Isolation, identification and characterization of an electrogenic microalgae strain.

Area of Science:

• Microbiology
• Electrochemistry
• Biotechnology

Background:

• Extracellular electron transfer (EET) is crucial for microbial environmental communication.
• Limited research exists on microalgal EET mechanisms and suitable model organisms.

Purpose of the Study:

• To isolate and characterize microalgae for extracellular electron transfer.
• To identify a model microalga for studying EET mechanisms.
• To evaluate the electrochemical performance of potential microalgal candidates.

Main Methods:

• Isolation and phylogenetic analysis of nine green microalgae species from wastewater.
• Electron microscopy for microalgal identification.
• Electrochemical testing (cyclic voltammetry, chronoamperometry) to assess electron transfer capabilities.
• Dissolved oxygen concentration measurements in microalgal biofilms.

Main Results:

• One microalga species, identified as Desmodesmus sp., demonstrated direct and indirect extracellular electron transfer.
• Desmodesmus sp. functioned as a cathodic microorganism, achieving stable current densities up to 170 mA m⁻² at -0.4 V under illumination.
• Oxygen concentration gradients were observed in the microalgal biofilm, indicating its role in indirect electron transfer.

Conclusions:

• Desmodesmus sp. is a promising model microalga for investigating extracellular electron transfer mechanisms.
• This study expands the known diversity of exoelectrogens and their applications.
• The findings contribute to understanding microalgal-based bioelectrochemical systems.