inducible versus Pho-regulated metabolic pathways.

Main Results:

• Marine bacteria can mineralize 2-aminoethylphosphonate, a common marine aminophosphonate.
• This mineralization occurs via substrate-inducible gene regulation.
• The catabolism is independent of the Pho regulon, which is typically repressed by inorganic phosphate.

Conclusions:

• Substrate-inducible, Pho-independent catabolism of 2-aminoethylphosphonate is a significant, previously unrecognized pathway in marine environments.
• This pathway represents a novel component of oceanic carbon, nitrogen, and phosphorus cycles.
• The findings necessitate a re-evaluation of phosphonate bioavailability and nutrient cycling in the ocean.