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Blubac System for Determining Microbial Growth in Clinical BluBAC system for determining microbial growth in clinical microbiological diagnosis samples by combining photostimulation and turbidimetry Nardo Ramírez-Frómeta1, Carlos A Lamothe-Nuviola1, Elier Riverón-Rodríguez1, Carmen Y Moreno-Barrios1, Angel Regueiro-Gómez2, Carmelo J Felice3 FOCUS 1 Centro Nacional de Investigaciones Científicas, CNIC Ave. 25 y Calle 158, Playa, Apartado Postal 6412, La Habana, Código Postal 10600, Cuba 2 Centro de Bioingeniería, CEBIO, Instituto Superior Politécnico José Antonio Echeverría, ISPJAE La Habana, Cuba 3Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina [email protected] ABSTRACT An experimental Workstation was designed, named BluBAC, intended for the microbiological diagnosis in clinical samples, which integrates photostimulation in two zones of the visible light spectrum: red (625 to 644 nm) and blue (430 to 480 nm), together with turbidimetric determinations in biological samples. It allows the analysis of photostimulation on microbial growth. The workstation comprises optoelectronic components and a MSP430 family microcontroller, connected through a Usb port to a computer for processing and visualizing the output signals com- ing from the samples. The signals are obtained through a graphic control interface in Visual Studio. The influence of the stimulation parameters (wavelength, light intensity, frequency and intensity of stimulation) on the growth of Escherichia coli cells was studied in bacterial cell cultures in DKD medium. The combination of photostimulation with turbidimetric determinations facilitated microbial detection, with decreased lag time and a longer exponential growth phase, stimulating bacterial growth more than other methods previously reported. These results evidenced the potential advantages of the experimental workstation BluBAC over other clinical microbiological diagnostic systems available in the market. Keywords: photostimulation, turbidimetric method, clinical microbiological diagnosis, blue light, Escherichia coli, BluBAC Biotecnología Aplicada 2016;33:2401-5 RESUMEN Sistema BluBAC para la determinación del crecimiento microbiano en muestras para el diagnóstico clínico microbiológico mediante fotoestimulación y turbidimetría. Se diseñó la estación de trabajo experimental BluBAC para el diagnóstico microbiológico en muestras clínicas, que integra la fotoestimulación en dos zonas del espectro luminoso visible: rojo (630 nm) y azul (de 430 a 480 nm) y permite la medición de turbidez en las muestras biológicas. De esta forma se puede analizar la influencia de la fotoestimulación en el crecimiento microbiano. La misma está formada por dispositivos optoelectrónicos y un microcontrolador de la familia MSP430 conectado a un ordenador a través de un puerto USB, en el que se procesan y grafican las señales de salida de las muestras, dichas señales obtenidas a través de una interfaz de control en Visual Studio. Se estudió la influencia de los parámetros del estímulo aplicado (longitud de onda, intensidad luminosa, frecuencia de estimulación e intensidad del estímulo) sobre el crecimiento de células de Escherichia coli cultivada en medio DKD. Se observó que la combinación de la fotoestimulación con la determinación de turbidez facilita la detección microbiana con un tiempo de latencia menor y una fase exponencial de mayor duración, lo que permitió estimular el crecimiento del microorganismo mucho más que mediante otros métodos previamente reportados. Estos resultados evidenciaron las ventajas potenciales de la estación experimental BluBAC sobre otros sistemas disponibles comercialmente para el diagnóstico microbiológico en muestras clínicas. Palabras clave: fotoestimulación, método turbidimétrico, diagnóstico clínico microbiológico, luz azul, Escherichia coli, BluBAC Introduction Photostimulation is the process by which light is ab- to photostimulation effects at different wavelengths sorbed by cellular molecules and subsequently con- there are the synthesis of adenosine triphosphate verted into energy. When a cell is photostimulated, the (ATP) and the synthesis of growth factors, among molecules bearing conjugated double bonds absorb others [1]. light at a particular wavelength set by its chemical Hence, the resulting effects in cell function from composition and attained a higher energy state. Then, the increased synthesis of ATP, which is the main those energized and excited molecules transfer the cell energetic intermediary molecule, and also the excess energy to other nearby molecules, triggering increased production of reactive oxygen species 1. Karu T. Primary and secondary mech- anisms of action of visible to near-IR a series of biochemical processes. Among the meta- (ROS), initiate signal transduction cascades leading radiation on cells. J Photochem Photobiol bolic processes and biochemical reactions susceptible to the downstream expression of growth factors and B.1999;49(1):1-17. Ramírez-Frómeta, N et al. BluBAC workstation for photostimulation of E. coli ultimately to cell proliferation. Particularly, ROS af- generate the photostimulatory signal and the other for fect homeostasis parameters such as cellular pH which the reception and measure of the resulting signal. alters cell functions, calcium ion concentrations which The stimulation block generates a low level signal stimulate the different signaling pathways, including delivered from 5 LED lamps to the biological samples the activation of photoreceptors and also growth fac- to be analyzed. Each LED stimulates a single turbidi- tors production [2]. It is known that small changes in metric measuring well in the sample platen, adjusted ATP concentrations could significantly affect the cell to provide simultaneously the same stimulatory signal metabolism, since an increased energetic state could (Figure 1B). The signal is controlled attending to four improve the metabolic performance even in cells un- main parameters: wavelength, frequency, light inten- dergoing deleterious processes [3, 4]. sity (candela) and stimulus light intensity (current). Moreover, a series of experiments have demonstrat- The stimulation block generate stimulatory and also ed that ATP is not solely implied in a higher energetic reference signals, for what it includes a tension-cur- state but also for an increased signaling among cells in rent conversion unit (Howland’s generator) and two multicellular organisms [5]. Therefore, the photostim- AD9834 circuits to generate the respective stimula- ulation of ATP is fundamental to understand the ubiq- tory and reference signals for the demodulation pro- uitous effects of photoaception mechanisms [5, 6]. cess. This device is a low power (20 mW) direct digi- Seven types of photoaceptor proteins have been de- tal synthesizer (DDS) able to generate high quality scribed so far: rhodopsins; xantopsins; phytochromes; sinusoidal and triangular signals [12]. 2. Kushibiki T, Tajiri T, Ninomiya Y, Awazu cryptochormes; LOV-domain (light, oxygen and ten- The reception unit measures the intensity of the K. Chondrogenic mRNA expression in prechondrogenic cells after blue laser sion domain) carrying proteins; BLUF (blue light light signal passing through the sample by means of irradiation. J Photochem Photobiol B. utilizing flavine adenosine dinucleotide) domain pro- an opto-electronic integrated circuit OPT-301, which 2010;98(3):211-5. teins and the family of eight proteins resistant to ultra- includes a photodiode and a monolithic transimped- 3. Eells JT, Wong-Riley MT, VerHoeve J, violet light [7]. Of them, blue light, that is the one of ance amplifier. The output of the photodetector is con- Henry M, Buchman EV, Kane MP, et al. higher frequency for simulation, is perceived by cryp- nected to a synchronous demodulation unit (AD630), Mitochondrial signal introduction in ac- celerated wound and retinal healing by tochromes, LOV-domain and BLUF-domain proteins, which filters the signal and converts it with the aid near-infrared light therapy. Mitochondrion. which have been characterized in detail through bio- of a lock amplifier, synchronizing the signal for the 2004;4(5-6):559-67. chemical and biophysical methods from photon ab- subsequent demodulation process. The processing 4. Wong-Riley MT, Liang HL, Eells JT, sorption downstream the signal transduction cascades unit (minicontroller MSP430FG4618) generates an Chance B, Henry MM, Buchmann E, et to the final biological activities [8]. After the initial average value from readings to minimize the errors al. Photobiomodulation directly benefits primary neurons functionally inactivated photoexcitation event, intrinsic structural changes are derived from coupling interferences. by toxins: role of cytochrome c oxidase. J induced in photoreceptors, such as the formation of Turbidimetry was implemented based on light ab- Biol Chem. 2005;280(6):4761-71. double covalent linkage of the chromophore [9]. sorption as a function of the concentration of bacte- 5. Burnstock G. Purines and sensory nerves. There have been described methods to take ad- rial cells, in compliance with the Lambert-Beer’s law Handb Exp Pharmacol. 2009;194:332-92. vantage of the photostimulation processes described [13], according to the equation 1: above for microbial manipulation with varied purpos- 6. Khakh B, Burnstock G. The double life of I = I e -[aA + aB] x C [1] ATP. Sci Am. 2009;301(6):84-92. es. For instance, a method was patented to stimulate o the metabolism of non-phytotrophe microorganisms Where: 7. Masuda S. Light Detection and Signal Transduction
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