Microbial Biosensor Research Articles

Microbial biosensors for diagnostics, surveillance and epidemiology: Today's achievements and tomorrow's prospects.

Microbial biosensors hold great promise for engineering high-performance, field-deployable and affordable detection devices for medical and environmental applications. This review explores recent advances in the field, highlighting new sensing strategies and modalities for whole-cell biosensors as well as the remarkable expansion of microbial cell-free systems. We also discuss improvements in robustness that have enhanced the ability of biosensors to withstand the challenging conditions found in biological samples. However, limitations remain in expanding the detection repertoire, particularly for proteins. We anticipate that the AI-powered revolution in protein design will streamline the engineering of custom-made sensing modules and unlock the full potential of microbial biosensors.

A NOVEL GOLD NANOPARTICLE‐IONIC LIQUID NANOSTRUCTURE MODIFIED Pleurotus Ostreatus BASED MICROBIAL BIOSENSOR SYSTEM FOR BISPHENOL A

The current study develops the first and novel gold nanoparticle‐ionic liquid nanostructure modified microbial biosensor based on <i>Pleurotus ostreatus</i> for the sensitive determination of Bisphenol A <b>. </b>In the construction of the microbial biosensor, lyophilized <i>P.ostreatus</i> cells were modified with ionic liquid‐cysteamine mixture on a gold electrode which was modified with 1,6‐hexanedithiol and gold nanoparticle. The measurement principle of the biosensor is based on the detection of changes in current in a phosphate buffer system (pH 7.5, 50 mM and containing 5.0 mM K <sub>3</sub>[Fe(CN) <sub>6</sub>]) in the potential range of ‐0.2 to +0.6 V depending o

Rapid, Sensitive, and Specific Microbial Whole-Cell Biosensor for the Detection of Histamine: A Potential Food Toxin.

Histamine is a biogenic amine; its level indicates food quality, as elevated levels cause food poisoning. Therefore, monitoring food at each step during processing until it reaches the consumer is crucial, but current techniques are complicated and time-consuming. Here, we designed a Pseudomonas putida whole-cell biosensor using a histamine-responsive genetic element expressing a fluorescent protein in the presence of the cognate target. We improved the performance of the proposed biosensor by optimizing the chassis, genetic regulatory element, and reporter gene. A sensitive and rapid biosensor variant was obtained with a limit of detection (LOD) of 0.39 ppm, manifesting a linear response (R2 = 0.98) from 0.28 to 18 ppm in 90 min. The biosensor showed minimal cross-reactivity with other biogenic amines and amino acids prevalent in food, making it highly specific. The biosensor effectively quantified histamine in spiked fish, prawn, and wine samples with a satisfactory recovery. Additionally, a colorimetric sensor variant PAlacZ was developed enabling histamine quantification in seafood via a smartphone application, with an LODgray of 0.23 ppm, exhibiting a linear response from 0 to 2.24 ppm. Overall, this study reports an efficient, specific, and highly sensitive biosensor with strong potential for the on-site detection of histamine, ensuring food safety.

Microbial fuel cell technology: Novelties for a clean future

The degree of civilization exhibited by a society is largely determined by its reliance on energy, and as traditional energy sources such as fossil fuels become scarcer, new technologies will be required to secure sustainable energy. Microbial fuel cell technology is one of the most creative ways to meet humanity's energy demands because it can generate electrical energy from carbon sources. The framework of the limitations limiting the dissemination of this technology has been used to explore in depth new designs and configurations that have been produced recently. Future developments and current applications of this technology in bioremediation investigations are explored. The use of microbial fuel cell technology as a microbial biosensor for the identification of environmental contaminants is particularly significant. However, for a clean and sustainable ecosystem, it is imperative to disclose the challenges associated with the future adoption of this technology.

Unveiling the dynamics of intraoperative contamination in total hip arthroplasty: the discrepancy between particulate and microbial contamination in surgical site infection risk

BackgroundSurgical site infection (SSI) is a major problem following total hip arthroplasty (THA). This study investigated the impact of a standard intraoperative routine where the surgical team wears full-body exhaust suits (space suits) within a laminar airflow (LAF)-ventilated operating room (OR) on environmental contamination. Our primary objective was to identify potential modifiable intraoperative factors that could be better controlled to minimize SSI risk.MethodsWe implemented an approach involving simultaneous and continuous air sampling throughout actual primary cementless THA procedures. This method concurrently monitored both airborne particle and microbial contamination levels from the time the patient entered the OR for surgery until extubation.ResultsAirborne particulate and microbial contamination significantly increased during the first and second patient repositionings (postural changes) when the surgical team was not wearing space suits. However, their concentration exhibited inconsistent changes during the core surgical procedures, between incision and suturing, when the surgeons wore space suits. The microbial biosensor detected zero median microbes from draping to suturing. In contrast, the particle counter indicated a significant level of airborne particles during head resection and cup press-fitting, suggesting these procedures might generate more non-viable particles.ConclusionsThis study identified a significant portion of airborne particles during the core surgical procedures as non-viable, suggesting that monitoring solely for particle counts might not suffice to estimate SSI risk. Our findings strongly support the use of space suits for surgeons to minimize intraoperative microbial contamination within LAF-ventilated ORs. Therefore, minimizing unnecessary traffic and movement of unsterile personnel is crucial. Additionally, since our data suggest increased contamination during patient repositioning, effectively controlling contamination during the first postural change plays a key role in maintaining low microbial contamination levels throughout the surgery. The use of sterile gowns during this initial maneuver might further reduce SSIs. Further research is warranted to investigate the impact of sterile attire on SSIs.

Advances in microbial whole-cell sensors for the detection of aromatic compounds

The inherent stability and recalcitrance of benzene ring structures render aromatic compounds a major ecological concern and a substantial risk to human health. Hence, developing a facile and efficacious detection technique for aromatic compounds is essential. As our comprehension of aromatic compound characteristics deepens, microbial cell-based biosensors have emerged as increasingly popular tools in the detection of aromatic compounds. This article introduces the operational principles of microbial whole-cell biosensors and elucidates the construction techniques and applications of electroactive biofilm-based microbial whole-cell sensors, transcription factor-based microbial whole-cell sensors, and degradation gene promoter-dependent microbial whole-cell sensors in the detection of aromatic compounds. In addition, we review the methodologies for improving the performance of microbial whole-cell sensors based on surface display, logic gate construction, genetic circuit modification, and quorum sensing signal amplification.

Screening methods for antibiotic residue detection in milk: Recent advances, challenges, and regulations

Antimicrobial residues in milk pose a significant risk to human health, prompting regulatory bodies to establish safety limits to protect consumers. While traditional screening methods have primarily targeted single analytes or classes, recent advancements in multiclass screening techniques offer more comprehensive and efficient monitoring. This review highlights these advancements and focuses on methods developed since 2010, such as microbial inhibition tests, immunoassays, biosensors and LC–MS‐based approaches. It also discusses the strengths and limitations of these techniques, as well as the challenges associated with analysing milk's complex matrix, emphasising the ongoing need for innovation in food safety practices.

Principles and challenges of whole cell microbial biosensors in the food industry.

Whole cell microbial biosensors (WCMB) are mostly genetically modified microorganisms used to detect target molecules as indicators of biological and chemical contaminants as well as in the identification of compounds of interest in the food industry. The specificity and sensitivity of these biosensors are achieved through the design of genetic circuits that make use of genetic sequences such as promoters, terminators, genes encoding regulatory proteins or reporter proteins, among others. Despite the advances of WCMBs for their application, significant challenges are faced, such as cell stability, regulatory restrictions, and the need to optimize response times so that they can be a competitive detection tool in the market. This review explores the technological progress, potential and limitations of WCMBs in the food industry, starting by reviewing the operating principles of biosensors. The importance of selecting appropriate chassis cells and the integration of recognition elements and transducers to maximize their effectiveness in the detection of contaminants and compounds of interest in the food industry is highlighted.

Impact of Air-Cathodes on Operational Stability of Single-Chamber Microbial Fuel Cell Biosensors for Wastewater Monitoring

The increasing global water pollution leads to the need for urgent development of rapid and accurate water quality monitoring methods. Microbial fuel cells (MFCs) have emerged as real-time biosensors for biochemical oxygen demand (BOD), but they grapple with several challenges, including issues related to reproducibility, operational stability, and cost-effectiveness. These challenges are substantially shaped by the selection of an appropriate air-breathing cathode. Previous studies indicated a critical influence of the cathode on both the enduring electrochemical performance of MFCs and the taxonomic diversity at the electroactive anode. However, the effect of different gas diffusion electrodes (GDE) on 3D-printed single-chamber MFCs for BOD biosensing application and its effect on the bioelectroactive anode was not investigated before. Our study focuses on comparing GDE cathode materials to enhance MFC performance for precise and rapid BOD analysis in wastewater. We examined for over 120 days two Pt-coated air-breathing cathodes with distinct carbonaceous gas diffusion layers (GDLs) and catalyst layers (CLs): cost-effective carbon paper (CP) with hand-coated CL and more expensive woven carbon cloth (CC) with CL pre-applied by the supplier. The results show significant differences in electrochemical characteristics and anodic biofilm composition between MFCs with CP and CC GDE cathodes. CP-MFCs exhibited lower sensitivity (16.6 C L mg−1 m−2) and a narrower dynamic range (25 to 600 mg L−1), attributed to biofouling-related degradation of the GDE. In contrast, CC-MFCs demonstrated superior performance with higher sensitivity (37.6 C L mg−1 m−2) and a broader dynamic range (25 to 800 mg L−1). In conclusion, our study underscores the pivotal role of cathode selection in 3D-printed MFC biosensors, influencing anodic biofilm enrichment time and overall BOD assessment performance. We recommend the use of cost-effective CP GDL with hand-coated CL for short-term MFC biosensor applications, while advocating for CC GDL supplied with CL as the preferred choice for long-term sensing implementations with enduring reliability.

Biosensors in environmental analysis of microplastics and heavy metal compounds – A review on current status and challenges

Biosensors (biological sensors) are a promising alternative to standard analytical techniques for testing and monitoring in the environment, among others, heavy metals. Biological materials that detect heavy metals include enzymes, bacteria, fungi, and plant and animal cells. The paper aimed to evaluate the possibilities of biosensor usage in environmental analysis, considering an easy and environmentally friendly analysis of individual compounds (e.g., heavy metals) or their mixtures in various samples directly in the environment, as well as continuous monitoring of these compounds. The work considers biosensors' characteristics, classification, and operation principles. Attention is paid to the possibility of using bioluminescent bacteria as biological material in a biosensor. Examples of the study of heavy metals using various biological sensors were given. It also indicates the possibility of using biosensors to determine microplastics by applying specific hormones (estrogens) receptor use and peptides as a solution or incorporating them into living microbial cells. Additionally, support was given to the use of biosensors to monitor plastics' degradation in the water environment using recombinant whole-cell microbial biosensors as detectors for plastic monomers such as acrylic acid monomers. The application of the biosensors highlighted in the paper is to shorten the time of toxicity studies by using new indicators or acceptors. However, several challenges must be overcome, such as cell viability and activity. A continuous water-monitoring system that can handle a severely toxic sample has yet to be developed in toxicity monitoring.

Microbial nanomaterials: Role in sustainable agricultural practices

The increased use of chemical fertilizers, pesticides, soil-based heavy metals to improve productivity in agriculture results into higher pollution level in agroecosystem. It has become a major issue on a global scale that seriously jeopardizes people’s health and welfare as well as affects society and overall economy. In view of this, there is an urgent need to detect pollutants in the agroecosystem so that remediation practices can be implemented in time. The evolution of more responsive, affordable and precise technology is needed to create nano-sensors or nanodevices that can be used to monitor agricultural pollution, and the processes involved in pollution control. Major focused ones are those that can detect pollutants at very low concentration levels, as well as point-to-point sensing, in situ, and uninterrupted monitoring devices that offer synchronized data. These sensors are readily available in the market for the detection of organic pollutants, gases, volatile organic molecules, heavy metal ions, hazardous metal ions, etc. but they consume a lot of power and lack sophisticated technologies for improved selectivity and sensitivity. Their precision, sensitivity, response speed and environmental stability under actual operating conditions can all be improved with the aid of nanotechnology. In this study an attempt was made to describe how microbial biosensors can be used to detect toxic materials in agroecosystems. Additionally, an application of nanomaterials as pesticides and antimicrobial agent has also been discussed.

Efficient Removal of Water Soluble Fraction of Diesel Oil by Biochar Sorption Supported by Microbiological Degradation

The contamination of the water bodies by diesel oil (DO) and its water-soluble fraction (WSF) represents one of the most challenging tasks in the management of polluted water streams. This paper contains data related to the synthesis and characteristics of the plum stone biochar material (PmS-B), which was made from waste plum stones (PmS), along with its possible application in the sorption of the WSF of DO from contaminated water. Techniques applied in sample characterisation and comparisons were: Elemental Organic Analysis (EOA), Scanning Electron Microscopy−Energy Dispersive X-ray Spectroscopy (SEM-EDX), Fourier Transform Infrared Spectroscopy (FTIR), pH (pHsus) and point of zero charge (pHpzc). In order to increase the overall efficiency of the removal process, sorption and bioremediation were subsequently combined. Firstly, PmS-B was used as a sorbent of WSF, and then the remaining solution was additionally treated with a specific consortium of microorganisms. After the first treatment phase, the initial concentration of diesel WSF was reduced by more than 90%, where most of the aromatic components of DO were removed by sorption. The sorption equilibrium results were best fitted by the Sips isotherm model, where the maximum sorption capacity was found to be 40.72 mg/g. The rest of the hydrocarbon components that remained in the solution were further subjected to the biodegradation process by a consortium of microorganisms. Microbial degradation lasted 19 days and reduced the total diesel WSF concentration to 0.46 mg/L. In order to confirm the non-toxicity of the water sample after this two-stage treatment, eco-toxicity tests based on a microbial biosensor (Aliivibrio fischeri) were applied, confirming the high efficiency of the proposed method.

A Review of Fabrication Techniques and Optimization Strategies for Microbial Biosensors

Challenges of stability and specificity associated with early generation sensors necessitate the fabrication and optimization of microbial biosensors. More so, the global biosensors market size currently valued at USD25.5 billion in 2021 is expected to grow at a compound annual growth rate (CAGR) of 7.5% to USD36.7 billion in 2026. Microbial biosensors are bioanalytical systems that integrate microorganisms with a physical transducer to generate signals, thus, aiding the identification of analytes. The biosensors are fabricated through a series of steps comprising microbe selection, immobilization onto a matrix, microfabrication, calibration, and validation. The transducers integrated microorganisms generate quantifiable signals, enabling real-time monitoring of a diversity of analytes within food samples. The optimization strategies are scrutinized, with a particular focus on the integration of sundry nanoparticles, such as magnetic, gold, and quantum-dot nanoparticles, which enhance sensor performance. Distinct advantages offered by microbial biosensors promise to revolutionize food quality assessment via cost-effectiveness, rapid sample testing, and the ability to provide access to real-time data. Literature have highlighted certain limitations including interference from complex matrices, instability of microorganisms, and microbial lifespan. In assessing their economic importance, a comparative analysis is presented against conventional food analytical methods like ELISA, PCR, and HPLC; thus, highlighting the unique strengths of microbial biosensors. The future perspectives focus on the potential of the technology in addressing the need for continuous monitoring challenges, and research for further improvements in the biocompatibility of fabrication processes and long-term reusability.

Droplet-based microfluidic platform for detecting agonistic peptides that are self-secreted by yeast expressing a G-protein-coupled receptor

BackgroundSingle-cell droplet microfluidics is an important platform for high-throughput analyses and screening because it provides an independent and compartmentalized microenvironment for reaction or cultivation by coencapsulating individual cells with various molecules in monodisperse microdroplets. In combination with microbial biosensors, this technology becomes a potent tool for the screening of mutant strains. In this study, we demonstrated that a genetically engineered yeast strain that can fluorescently sense agonist ligands via the heterologous expression of a human G-protein-coupled receptor (GPCR) and concurrently secrete candidate peptides is highly compatible with single-cell droplet microfluidic technology for the high-throughput screening of new agonistically active peptides.ResultsThe water-in-oil microdroplets were generated using a flow-focusing microfluidic chip to encapsulate engineered yeast cells coexpressing a human GPCR [i.e., angiotensin II receptor type 1 (AGTR1)] and a secretory agonistic peptide [i.e., angiotensin II (Ang II)]. The single yeast cells cultured in the droplets were then observed under a microscope and analyzed using image processing incorporating machine learning techniques. The AGTR1-mediated signal transduction elicited by the self-secreted Ang II peptide was successfully detected via the expression of a fluorescent reporter in single-cell yeast droplet cultures. The system could also distinguish Ang II analog peptides with different agonistic activities. Notably, we further demonstrated that the microenvironment of the single-cell droplet culture enabled the detection of rarely existing positive (Ang II-secreting) yeast cells in the model mixed cell library, whereas the conventional batch-culture environment using a shake flask failed to do so. Thus, our approach provided compartmentalized microculture environments, which can prevent the diffusion, dilution, and cross-contamination of peptides secreted from individual single yeast cells for the easy identification of GPCR agonists.ConclusionsWe established a droplet-based microfluidic platform that integrated an engineered yeast biosensor strain that concurrently expressed GPCR and self-secreted the agonistic peptides. This offers individually isolated microenvironments that allow the culture of single yeast cells secreting these peptides and gaging their signaling activities, for the high-throughput screening of agonistic peptides. Our platform base on yeast GPCR biosensors and droplet microfluidics will be widely applicable to metabolic engineering, environmental engineering, and drug discovery.

Label-Free Surface-Enhanced Raman Scattering-Based Microbial Whole-Cell Biosensor for Acute Toxicity Assessment in Water

Label-Free Surface-Enhanced Raman Scattering-Based Microbial Whole-Cell Biosensor for Acute Toxicity Assessment in Water

Long-duration environmental biosensing by recording analyte detection in DNA using recombinase memory.

Microbial biosensors that convert environmental information into real-time visual outputs are limited in their sensing abilities in complex environments, such as soil and wastewater, due to optical inaccessibility. Biosensors that could record transient exposure to analytes within a large time window for later retrieval represent a promising approach to solve the accessibility problem. Here, we test the performance of recombinase-memory biosensors that sense a sugar (arabinose) and a microbial communication molecule (3-oxo-C12-L-homoserine lactone) over 8 days (~70 generations) following analyte exposure. These biosensors sense the analyte and trigger the expression of a recombinase enzyme which flips a segment of DNA, creating a genetic memory, and initiates fluorescent protein expression. The initial designs failed over time due to unintended DNA flipping in the absence of the analyte and loss of the flipped state after exposure to the analyte. Biosensor performance was improved by decreasing recombinase expression, removing the fluorescent protein output, and using quantitative PCR to read out stored information. Application of memory biosensors in wastewater isolates achieved memory of analyte exposure in an uncharacterized Pseudomonas isolate. By returning these engineered isolates to their native environments, recombinase-memory systems are expected to enable longer duration and in situ investigation of microbial signaling, cross-feeding, community shifts, and gene transfer beyond the reach of traditional environmental biosensors.IMPORTANCEMicrobes mediate ecological processes over timescales that can far exceed the half-lives of transient metabolites and signals that drive their collective behaviors. We investigated strategies for engineering microbes to stably record their transient exposure to a chemical over many generations through DNA rearrangements. We identify genetic architectures that improve memory biosensor performance and characterize these in wastewater isolates. Memory biosensors are expected to be useful for monitoring cell-cell signals in biofilms, detecting transient exposure to chemical pollutants, and observing microbial cross-feeding through short-lived metabolites within cryptic methane, nitrogen, and sulfur cycling processes. They will also enable in situ studies of microbial responses to ephemeral environmental changes, or other ecological processes that are currently challenging to monitor non-destructively using real-time biosensors and analytical instruments.

Reduction of Losses and Wastage in Seafoods: The Role of Smart Tools and Biosensors Based on Artificial Intelligence

This paper reviews current knowledge on the role of smart tools and biosensors based on artificial intelligence in reducing seafood loss and wastage. This study shows that a variety of biosensors, categorised according to how they function, can be used to measure the quality of seafood. These include optical biosensors, enzyme-based biosensors, immunosensors, microbial biosensors, DNA-based biosensors, electrochemical biosensors, optical biosensors, tissue-based biosensors, and piezoelectric biosensors. Among these biosensors, optical biosensors, electrochemical biosensors, and mechanical biosensors are the most significant. Again, this study report that, for seafood traceability and management, a variety of smart solutions including blockchain technology, quick response (QR) codes, data analytics, digital twins, and radio frequency identification (RFID) tags can be utilised. Catch data, vessel tracking data, and data from the processing plant are some of the different data sources that can be utilised to trace seafood products. Artificial intelligence tools like neural networks, deep learning, machine learning, and others can be used to forecast and improve seafood quality. It is crucial to study the development of biosensors that can properly identify the earliest signs of seafood contamination or rotting.

Novel Conductive Polymer Composite PEDOT:PSS/Bovine Serum Albumin for Microbial Bioelectrochemical Devices.

A novel conductive composite based on PEDOT:PSS, BSA, and Nafion for effective immobilization of acetic acid bacteria on graphite electrodes as part of biosensors and microbial fuel cells has been proposed. It is shown that individual components in the composite do not have a significant negative effect on the catalytic activity of microorganisms during prolonged contact. The values of heterogeneous electron transport constants in the presence of two types of water-soluble mediators were calculated. The use of the composite as part of a microbial biosensor resulted in an electrode operating for more than 140 days. Additional modification of carbon electrodes with nanomaterial allowed to increase the sensitivity to glucose from 1.48 to 2.81 μA × mM-1 × cm-2 without affecting the affinity of bacterial enzyme complexes to the substrate. Cells in the presented composite, as part of a microbial fuel cell based on electrodes from thermally expanded graphite, retained the ability to generate electricity for more than 120 days using glucose solution as well as vegetable extract solutions as carbon sources. The obtained data expand the understanding of the composition of possible matrices for the immobilization of Gluconobacter bacteria and may be useful in the development of biosensors and biofuel cells.

POTENTIAL USES OF MICROBIAL BIOSENSOR FOR DETECTION OF POLYPHENOLIC COMPOUNDS

Microbial principle-based biosensor containing immobilized enzyme tyrosinase has been used for detection of polyphenols in tea solutions. The immobilized tyrosinase based biosensor could detect polyphenols in the concentration range 10-80 mmol L-1. Immobilization of the enzyme by the cross-linking method gave good stable response to polyphenols. The biosensor was tested in the polyphenols compounds determination in vegetables extract and the results were compared with the Folin–Ciocalteau traditional method and the biosensor showed suitability to the quantification of the total polyphenol in the tested samples. In order to enhance the sensitivity and stability of the measurements, the electrodes modified with designable molecules have been used in electrochemical determination of polyphenolic compounds. Although the majority of modified electrodes successfully determined the concentrations of polyphenolic compounds, the fabrication of the electrochemical sensor is still one of the challenging tasks for the researchers.

Genetic Engineering of Microorganisms with Electroactive Genes for the Fabrication of Electrochemical Microbial Biosensors.

By integrating electroactive genes into engineered sensing microorganisms, information about the object to be measured can be converted into the output of an electrical signal, omitting the process of converting the output of an electrical signal in conventional sensing strategies and simplifying the steps of biosensor development. By utilizing synthetic biology methods, we can not only create novel genetic circuits by using logic gate operations and integrating genes from other biological components, solving biosensing issues in living systems and enhancing sensor performance, but also convert various types of genetic circuits into electrical signals, broadening the application range of biosensors. Here, we describe an example of how to genetically engineer microorganisms with electroactive genes and the fabrication of an electrochemical microbial biosensor.