Wiring Up Along Electrodes for Biofilm Formation

Dielectrophoresis for Isolating Low-Abundance Bacteria Obscured by Impurities in Environmental Samples

Bacterial communities associated with living organisms play critical roles in maintaining health and ecological balance. While dominant bacteria have been widely studied, understanding the role of low-abundance bacteria has become increasingly important due to their unique roles, such as regulating bacterial community dynamics and supporting host-specific functions. However, detecting these bacteria remains challenging, as impurities in environmental samples mask signals and compromise the accuracy of analyses. This study explored the use of dielectrophoresis (DEP) as a practical approach to isolate low-abundance bacteria obscured by impurities, comparing its utility to conventional centrifugation methods. Using two shrimp species, Neocaridina denticulata and Penaeus japonicus, DEP effectively isolated bacterial fractions while reducing impurities, enabling the detection of bacteria undetected in centrifuged samples. These newly detected bacteria were potentially linked to diverse ecological and host-specific functions, such as nutrient cycling and immune modulation, highlighting DEP as a highly potential approach to support the study of host-microbial interactions. Overall, we believe that DEP offers a practical solution for detecting overlooked bacteria in conventional methods and exploring their diversity and functional roles, with potential contributions to aquaculture and environmental biotechnology.

Evidences of the electrogenic sulfur oxidation in constructed wetlands

The sulfur redox cycling, mainly involving sulfide oxidation and sulfate reduction, remains a crucial factor that regulates the treatment performance of constructed wetlands (CWs). However, anoxic environments normally prevail in the CW systems, harboring vast reduced sulfur and sulfur minerals, where the occurrence and mechanism of anoxic sulfide oxidation remain unknown. In this study, CW microcosms filled with quartz sand (Qtz) and pyrite (Pyt) were established to investigate the anoxic sulfur oxidation under the bioelectrochemical manipulations. As a result, the δ34S-sulfate increased from 8.75 ± 0.29‰ in the influent to 51.74 ± 16.21‰ (Pyt) and 46.12 ± 25.95‰ (Qtz) at the anoxic zone under the open-circuit condition, and to 34.50 ± 6.99‰ (Pyt) and 42.53 ± 19.59‰ (Qtz) at that under the close-circuit conditions. This suggested the concurrent sulfate reduction and electrogenic sulfide oxidation in the systems. Based on a modified isotopic fractionation model, the electrogenic sulfide oxidation were further calculated (i.e., up to 87.58 and 265.13 mgS·m-2·d-1 in Qtz and Pyt, respectively). Results of fluorescence in situ hybridization and metagenomic analyses demonstrated the occurrence of filamentous bacteria belonging to Desulfobulbaceae, with relative abundances of 0.32 ± 0.00% and 0.88 ± 0.25% in the anoxic zones of Qtz and Pyt, respectively. Pyrite was found to upregulate the functional genes encoding microbial transformation of elemental sulfur, sulfide, and thiosulfate. Interspecies network analyses revealed mutual relationships between the filamentous bacteria and microorganisms involved in sulfur, iron, and carbon transformations. Together, this study provided new insights to the electrogenic sulfide oxidation in CWs.