Electrochemical and microbial monitoring of multi-generational electroactive biofilms formed from mangrove sediment

• The performance in three-electrode devices exceeded 10 A/m2.
• Desulfuromonas species settled as predominant bacterium through the generations.
• The electrical performance loss was correlated with lower bacterial diversity.
• Miseq data and Mothur analysis were combined to understand biofilm evolution.

Electroactive biofilms were formed from French Guiana mangrove sediments for the analysis of bacterial communities' composition. The electrochemical monitoring of three biofilm generations revealed that the bacterial selection occurring at the anode, supposedly leading microbial electrochemical systems (MESs) to be more efficient, was not the only parameter to be taken into account so as to get the best electrical performance (maximum current density). Indeed, first biofilm generations produced a stable current density reaching about 18 A/m2 while second and third generations produced current densities of about 10 A/m2. MES bacterial consortia were characterized thanks to molecular biology techniques: DGGE and MiSeq® sequencing (Illumina®). High-throughput sequencing data statistical analysis confirmed preliminary DGGE data analysis, showing strong similarities between electroactive biofilms of second and third generations, but also revealing both selection and stabilization of the biofilms.