Biofilms Pseudomonas Aeruginosaand the Prospects for Decontamination of Reservoirs of a Closed Water Purification System

Abstract

Objective: study of morphometric and densitometric parameters of biofilms bacteria Pseudomonas aeruginosa under the influence of a disinfectant.

Materials and methods: Bacteria Pseudomonas aeruginosa were cultivated at 37o C, 48 h - control; under the influence of various concentrations of the disinfectant "Abacteril" (LLC "Rudez", Russia) - experience. For morphometric and densitometric indices, 18-hour cultures of microorganisms, 105 CFU / ml were cultivated on coverslips placed in the wells of a microplate. For the detection of non-cultured microorganisms, we used media containing components for cell wall repair and L-form reversal. To obtain representative information, optical microscopy was performed by random selection of the field of view of a microscope model "BIOMED MS-1 Stereo" (Russia). The optical density (Optical Density - OD) of biofilms was determined by the degree of binding of crystal violet (Himedia, India) at a wavelength of 490 nm in anmicroplate photometric analyzer Immunochem-2100 (HTI, USA).

Results: The inhibitory effect of various concentrations of the disinfectant was expressed by the destruction of the extracellular matrix and a significant decrease in the frequency of occurrence of microcolonies and the frequency of occurrence of clusters - aggregation of microorganisms united by a layer of the extracellular matrix. When exposed to a 0,25 % solution of the drug, the optical density indicators significantly decreased: ODs – 0,374 ± 0,09, the intensity of formation - ID ≥ 0,2-0,3, respectively, pseudomonas - moderate producers of biofilms. The study of the effect of 0,50 and 0,75 % concentrations of the drug revealed a more intense effect on the processes of formation of the extracellular matrix. Thus, the decrease in optical density indices was ODs – 0,199 ± 0,09 – 0,245 ± 0,09, the intensity of biofilm formation - ID ≥ 0,1–0,2,  accordingly, pseudomonads are weak producers of biofilms. For the detection of non-cultured microorganisms, we used media containing components for cell wall repair and L-form reversal.

Conclusion: Under the influence of various concentrations of the disinfectant, a correlation dependence (r = 0,93) of a significant decrease in morphometric and densitometric parameters of biofilms was established. The regularities of a decrease in the degree of formation of the extracellular matrix and the frequency of occurrence of clusters - the aggregation of microorganisms united by a layer of the extracellular matrix - have been established.