Оценка жизнеспособности бактериальных клеток при их взаимодействии с бактериофагами с помощью акустического датчика

Abstract

В статье представлен датчик на основе щелевой моды в акустической линии задержки для экспресс-анализа и оценки жизнеспособности бактериальных клеток непосредственно в жидкой проводящей суспензии. В качестве аналитического сигнала использовали изменение глубины и частоты пиков резонансного поглощения на частотной зависимости полных потерь выходного сигнала датчика до и после биологического взаимодействия бактериальных клеток с бактериофагами. Измерения проводились в суспензиях с начальной проводимостью 5–30 мкСм/см. Для подавления биохимических процессов в бактериальных клетках с целью оценки их жизнеспособности клеточную суспензию подвергали температурному воздействию в температурном интервале 60–100 °С с последующим охлаждением. Конструкция датчика позволяла многократно использовать съемный контейнер, при этом значительно упрощался процесс его очистки от отработанного образца.

The article presents a slot-mode sensor in acoustic delay line for rapid analysis and assessment of the viability of bacterial cells directly in a liquid conductive suspension. The main element of the sensor is the delay line made of the Y-X lithium niobate plate. Two interdigital transducers (IDTs) were applied to the surface of the plate to excite and receive the acoustic SH0 wave. A liquid container was placed above the waveguide of the delay line between the IDTs with the given gap of 8 μm. The bottom of the container was made of the Z-X + 30° lithium niobate plate. The sensor was connected to the Sparameter meter E5071C (Agilent, USA), and the frequency dependence of the insertion loss of the sensor output signal was measured. During the measurements the presence of pronounced resonance peaks in the frequency dependence of the insertion loss of the sensor associated with the excitation of the slot mode was observed. The method of the analysis of the microbial cells was based on recording changes in the depth and frequency of resonance absorption peaks on the frequency dependence of the insertion loss of the sensor before and after the biological interaction of the microbial cells with the specific bacteriophages. The sensor recorded the infection of microbial cells with the specific bacteriophages in suspensions with the initial conductivity of 4.5–30 μS/cm. The analysis time was 5–10 minutes, the limit of the determination of the microbial cells was 103 cells/ml. The control experiments were conducted with the nonspecific interactions of the microbial cells with the bacteriophages, in which no change in the sensor parameters was observed. To suppress the biochemical processes in the cells or the further assessment of their viability, the cell suspension was heated to 60, 80, and 100 °C. Then the cell suspension was cooled to the room temperature, placed in the liquid container and the sensor readings were recorded. After that, the specific bacteriophage was added and the sensor readings were again recorded. A distinctive feature of the used sensor is the lack of contact of the suspension under investigation with the thin (200 μm) waveguide of the delay line. Therefore, the additional advantage of the sensor is the presence of a removable container with the liquid, which allows to reuse it and to facilitate the process of cleaning the container from the spent sample. This fact is an important condition when working with microorganisms.