Acoustic Sensor System to Detect Bacteria in an Aquatic Environment
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stic Sensor System to Detect Bacteria in an Aquatic Environment O. I. Guliya, b, *, B. D. Zaitsevc, O. A. Karavaevaa, A. K. M. Alsowaidid, O. S. Larionovab, and I. A. Borodinac aInstitute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov, 410049 Russia b
Saratov State Agrarian University, Saratov, 410012 Russia Kotelnikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Saratov Branch, Saratov, 410019 Russia d Chernyshevsky National Research State University, Saratov, 410005 Russia *e-mail: [email protected]
c
Received March 10, 2020; revised April 13, 2020; accepted April 22, 2020
Abstract—A method been developed for the rapid determination of bacteria on the example of E. coli cells in tap water with a slot-mode sensor in the acoustic-delay line. The method is based on the recording of changes in the depth and frequency of the resonance-absorption peaks on the frequency dependence of the output signal of the sensor before and after the infection of microbial cells with specific bacteriophages. Control experiments excluding the nonspecific interaction of microbial cells with bacteriophages were carried out. The bacterial detection limit turned out to be ~103 cells/mL with an analysis time of 5 min. A distinctive feature of the used sensor is the presence of a removable liquid container. This allows its reuse and facilitates the process of eliminating the sample from the container. Keywords: microbial cells, bacteriophages, detection and identification of cells, slot-acoustic mode, acousticdelay line, frequency dependence of total losses DOI: 10.1134/S0003683820050075
INTRODUCTION The study of microbial water pollution is an important task in the timely prevention of food poisoning and mass diseases. In biological (epidemic) terms, the safety of drinking water is determined by the complete absence of pathogenic bacteria, viruses, simple microorganisms, and helminth eggs, which cause infectious diseases in humans. Potable water must meet certain physical, chemical, and microbiological standards. The most common is the assessment of water safety by indirect bacteriological indicators: the degree of total bacterial contamination or the total microbial number, and the content of E. coli (Escherichia coli) The total microbial number is the number of microorganism cells in 1 mL of water that can form visible colonies after plating on solid nutrient media. According to existing standards, no more than 100 microbes (saprophytic aerobes and optional anaerobes) should be contained in 1 mL of drinking water. This is an indirect indicator of the bacterial contamination entering the water supply system. The E. coli content in water is determined by the coli index or coli titer. The index is the number of E. coli cells contained in 1 L of water, and the coli titer is the smallest volume of water in which 1 E. coli can be detected. The presence of E. coli is an indicator of fecal
contamination of water. The most reliable methods to determine bacteria
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