Persistent flocks of diverse motile bacteria in long-term incubations of electron-conducting cable bacteria, Candidatus Electronema aureum

Frontiers in Microbiology

Microbiology

Ian P. G. Marshall¹  Andreas Schramm¹  Jamie J. M. Lustermans¹  Lars Peter Nielsen¹  Laurine D. W. Burdorf²  Jesper J. Bjerg² 

[1] Section for Microbiology, Department of Biology, Center for Electromicrobiology, Aarhus University, Aarhus, Denmark;Section for Microbiology, Department of Biology, Center for Electromicrobiology, Aarhus University, Aarhus, Denmark;Department of Biology, Microbial Systems Technology Excellence Centre, University of Antwerp, Wilrijk, Belgium;

关键词: flocking;    cable bacteria;    electron conduction;    succession;    interspecies electron transfer;    time series;    microprofiles;   

DOI  :  10.3389/fmicb.2023.1008293

 received in 2022-07-31, accepted in 2023-02-06,  发布年份 2023

来源: Frontiers

【 摘 要 】

Cable bacteria are centimeters-long filamentous bacteria that oxidize sulfide in anoxic sediment layers and reduce oxygen at the oxic-anoxic interface, connecting these reactions via electron transport. The ubiquitous cable bacteria have a major impact on sediment geochemistry and microbial communities. This includes diverse bacteria swimming around cable bacteria as dense flocks in the anoxic zone, where the cable bacteria act as chemotactic attractant. We hypothesized that flocking only appears when cable bacteria are highly abundant and active. We set out to discern the timing and drivers of flocking over 81 days in an enrichment culture of the freshwater cable bacterium Candidatus Electronema aureum GS by measuring sediment microprofiles of pH, oxygen, and electric potential as a proxy of cable bacteria activity. Cable bacterial relative abundance was quantified by 16S rRNA amplicon sequencing, and microscopy observations to determine presence of flocking. Flocking was always observed at some cable bacteria, irrespective of overall cable bacteria rRNA abundance, activity, or sediment pH. Diverse cell morphologies of flockers were observed, suggesting that flocking is not restricted to a specific, single bacterial associate. This, coupled with their consistent presence supports a common mechanism of interaction, likely interspecies electron transfer via electron shuttles. Flocking appears exclusively linked to the electron conducting activity of the individual cable bacteria.

【 授权许可】

Unknown   
Copyright © 2023 Lustermans, Bjerg, Burdorf, Nielsen, Schramm and Marshall.