Interactions between polyethylene and polypropylene microplastics and Spirulina sp. microalgae in aquatic systems

Area of Science:

• Environmental Microbiology
• Bioremediation
• Microplastic Degradation

Background:

• Microplastic pollution poses a significant threat to aquatic ecosystems.
• Spirulina sp. is a widely studied microalga with potential applications in various fields.
• The interaction between microplastics and microalgae is not fully understood.

Purpose of the Study:

• To investigate the effects of polyethylene (PE) and polypropylene (PP) microplastics on Spirulina sp. growth and phycocyanin content.
• To evaluate the capability of Spirulina sp. in degrading PE and PP microplastics.

Main Methods:

• Culturing Spirulina sp. with PE and PP microplastics (500 mg/500 mL, 0.5-1 mm²).
• Monitoring Spirulina sp. growth via optical density for 30 days.
• Extracting phycocyanin and analyzing protein content.
• Utilizing Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) for cell and microplastic analysis.
• Employing Energy-dispersive X-ray spectroscopy (EDX) for elemental analysis of microplastics.

Main Results:

• Spirulina sp. growth rate significantly decreased (p < 0.05) in the presence of PE and PP microplastics.
• Microplastic exposure caused surface damage to Spirulina sp. cells and altered protein functional groups.
• Phycocyanin yield and protein content in Spirulina sp. were reduced by microplastic treatment.
• FTIR and EDX analyses indicated degradation of PE and PP microplastics by Spirulina sp. culture, evidenced by changes in functional groups and decreased carbon content.

Conclusions:

• Microplastics adversely affect Spirulina sp. biomass production and phycocyanin yield.
• Spirulina sp. exhibits potential for the biodegradation of PE and PP microplastics.
• Further research is warranted to optimize this bioremediation process.