PNNL

Abstract

The aggregation of syntrophic Geobacter metallireducens and Geobacter sulfurreducens is known to be beneficial for enhancing direct interspecies electron transfer (DIET). However, the chemical speciation of such co-cultured communities was unclear. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used to characterize biological samples relevant to aggregates of Geobacter, including G. metallireducens and G. sulfurreducens single cultures in planktonic, biofilms formed from either the single bacteria or both, and co-cultures of these two strains in planktonic and aggregate forms. By using principle component analysis (PCA), the syntrophic Geobacter communities were significantly distinguished from their planktonic cells by a series of characteristic peaks such as amino acids, fatty acids/lipids, and quorum sensing signal molecules, indicating a different chemical composition and structure formed on their surfaces. Additionally, insights of co-culture community dynamics were obtained from a new perspective . These first SIMS results demonstrate that proteins played an important role in microbial communications.