title: Surface display of roGFP for monitoring redox status of extracellular microenvironments in Shewanella oneidensis biofilms.
abstract: Biofilms are the most ubiquitous and resilient form of microbial life on earth. One most important feature of a biofilm is the presence of a self-produced matrix, which creates highly heterogeneous and dynamic microenvironments within biofilms. Redox status in biofilm microenvironments plays a critical role in biofilm development and function. However, there is a lack of non-intrusive tools to quantify extracellular redox status of microenvironments within a biofilm matrix. In this study, using Shewanella oneidensis as a model organism, we demonstrated a novel approach to monitor extracellular redox status in biofilm microenvironments. Specifically, we displayed a redox sensitive fluorescence protein roGFP onto the cell surface of S. oneidensis by fusing it to the C-terminus of BpfA, a large surface protein, and used the surface displayed roGFP as a sensor to quantify the extracellular redox status in the matrix of S. oneidensis biofilms. The fusion of roGFP into BpfA has no negative impacts on cell growth and biofilm formation. Upon exposure to oxidizing agents such as H2 O2 , Ag(+) , and SeO3 (2-) , S. oneidensis BpfA-roGFP cells exhibited a characteristic fluorescence of roGFP. Proteinase treatment assay and super-resolution structured illumination microscopy confirmed the surface localization of BpfA-roGFP. We further used the surface displayed roGFP monitored the extracellular redox status in the matrix at different depths of a biofilm exposed to H2 O2 . This study provides a novel approach to non-invasively monitor extracellular redox status in microenvironments within biofilms, which can be used to understand redox responses of biofilms to environmental perturbations.
authors.affiliation: Singapore Centre on Environmental Life Science Engineering, Nanyang Technological University, Singapore, 637551, Singapore; Interdisciplinary Graduate School, Nanyang Technological University, Singapore.
authors.forename: Krishnakumar
authors.initials: K
authors.lastname: Sivakumar
authors.forename: Manisha
authors.initials: M
authors.lastname: Mukherjee
authors.forename: Hsin-I
authors.initials: HI
authors.lastname: Cheng
authors.forename: Yingdan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lianghui
authors.initials: L
authors.lastname: Ji
authors.forename: Bin
authors.initials: B
authors.lastname: Cao
mesh_terms: D018441:Biofilms; D015374:Biosensing Techniques / Q000379:methods*; D061505:Cell Surface Display Techniques / Q000379:methods*; D005110:Extracellular Space / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020592:Shewanella / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins
keywords: EPS; Shewanella oneidensis; biofilm matrix; microenvironment; surface display