Physiological and transcriptomic analyses to determine the responses to phosphorus utilization in Nostoc sp

Area of Science:

• Environmental microbiology
• Algal physiology
• Biochemistry

Background:

• Phosphorus (P) is a key nutrient limiting algal growth in aquatic ecosystems.
• Understanding how cyanobacteria utilize different phosphorus sources is vital for aquatic ecosystem management.
• Nostoc sp. is a widespread cyanobacterium found in various environmental conditions.

Purpose of the Study:

• To investigate the growth, phosphorus uptake and utilization, photosynthesis, and gene expression of Nostoc sp. under different phosphorus conditions.
• To compare the effects of organic phosphorus compounds (β-glycerol phosphate and 2-aminoethylphosphonic acid) versus inorganic phosphorus (orthophosphate) and a phosphorus-free medium.
• To elucidate the molecular mechanisms underlying Nostoc sp.'s response to varied phosphorus availability.

Main Methods:

• Culturing Nostoc sp. in media with β-glycerol phosphate, 2-aminoethylphosphonic acid, orthophosphate, or no phosphorus.
• Measuring growth rates, photosynthetic efficiency, and phosphorus uptake.
• Analyzing transcriptome profiles to assess gene expression changes.

Main Results:

• Phosphorus-free (NP) medium and 2-aminoethylphosphonic acid (2-amin) treatments negatively impacted Nostoc sp. growth and photosynthesis.
• NP and 2-amin treatments induced the expression of genes related to antioxidation and stress responses.
• No significant differences in growth, photosynthesis, or phosphorus utilization were observed between β-glycerol phosphate (β-gly) and orthophosphate treatments.

Conclusions:

• Nostoc sp. exhibits a remarkable flexibility in utilizing diverse phosphorus sources, including organic forms.
• This P-utilization flexibility contributes to the widespread distribution of Nostoc sp. in various environments.
• The study highlights the importance of considering organic phosphorus compounds in aquatic nutrient cycling and algal bloom dynamics.