Modern studies using bioluminescent ATP sensing are interesting for the understanding of main trends and possibilities of using this highly sensitive analysis. In many cases it appeared that bioluminescent ATP-chemosensing is continued to be used for research in the fields of sanitation, biomedicine, toxicology, in solving environmental problems, developing and using environmental technologies, antimicrobials and food products, chemical and biological protective agents and anticorrosive agents, new and effective biocatalysts and biotechnological processes, cell storage facilities, and differentiated cell analysis.
2. Main Modern Trends in the Use of Bioluminescent ATP Determinations
An analysis of a fairly wide list of studies related to various fields of application of bioluminescent ATP analysis published over the past 5 years
[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] showed that in some cases, the basic needs for using this analytical method remained similar to those that developed and were popular in previous years
[1]. At the same time, the main areas of recent applications of bioluminescent ATP-metry include sanitary control, quality control of purified water, microbial analysis in the food industry, maintenance of drugs and estimation of medicines’ quality, and monitoring of the state of biocatalysts used in various biotechnological processes.
This method of analysis’s application to detect the presence of various microorganisms is interesting and diverse, and it should be noted in the field of sanitary control of various objects. Here, ATP sensing is used to analyze various surfaces in hospitals and places intended for short-term stay of patients
[10][11][15][16][20][21], surfaces of instruments used for examination and treatments of patients
[13][14][17][18], and also as tools and places for slicing and cooking of food products
[24][25], where sanitation is important for human health. The express analysis in real time and sensitivity of the bioluminescent determination of ATP, as well as the amount of total information obtained, make it possible to assess the degree of contamination by microbial cells from different points of examination, identify the main sites of cell pollutions and monitor the effectiveness of methods and reagents used for sanitary treatment. Comparing the method of bioluminescent ATP determination with microbiological methods of cell counting, the authors often note the effectiveness of the first approach
[19][23][37]. It should be noted here that in some cases, the comparison of the results of ATP-metry and classical methods of microbiology do not always coincide
[7][12] due to the fact that detergents and disinfectants used for sanitary treatment can partially inhibit the catalytic activity of luciferase, which forms the basis of the reagent used in bioluminescent ATP- assay. It appeared that residues of blood and urine present in samples from hospitals
[12] also can change the luciferase reaction. Further, special attention will be paid to this issue, since the chemicals that may be present in the analyzed samples and affect the activity of luciferase, as the practice of ongoing research shows, may be different.
In addition, bioluminescent ATP-assay is used as a tool for evaluating newly developed sterilization technologies
[22], since the high sensitivity of the method ensures the detection of even a small number of microbial cells
[2][40].
Assessment of water quality using ATP-metry methods proved to be required in a variety of areas, including assessment of the effectiveness of wastewater treatment, counting hospital origin
[12][38], the successful operation of seawater system used for simultaneous desalination and removal of microbial cells
[8], and ballast water treatment systems of ships
[39][41].
A special place in the studies of water samples using bioluminescent ATP-metry is occupied by experiments on the analysis of microalgae and plankton amounts, including Arctic water systems
[9][40]. The results of these studies allow people not only to predict the expected pollution of ballast water on ships, but also provide information of an ecological nature, namely, on the development of certain microalgae in the waters of the seas and, consequently, the existence of conditions or factors affecting the level of their reproduction (increase or decrease in the concentration of cells).
Interestingly, in some cases, this method allows one to establish extremely interesting facts. In particular, when using the marine diatom microalgae
Thalassiosira weissflogii cultivated under various conditions, it was found that the specific level of ATP per cell can remain relatively constant, despite changes in cell growth rates in the periodic cultivation regime by about 10 times
[40].
It is also interesting that this method of bioluminescent ATP-assay has been modified to detect plankton, which in addition to microorganisms, includes larger inhabitants of marine waters (≥50 microns)
[39]. Modification of sample preparation for the application of the analytical method consisted in additional grinding of all sample components.
The use of bioluminescent ATP-assay in processes directly related to the study of the activity of microorganisms makes it very easy and efficient to assess the metabolic state of cells and react as quickly as possible in case of such a need
[45][46][47][48][49]. It does not matter in which environment these cells are located. It is relevant to use the discussed method in collections of microorganisms to control the physiological state of a wide variety of cells
[43][55].
It is likely that the use of bioluminescent analysis of ATP may prove promising in experiments aimed at searching for living organisms in space. In particular, the soil from Mars did not show a negative effect on the activity of luciferase in determining its artificial contamination by
E.coli cells
[51].
It is attractive to use the bioluminescent ATP-assay method in the development of new antimicrobial drugs, including those based on the combination of antibiotics or antimicrobial polypeptides with enzymes that are capable of quenching the quorum of various microorganisms (Gram-positive, Gram-negative bacterial cells, and yeast)
[27][56][57][58][59]. In practical terms, the use of bioluminescent ATP-assay in the development of new porous materials with the functions of protection from the effects of chemical (organophosphorus neurotoxins, and mycotoxins) and biological agents (bacterial cells) seems to be a new and promising direction of the analytical method development.
The results obtained with ATP-metry are valuable for the subsequent development of the functional fibrous materials, since isolation of remaining living cells of microorganisms from tissue materials with detoxifying and decontaminating protective properties for further their analyzing by traditional microbiological methods is extremely difficult, whereas ATP extraction is possible and convenient
[45][46][47][48][49]. In addition, the dependence of the residual concentration of intracellular ATP in some samples on the concentration of an antimicrobial drug used for treatment of cells makes it possible to establish the minimum inhibitory concentration of the substance or the resistance of microorganisms to this substance
[28][29][34].
Determination of the resistance of some surfaces or coating materials to microbial contamination by using bioluminescent ATP-assay is also relevant in the development of new composite materials
[44], during restoration works
[50][52][53], and in the preservation of archaeological finds
[54]. When assessing the susceptibility of various historical monuments to microbial damage, the authors, using bioluminescent ATP sensing, try to conduct environmental monitoring, establishing a relationship between the outbreak of microorganisms and the relevant environmental factors
[52][53][54].
In general, it can be noted that the applications of bioluminescent ATP-metry can be very diverse and are expected to be associated not only with the presence/absence of microorganisms in some samples. In particular, studies with blood and liver cells seem to be quite voluminous in terms of the number of experiments conducted
[30][32][33][35][36]. That is also a very positive area of ATP-metry application developed recently based on fundamental interest in the role of ATP in relation to the development of diseases.
The main task of all these studies remains the necessary sampling, ensuring the completeness of ATP extraction from cells, and rational consideration of factors affecting the accuracy and sensitivity of the determination, in particular, consideration of the possible inhibitory effects of various substances on the main participant in the determination of ATP (luciferase).