Co-culturing microalgae with endophytic bacteria increases nutrient removal efficiency for biogas purification

Area of Science:

• Microbiology
• Environmental Science
• Biotechnology

Background:

• Endophytic bacteria reside within plant tissues, forming symbiotic relationships.
• Microalgae are utilized in wastewater treatment and biogas production.
• Investigating microalgal-bacterial consortia for environmental applications is an emerging field.

Purpose of the Study:

• To evaluate the suitability of an endophytic bacteria-Chlorella vulgaris symbiotic system for purifying biogas and biogas slurry.
• To assess the impact of endophytic bacteria on microalgae growth and physiological performance.
• To determine optimal conditions for microalgal-bacterial co-culture for wastewater treatment.

Main Methods:

• Isolation and identification of endophytic bacteria from Chlorella vulgaris.
• Co-culturing selected endophytic bacterial strains (S395-1, S395-2) with Chlorella vulgaris.
• Measuring microalgae growth rate, photosynthetic performance, carbonic anhydrase activity, and nutrient removal efficiency.
• Optimizing bacteria-to-microalgae ratio and co-culture duration.

Main Results:

• Both endophytic strains S395-1 and S395-2 promoted microalgae growth and improved photosynthetic performance.
• Optimal co-culture conditions (10:1 bacteria-to-microalgae ratio, 7 days) yielded high growth rates and carbonic anhydrase activity.
• The symbiotic system achieved high removal efficiencies for chemical oxygen demand (88.29%), nitrogen (88.31%), phosphorus (88.21%), and CO2 (68.13%).

Conclusions:

• Endophytic bacteria can form a beneficial symbiotic relationship with Chlorella vulgaris.
• The microalgal-bacterial consortium is effective for purifying biogas slurry and enhancing wastewater treatment.
• This study provides a framework for developing microalgal-bacterial consortia for improved biogas quality and environmental remediation.