Microbial Biosensors for Rapid Determination of Biochemical Oxygen Demand: Approaches, Tendencies and Development Prospects

Abstract

One of the main indices of the quality of water is the biochemical oxygen demand (BOD). A little over 40 years have passed since the practical application of the first microbial sensor for the determination of BOD, presented by the Japanese professor Isao Karube. This time span has brought new knowledge to and practical developments in the use of a wide range of microbial cells based on BOD biosensors. At present, this field of biotechnology is becoming an independent discipline. The traditional BOD analysis (BOD₅) has not changed over many years; it takes no less than 5 days to carry out. Microbial biosensors can be used as an alternative technique for assessing the BOD attract attention because they can reduce hundredfold the time required to measure it. The review examines the experience of the creation and practical application of BOD biosensors accumulated by the international community. Special attention is paid to the use of multiple cell immobilization methods, signal registration techniques, mediators and cell consortia contained in the bioreceptor. We consider the use of nanomaterials in the modification of analytical devices developed for BOD evaluation and discuss the prospects of developing new practically important biosensor models.

Keywords: biochemical oxygen demand (BOD); biosensors; mediators; microbial fuel cell; organic and inorganic polymers.

Figure 1

(A) Schematic diagram of the BOD classical analysis [6]. Reprinted with permission from ref. [6]. Copyright © 2022 American Scientific Publishers; (B) schematic diagram of an amperometric biosensor.

Figure 2

Number of publications in the ScienceDirect database per year by the BOD biosensor and BOD sensor keywords.

Figure 3

Substrate specificities of receptor elements based on the co-cultures used. The change in biosensor’s receptor element substrate specificity upon addition of a new microorganism into the receptor is shown [13]. Reprinted with permission from ref. [13]. Copyright © 2022 Elsevier.

Figure 4

Three-electrode configuration of an electroactive film-based MFC reactor: WE, working electrode; RE, reference electrode; AE, auxiliary electrode [32]. Reprinted with permission from ref. [32]. Copyright© 2022 Elsevier.

Figure 5

Schematic representation of a BOD biosensor. An immobilized microbial population in combination with a Clark-type oxygen electrode [33]. Reprinted with permission from ref. [33]. Copyright© 2022 Elsevier.

Figure 6

Schematic of a bioelectrochemical reactor used as a BOD sensor [34]. Reprinted with permission from ref. [34]. Copyright© 2022 Elsevier.

Figure 7

Schematic process of a reactor-type BOD biosensor system [37]. Reprinted with permission from ref. [37]. Copyright© 2022 Elsevier.

Figure 8

Portable biosensor BOD analyzers. (a) Biosensor with a disposable receptor element based on P. fluorescens [40]. The size of the device, which has a built-in microcomputer, is 170 × 80 × 30 mm³. Reprinted with permission from ref. [40]. Copyright© 2022 Elsevier. (b) Biosensor based on a disposable microbial (S. cerevisiae) electrode chip (inner volume, 563 mL); the design included a micro-stirrer system [41]. Reprinted with permission from ref. [41]. Copyright© 2022 Royal Society of Chemistry. (c) Microsensor based on poly(neutral red) and P. aeruginosa bacteria modified interdigitated ultramicroelectrode array (IUDA) [42]. The volume of the measuring chamber was 1 mL; sensing area, 5 mm². Reprinted from ref. [42]. Copyright© 2022 Creative Commons Attribution 4.0 International License.

Figure 9

Schematic diagram of a sensor device. (a) Squint view of the sensor device. (b) Cross-sectional view from a gray arrow in the diagram of the squint view [21]. PET, polyethylene terephthalate. Reprinted with permission from ref. [21]. Copyright© 2022 Elsevier.

Figure 10

Mechanism of operation of a two-mediator system of potassium hexacyanoferrate (III)–menadione with S. cerevisiae cells [56]. Reprinted with permission from ref. [56]. Copyright© 2022 Elsevier.

Figure 11

Transfer of electrons to the electrode in a chitosan–neutral red redox polymer: (a) in the absence of carbon nanotubes; (b) in the presence of carbon nanotubes [57]. Reprinted with permission from ref. [57]. Copyright© 2022 Elsevier.

Figure 12

(a) Schematic design of a BOD biosensor chip; the components are (1) SO₃ glass slide, (2) Ru-complex dye–oxygen sensing film, (3) polyethylene–polypropylene film, (4) 0.5 mm thick silicone rubber sheet, (5) biofilm, (6) 1 mm thick silicone rubber sheet, (7) sample cavity or sample IN, (8) cover glass, (9) sample OUT [66]. Reprinted with permission from ref. [66]. Copyright© 2022 Elsevier. (b) Principle of the BOD_{chemiluminesc} method for BOD measurements. Not in stoichiometry [67]. Reprinted with permission from ref. [67]. Copyright© 2022 Elsevier.

Figure 13

Schematic of an MFC-based BOD biosensor [77]. Reprinted with permission from ref. [77]. Copyright© 2022 Elsevier.

Figure 14

(A) Schematic representation of the iBOB biosensor inserted into an intermittently aerating tank. Reprinted from ref. [85]. Copyright© 2022 Creative Commons Attribution 4.0 International license. (B) Anodes of the iBOB biosensor before (a) and after (b) use. The anode completely covered with suspended solids, including hay feed, is shown [85].

Figure 15

Schematic representation of the biosensor and the principle of operation. 1, biosensor operates in uncontaminated freshwater under open-circuit conditions; 2, in the presence of urine, the sensor open-circuit voltage increases; 3, the energy management system (EMS) switches ON, resulting in the charging of the capacitor up to a threshold; the audio and visual alarm is activated by the capacitor when full, causing the latter to discharge. The system is able to repeatedly charge/discharge the capacitor [86]. Reprinted with permission from ref. [86]. Copyright© 2022 Elsevier.

Figure 16

Design of a BOD microsensor (A); the structure sketch and photo of UMEA (B); structure sketch and SEM images of Fe₃O₄-functionalized B. subtilis (C); design and photo of tetrafluoroethylene support (D); photo of the sensor setup (E) [89]. Reprinted from ref. [89]. Copyright© 2022 Creative Commons Attribution 4.0 International license.

Figure 17

SEM and confocal laser scanning microscopy (CLSM) images of rGO–PPy-B microbial biofilm. (a) Typical SEM image of the interior microstructure of rGO–PPy-B microbial biofilm; (b) the magnified SEM image of (a); CLSM images of rGO–PPy-B microbial biofilm collected at the surface (c) and 6 mm depth (d) [45]. Reprinted from ref. [45]. Copyright© 2022 Creative Commons Attribution 4.0 License.

Figure 18

Electron micrographs of (a) chitosan–ex-cryogel matrix BSA; (b) chitosan–BSA–ex-cryogel matrix-activated sludge; (c) chitosan–cryogel matrix BSA; (e) chitosan–BSA–cryogel matrix activated sludge [51]. Reprinted with permission from ref. [51]. Copyright© 2022 Elsevier.

Figure 19

Scanning electron micrographs of N-vinylpyrrolidone-modified PVA. (a) A modified PVA matrix after swelling in a buffer solution; (b) a modified PVA matrix with immobilized P. yeei bacteria after swelling in a buffer solution [96]. Reprinted from ref. [96]. Copyright© 2022 Creative Commons Attribution 4.0 International license.

Figure 20

Schematic diagram of the three-stage MFCs as BOD sensor and compliance of predicted BOD₅ values with five-day BOD test (BOD₅). y = x is shown as the “ideal” prediction [143]. Reprinted with permission from ref. [143]. Copyright© 2022 Royal Society of Chemistry.

Figure 21

Schematic diagram of a BioMonitor BOD analyzer (LAR, USA) [144]. (1) Process control, measurement results display, interface diagram of periphery analyzers; (2) the aerated mixture of activated sludge and sample is pumped through the four reactors. The O₂ sensor determines the oxygen consumed during decomposition; (3) the activated sludge is aerated and its respiration is determined (ASR).

Figure 22

The main models of commercially produced BOD biosensor analyzers (photos are presented on the manufacturers’ web pages).