Interactions between Microcystis and its associated bacterial community on electron transfer and transcriptomic...

Area of Science:

• Microbiology
• Environmental Science
• Bioenergetics

Background:

• Microcystis and bacteria coexist within the mucilage of Microcystis colonies.
• Extracellular electron transfer between these microorganisms converts bioenergy into electric energy.

Purpose of the Study:

• To elucidate the electron transfer mechanisms between Microcystis and bacteria using photosynthetic microbial fuel cells (PMFCs).
• To investigate the role of microbial interactions in energy transformation.

Main Methods:

• Construction and analysis of photosynthetic microbial fuel cells (PMFCs) with co-cultures of Microcystis and bacteria.
• Transcriptome and meta-transcriptome analyses to study gene expression.
• Confirmatory experiments involving riboflavin addition.

Main Results:

• Co-culturing Microcystis and bacteria resulted in a 2.5-fold increase in current density compared to pure Microcystis cultures.
• Photosynthesis efficiency in Microcystis was upregulated, leading to increased electron release.
• Bacterial communities showed enhanced oxidative phosphorylation and electron transfer via the type II secretion system (VgrG, IcmF).
• Direct contact via filamentous structures and increased riboflavin production by Microcystis facilitated electron transfer.

Conclusions:

• Direct contact and indirect interspecies electron transfer processes were confirmed between Microcystis and bacteria.
• Riboflavin acts as a crucial mediator in enhancing extracellular electron transfer and current density.
• Findings deepen the understanding of Microcystis colony activities during cyanobacterial blooms and microbial energy transformation.