Microbial based biosensors

Veima, N. Singh, M. A disposable microbial based biosensor for quality control in milk. Biosens. Bioelectron., Sep. 2003,18(10), 1219-1224. 

The selection of appropriate microorganisms is a possible way to improve the correlation between BOD and BODj [16,53]. The prerequisite for the use of microorganisms for BOD-sensors is a wide substrate spectrum. Therefore several samples of activated sludge from different wastewater plants were investigated [ 13,14]. One problem with an activated sludge based biosensor is the variability of sensor response with time. These BOD-sensors with an undefined variety of microbial species revealed no reproducible results. For that reason, BOD-sensors were developed using various types of defined cultures of microorganisms (Table 1). 

Central Kagaku Corp. (Tokyo,Japan) Biosensor Redox, microbial-based electrode... 

A wide range of microorganisms have been used as biocatalysts. Bacteria dominate but cyanobacteria, microfungi, protozoa, and microalgae have all been successfully used in biosensors. Whilst living cells have many benefits as biocatalysts they also pose unique problems and these need to be successfully overcome before microbial-based sensors can become commercially successful. Six major benefits can be identified ... 

Unlike enzyme-based biosensors such responses are subject to interference from a large number of other compounds to which the microbial biocatalyst would respond. Determination of the concentration or presence of specific analytes in mixtures is therefore difficult, although several approaches to overcome this problem have been employed including careful biocatalyst selection biocatalyst conditioning or induction and the use of inhibitors to suppress unwanted systems. 

In comparison to enzyme-based biosensors, microbial biosensors show lower analyte selectivity, slightly slower response times, but often much better stability. Microbial biosensor determination of analytes such as amino acids, alcohol, and lactate show sensor stability over several days, whilst enzyme-based sensors may have operational lives of only 2-24 h. 

Stein, N.E., Hamelers, H.V.M., and Buisman, C.N.J. (2010) Stabilizing the baseline current of a microbial fuel cell-based biosensor through overpotential control under non-toxic conditions. Bioelectrochemistry, 78 (1), 87-91. 

During the last few years an alternative approach for organophosphates detection has been proposed (40, 41). It relays on the monitoring of the reaction of enzymatic hydrolysis of OPCs by a specific microbial enzyme, organophosphate hydrolase (OPH). OPH-based biosensors have been shown to be useful for direct detection of various OPCs (40-43), as well as for discrimination between different classes of... 

Kumlanghan A, Liu J, Thavarungkul P, Kanatharana P, Mattiasson B (2007) Microbial fuel cell-based biosensor for fast analysis of biodegradable oiganic matter. Biosens Bioelectron 22(12) 2939-2944. doi 10.1016/j.bios.2006.12.014... 

Peixoto L, Min B, Martins G, Brito AG, Kroff P, ParpotP, Angelidaki I, Nogueira R (2011) In situ microbial fuel cell-based biosensor for tnganie earbon. Bioelectrochem 81(2) 99-103. doi 10.1016/j.bioelechem.2011.02.002... 

A. Kumlanghan, J. Liu, P. Thavarungkul, P. Kanatharana and B. Mattiasson, Microbial fuel cell-based biosensor for fast analysis of biodegradable organic matter. Biosens. Bioelectron. 22, 2007,2939-2944. 

Z. Liu, J. Liu, S. Zhang, X.-H. Xing and Z. Su, Microbial fuel ceU based biosensor for in situ monitoring of anaerobic digestion process. Bioresource Technol. 102, 2011,10221-10229. 

N.E. Stein, H.V.M. Hamelers and C.N.J. Buisman, Influence of membrane type, current and potential on the response to chemical toxicants of a microbial fuel cell based biosensor. Sens. Actuators B 163,2012,1-7. 

Jia J., Tang M., Chen X., Qi L., Dong S., Co-immobilized microbial biosensor for BOD estimation based on sol-gel derived composite material, Biosens. Bioelectr. 2003 18 1023-1029. 

Some new developments are also proposed such as a system based on the use of electrochemically active bacteria in combination with a microbial fuel cell [34], giving good responses over 60 days, or a biosensor developed for fast... 

Currently, a large spectrum of microbial biosensors have been developed that enable the monitoring of pollutants by measuring light, fluorescence, colour or electric current and electrochemical signal [60]. A recent study [19] shows that whole-cell biosensors based on the detection of changes in gene... 

Biosensors based on microbial immobilization have also been used for food applications, e.g., the inexpensive and rapid high-throughput bacterial biosensor developed by Virolainen et al. for rapid detection of tetracyclines and their 4-epimer derivatives in poultry meat [188, 189]. 

For these reasons, microbial sensors are less suitable for the determination of individual analytes. However, some practical apphcations for biosensors based on enzymes or antibodies for the specific determination of environmentally relevant compounds can be expected soon [11]. Furthermore, in some cases defined specific metabolic pathways in microorganisms are used, leading to microbial sensors for more selective analysis for those environmental pollutants which cannot be measured by the use of simple enzyme reactions, e.g., aromatic compounds and heavy metals. In this context it is also important to mention the aspect of bio availability, a parameter which is included by the measuring procedure of microbial sensors as an integral effect. 

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