Wiring Bacterial Electron Flow for Sensitive Whole-Cell Amperometric Detection of Riboflavin

Abstract

A whole-cell bioelectrochemical biosensing system for amperometric detection of riboflavin was developed. A "bioelectrochemical wire" (BW) consisting of riboflavin and cytochrome C between Shewanella oneidensis MR-1 and electrode was characterized. Typically, a strong electrochemical response was observed when riboflavin (VB2) was added to reinforce this BW. Impressively, the electrochemical response of riboflavin with this BW was over 200 times higher than that without bacteria. Uniquely, this electron rewiring process enabled the development of a biosensing system for amperometric detection of riboflavin. Remarkably, this amperometric method showed high sensitivity (LOD = 2.2 nM, S/N = 3), wide linear range (5 nM ∼ 10 μM, 3 orders of magnitude), good selectivity, and high resistance to interferences. Additionally, the developed amperometric method featured good stability and reusability. It was further applied for accurate and reliable determination of riboflavin in real conditions including food, pharmaceutical, and clinical samples without pretreatment. Both the cost-effectiveness and robustness make this whole-cell amperometric system ideal for practical applications. This work demonstrated the power of bioelectrochemical signal amplification with exoelectrogen and also provided a new idea for development of versatile whole-cell amperometric biosensors.

Promoting Shewanella Bidirectional Extracellular Electron Transfer for Bioelectrocatalysis by Electropolymerized Riboflavin Interface on Carbon Electrode

“…The Mtr respiratory pathway in S. oneidensis MR-1 has been demonstrated to be functionally reversible and was able to conduct the inward electron flux from an electrode into periplasmic reductase for intracellular fumarate reduction (Ross et al, 2011). In addition, an increase in riboflavin concentration in electrolytes also dramatically improved the cathodic current consumption for fumarate reduction in S. oneidensis MR-1 (Yang et al, 2015; Si et al, 2016). Thus, these findings compel further study on the effect of polyriboflavin interface on inward EET processes and bioelectrocatalytic reduction of fumarate in Shewanella .…”

“…However, both CV curves of the two electrodes delivered undetectable reduction current in an electrochemical cell inoculated with ΔmtrC/undA mutant strain. According to previous reports (Si et al, 2015, 2016) and the CV results, a reducing potential of -0.6 V was employed to enable fumarate reduction in the following amperometric tests. In anaerobic three-electrode cells inoculated with wide-type S. putrefaciens CN32 strain, continuous amperometry measurements (Figure 4B) for both the PRF@CC-30 electrode and the CC electrode showed a sudden onset of cathodic current upon addition of 20 mM fumarate.…”

The Application of Whole Cell-Based Biosensors for Use in Environmental Analysis and in Medical Diagnostics

“…Excess intake of riboflavin can also be harmful and lead to oxidative damage in light-exposed tissue [ 89 , 90 ]. To address this, Si et al reported a whole cell bioelectrochemical biosensor system for the amperometric detection of riboflavin [ 91 ]. As shown in Figure 6 , a bioelectrochemical wire (BW) was made and consisted of riboflavin and cytochrome C strung between Shewanella oneidensis MR-1.…”

“…OM indicates the outer cell membrane; Cyto C represents cytochrome C proteins; and FccA indicates fumarate reductase. Reprinted with permission from [ 91 ].…”

Redox Electrochemistry to Interrogate and Control Biomolecular Communication

“…Similar to pyocyanin, previous work has demonstrated that these components can be transcriptionally regulated to create an AND logic gate for detecting QS signals ( Hu et al., 2015 ). Others have taken advantage of the ability of cytochromes to drastically enhance molecular redox cycling to detect sub-nanomolar concentrations of pyocyanin ( Yang et al., 2017 ) and riboflavin ( Si et al., 2016 ). Last, others have combined Shewanella oneidensis with other fuel cell species to detect metabolic secretions like lactate ( Zeng et al., 2019 ).…”