DETERMINATION OF ANTAGONISTIC PROPERTIES AND BIOFILM FORMATION IN BACILLUS SPP. AND LACTOBACILLUS SPP.

Abstract

The aim of the work was the selection of cultures of Bacillus spp. and Lactobacillus spp. promising for use as probiotics. Samples of chicken droppings (250 samples) for research were collected in the period of 2020 from clinically healthy chickens (age 28-48 days). in poultry farms of various scales and methods of keeping poultry (large-scale industrial farms, farms and homestead farms) in Vinnytsia, Zhytomyr, Kyiv, Kharkiv, Cherkasy, and Chernihiv regions. According to the results of bacteriological studies, 94 cultures of the genus Bacillus (B. subtilis, B. licheniformis, B. cereus, B. megaterium, B. pumilus) and 56 isolates of the genus Lactobacillus (L. delbrueckii, L. Lactis, L. Reuteri, L. casei, L. brevis). In general, 32.1 % of the studied isolates of Lactobacillus spp. and 21.3% of isolates of Bacillus spp. were able to form high-density biofilms in vitro. The results of determining the antagonistic properties showed that 98.4% and 91.5% of isolates of the genus Lactobacillus and the genus Bacillus respectively showed medium and high antagonistic activity against 17 test strains of microorganisms. The obtained results regarding the ability of the studied isolates to form a biofilm, antagonistic action, resistance to the aggressive environment of the digestive tract (pH level, bile) became the basis for the selection of promising cultures of the genus Bacillus and Lactobacillus for the purpose of developing a preparation with probiotic action. Further research will be aimed at determining the resistance of selected isolates to antimicrobial drugs and, subsequently, determining the effectiveness of selected isolates as part of a complex probiotic in experiments on chickens with the aim of evaluating their immunocorrective and antioxidant effects, as well as preventing the development of intestinal infections as an alternative to the use of antimicrobials drugs.