Estudo da cinética de crescimento e resistência de microrganismos (Saccharomyces cerevisiae e Zymomonas mobilis) na presença de cisplatina empregando um sistema fluxo-batelada

Abstract

This work utilized a flow-batch based system aiming to study the growth kinetic profile and resistance of microorganisms tested with inorganic drug cisplatin (CDDP), commonly used in cancer treatment. Aiming to reduce costs and waste production during the tests, Solenoid mini-pumps were used as fluid propulsion system. Such a device was connected to an integrated circuit ULN 2803 which was coupled to an electronic serial interface (USB 4000) to connect to computer's USB output that had the function to control the pulses of solenoid mini-pumps sent to reaction chamber. A multichannel UV-Vis spectrophotometer with a linear array of photodetectors was used as detection system. The data acquisition and control devices were obtained from program written in LABVIEW 8.5 language. Initially, the tests with Saccharomyces cerevisiae yeast were carried out to obtain their growth kinetic profile; however, the micro-organism produced a high amount of biomass and this caused interference in turbidimetric analysis, causing what we call backscattering or backscatter effect. In order to reduce interference, subsequent tests were performed with the bacterium Zymomonas mobilis, which not only produces a smaller amount of biomass but is also a non-pathogen used in cell biology. For such bacteria, it was was possible to obtain the kinetic growth profile and verify its behavior with the use of inorganic drugs cisplatin for a period of 24 hours. After this time the system presented interference and reading errors caused by the increase in cell concentration. To evaluate the CDDP-resistance profile of the Z. mobilis turbidimetric readings were performed at 600 nm in UV-Vis without the flow-batch system. The cell count of the microbial were carried out in a Neubauer chamber and Gram stain was checked on glass slides. The result from such analyzes, reaffirm the anti-mitotic action of cisplatin as well allowed the chronological elucidation of the biochemical mechanisms of the resistance against anticancer tested (CDDP).