Adaptation of the microflora of pig farms to the disinfectant “Sviteco PIP Multi” and the antagonistic activity of the probiotic bacilli contained in its composition

Adaptation of microbes to antibacterial drugs, including disinfectants, is a global problem that poses a significant threat to human and animal health. In many sectors of the national economy, biocontrol is widely used to manage the microbial environment. This method involves the use of beneficial microorganisms or their metabolites to regulate the composition and activity of the microbiota to suppress pathogens. The work aimed to determine the adaptive capacity of the microflora of pig housing to the disinfectant “Sviteco PIP Multi” and to establish the presence and level of antagonistic activity of probiotic bacilli, which are components of the product, against isolated field isolates of microorganisms. As a result of the conducted research, the minimum bactericidal concentration (MBC) of the disinfectants “Vulcan Max” and “Sviteco PIP Multi” for gram-negative and gram-positive rod-shaped and spherical and convoluted field isolates of microorganisms isolated from pig housing facilities was determined. It was found that the MBC of the “Vulcan Max” product for gram-negative rod-shaped isolates, such as E. coli, K. pneumoniae, C. freundii, P. mirabilis, P. aeruginosa was from 0.035 to 0.08 %, and for “Sviteco PIP Multi” – from 0.023 to 0.05 %. Gram-positive isolates such as C. perfringens, B. subtilis, and B. megaterium showed the highest resistance since the MBC of “Vulkan Max” for them reached 0.12–0.26 %, and “Sviteco PIP Multi” – 0.08–0.18 %. The studied field isolates demonstrated faster adaptation to the disinfectant “Vulkan Max” since, with its prolonged exposure, individual representatives' growth was already noted at 45 passages. At the same time, adding “Sviteco PIP Multi” to the medium gave growth to most microorganisms at 49–50 subcultures and significantly lower concentrations. The antagonistic properties of the probiotic components of “Sviteco PIP Multi”, such as B. subtilis and B. megatherium, corresponded to the average activity level against all the studied isolates. For rod-shaped gram-negative isolates, the zone of growth inhibition ranged from 14.2 to 20.6 mm, for gram-positive isolates – from 14.8 to 18 mm, and for spherical and tortuous isolates – from 14.2 to 23 mm. The highest antagonistic activity of B. subtilis was demonstrated against S. aureus and P. mirabilis, and B. megatherium – S. aureus and B. subtilis. Concerning rod-shaped gram-negative isolates, the highest antagonistic activity was shown by B. subtilis, while against gram-positive B. megatherium. The zone of growth inhibition of field isolates caused by the indicated probiotic bacilli ranged from 14.2 to 20.6 mm and from 14.8 to 18 mm, respectively. The antagonistic activity of the probiotic components of the disinfectant “Sviteco PIP Multi” against coccal and tortuous isolates did not differ significantly, and the conditioned dew retention zones ranged from 14.2 to 23 mm.