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Документ Destruction of biofilms under the influence of Acinetobacter calcoaceticus IMV B-7241 surfactants, synthesized in the presence of competitive microorganisms(2022) Pirog, Tatiana; Ivanov, MykytaIntroduction. The aim of this study was to investigate the role of surfactants synthesized by Acinetobacter calcoaceticus IMV B-7241 in media with glycerol in the presence of biological inductors in destruction of biofilms. Materials and methods. Cultivation of A. calcoaceticus IMV B-7241 was carried out in a mineral medium using refined glycerol or crude glycerol, the waste of biodiesel production, as carbon sources. Biological inductors were introduced as live or inactivated cells of Bacillus subtilis BT-2, as well as the supernatant after strain BT-2 cultivation. Surfactants were extracted from the supernatant of the culture liquid with a modified mixture of Folch (chloroform and methanol, 2:1). The degree of biofilm destruction in the presence of surfactants was determined by spectrophotometric method. Results and discussion. Regardless of the substrate used, the introduction of both live and inactivated cells of B. subtilis BT-2 into medium used for cultivation of A. calcoaceticus IMV B-7241 was accompanied by the synthesis of surfactants, the degree of biofilm destruction of which was higher than those obtained in the medium without an inductor. The degree of destruction of bacterial and yeast biofilms achieved by the action of A. calcoaceticus IMV B-7241 surfactants obtained on refined glycerol in the presence of inductor cells was 36.5–85% and was 1.5-3 times higher compared to using surfactants synthesized in medium without inductors. Note that, surfactants synthesized in the presence of biological inductors destroyed biofilms of the test cultures at fairly low (7.5–960 μg/ml) concentrations. Similar results were observed for the usage of surfactants obtained on the waste of biodiesel production. Therefore, introduction of live cells of B. subtilis BT-2 into the medium with the crude glycerol was accompanied by synthesis of surfactants, which at concentration 1.8-960 μg/ml caused destruction of B. subtilis BT-2, Proteus vulgaris PA-12 and Enterobacter cloacae C-8 biofilms at 30.1–80.7% and was higher than using similar surfactant concentrations obtained during cultivation without inductors (24.1–75%). The destruction of biofilms of Staphylococcus aureus BMS-1, Candida albicans D-6 and Candida tropicalis PE-2 under the action of surfactants (1.8-960 μg/ml) synthesized on crude glycerol in the presence of both live or inactivated cells of B. subtilis BT-2 was 1.5–8 times higher than surfactants synthesized in medium without inductor. Conclusion. The possibility to regulate the ability to destroy bacterial and yeast biofilms of surfactants synthesized by A. calcoaceticus IMV B-7241 by introducing into the medium competitive bacteria B. subtilis BT-2 was found.Документ Regulation of biological activity of surfactants under cultivation of Acinetobacter calcoaceticus IMB B-7241 on glycerol(2021) Pirog, Tatiana; Lutsay, Dariya; Yarova, HannaIntroduction. The aim of this research was to study the biological activity of surfactants synthesized by Acinetobacter calcoaceticus IMV B-7241 in the medium with glycerol of various degrees of purification and high content of calcium cations (activators of NADH+-dependent glutamate dehydrogenase, which is a key enzyme of biosynthesis of surface-active aminolipids responsible for antimicrobial activity of surfactant complex). Materials and methods. Cultivation of A. calcoaceticus was carried out in liquid mineral medium using as substrates refined glycerol and the waste from biodiesel production. The base medium did not contain calcium chloride, the content of CaCl2 in the modified medium was 0.1 and 0.2 g/l. Surfactants were extracted from the supernatant of the culture luquid with a modified mixture of Folch. The number of adhered cells and the degree of biofilm destruction in the presence of surfactants was determined by spectrophotometric method, antimicrobial activity of surfactants - by the minimum inhibitory concentration (MIC). Results and discussion. It was found that the additional introduction of 0.1−0.2 g/l of CaCl2 into cultivation medium with refined glycerol was accompanied by the synthesis of surfactants, the MIC of which against bacteria (Bacillus subtilis BТ-2, Enterobacter cloacae C-8, Staphylococcus aureus BМS-1) and yeast (Candida albicans D-6) were 1.01–21.3 μg/ml and were 1.4–29 times lower compared to the MIC of surfactants obtained in base medium (1.83−58.8 μg/ml). The adhesion of test cultures on abiotic materials treated with such surfactants was 8–13% lower, and the degree of biofilms destruction was 5–19% higher compared to the values, established for surfactants obtained on base medium. The increasіng antimicrobial and anti-adhesive activity of surfactants synthesized on waste of biodiesel production was observed only when CaCl2 was introduced into the medium at a concentration of 0.2 g/l. Surfactants synthesized in the presence of calcium cations in the medium with the waste of biodiesel production proved to be more effective destructors of bacterial biofilms in comparison with those obtained in the base medium only at low concentrations (0.7–5.5 μg/ml). Conclusion. The results demonstrate the possibility of regulating the biological activity of A. calcoaceticus IMV B-7241 surfactants by changing in the composition of medium content of calcium cations - activators of NADH+-dependent glutamate dehydrogenase (key enzyme of surface-active aminolipids biosynthesis). Surfactants synthesized under different cultivation conditions of A. calcoaceticus IMB B-7241 on glycerol are more effective biofilm destructors and antimicrobial and anti-adhesive agents compared to the known lipopeptides and rhamnolipids formed on glycerol.