Dependence of biological activity of surfactants synthesized by Rhodococcus erythropolis IMV Ac-5017 on physiological state of yeast inducer

Introduction.Surfactants synthesized by Rhodococcus erythropolis IMV Ac-5017 can be used as antibiofilm agents due to their antimicrobial activity.The antimicrobial activity of surfactants can be increased by adding inducers to the R. erythropolis cultivation medium.Materials and methods.R. erythropolis IMV Ac-5017 was cultivated in ethanol-containing medium with Saccharomyces cerevisiae BTM-1 as an inducer.Surfactant concentrations were determined gravimetrically.The minimum inhibitory concentration was used to assess the antimicrobial activity of surfactants, and their ability to disrupt biofilms was determined by the spectrophotometric method.Results and discussion.The antimicrobial activity of surfactants synthesized by R. erythropolis IMB Ac-5017 and their ability to destroy biofilms can be significantly increased by introduction of S. cerevisiae BTM-1 cells being at different physiological states into the medium for cultivation.The surfactants synthesized by R. erythropolis IMV Ac-5017 in the presence of live S. cerevisiae BTM-1 cells, as well as the corresponded supernatant, exhibited the highest biological activity.Under these conditions, surfactants synthesized demonstrated the minimum inhibitory concentrations, which were 3.6-240 times lower compared to the values reported for surfactants produced in the medium without an inducer.Surfactants synthesized in the presence of inducers destroyed single-and dual-species biofilms by 9-59% and 1-29% more effectively, respectively, than those obtained in the medium without them.Surfactants of R. erythropolis IMV Ac-5017 obtained with inactivated inducer cells were less active, probably because proteins of inducer cells could be denatured during autoclaving.Biological activity of the surfactants produced in the presence of the yeast inducer was more specific towards yeast test cultures, which can be explained by the nature of the studied inducer.Conclusion.The addition of the yeast inducer into the medium for cultivation of R. erythropolis IMV Ac-5017 contributed to significant increase of biological activity of surfactants compared to those synthesized in the medium without an inducer.