Visualizing and isolating iron-reducing microorganisms at single cell level

Abstract

Iron-reducing microorganisms (FeRM) play key roles in many natural and engineering processes. Visualizing and isolating FeRM from multispecies samples are essential to understand the in-situ location and geochemical role of FeRM. Here, we visualized FeRM by a “turn-on” Fe2+-specific fluorescent chemodosimeter (FSFC) with high sensitivity, selectivity and stability. This FSFC could selectively identify and locate active FeRM from either pure culture, co-culture of different bacteria or sediment-containing samples. Fluorescent intensity of the FSFC could be used as an indicator of Fe2+ concentration in bacterial cultures. By integrating FSFC with a single cell sorter, we obtained three FSFC-labeled cells from an enriched consortia and all of them were subsequently evidenced to be capable of iron-reduction and two unlabeled cells were evidenced to have no iron-reducing capability, further confirming the feasibility of the FSFC.ImportanceVisualization and isolation of FeRM from samples containing multispecies are commonly needed by researchers from different disciplines, such as environmental microbiology, environmental sciences and geochemistry. However, no available method has been reported. In this study, we provid a solution to visualize FeRM and evaluate their activity even at single cell level. Integrating with single cell sorter, FeRM can also be isolated from samples containing multispecies. This method can be used as a powerful tool to uncover the in-situ or ex-situ role of FeRM and their interactions with ambient microbes or chemicals.

Function-Oriented Graphene Quantum Dots Probe for Single Cell in situ Sorting of Active Microorganisms in Environmental Samples

“…The fluorescence signal was first observed under LSCM, and the fluorescence of the bacteria was estimated. The selected bacteria were then ejected using a laser beam controlled by PRECI SCS software ( Gan et al, 2020 ). After the bacteria were sorted, they were transferred to LB medium for large-scale culturing.…”

Coupled magnetic nanoparticle‐mediated isolation and single‐cell image recognition to detect Bacillus' cell size in soil

“…Here, the combination of MMI and SCIR approach in our study makes it possible to focus on the single‐cell level. This improvement is beneficial for the integration of downstream analysis with microbial morphology (Chen et al, 2021; Gan et al, 2021). Therefore, the established experimental and analytical methods are based on MMI.…”

“…Furthermore, single‐cell image recognition (SCIR) was developed as a prospective technology to investigate the morphology of the active microbes isolated by MMI. Gan et al (2021) successfully identified and located active iron‐reducing microorganisms from both pure culture and sediment‐containing samples by coupling fluorescent and chemosensor confocal laser scanning microscopy at the single‐cell level. However, coupling MMI and SCIR for visualisation of active functional microorganisms and evaluation of their size even at the single‐cell level is still lacking in studies of the soil ecosystem.…”