New Multistrain Bacterial Consortium for Feed Probiotics

Introduction. Multistrain probiotics often include biocompatible strains, which leads to suppression of microbial viability and, as a result, decreases their efficacy. Therefore, new probiotics should be based on well-matched strains with no antagonism. Study objects and methods. The research featured strains of lactic and propionic acid bacteria from the VNIIPBT collection. The method of direct co-cultivation on dense medium (drop technique) was used to assess the biocompatibility of lactic acid bacteria. Antagonism was detected visually based on signs of suppression after 24 and 48 h after the onset of incubation. Antagonism of the consortia was assessed by the Romanovich method. Results and discussion. The screening resulted in seven promising strains with the specific growth rate of 0.32–0.84 h–1 and the maximum population density ≤ 2.2 billion CFU/cm3. A set of experiments on the strain adaptation mechanisms revealed combinations of strains with the lowest antagonism and competition for the substrate. The research resulted in a four-component consortium of Lactobacillus plantarum 314/8, Lactobacillus helveticus R0052/6, Enterococcus faecium B-2240D, and Propionibacterium freudenreichii subsp. shermanii 103/27. The optimal ratio was the one where the cultures were present in equal proportions. The study also described the biosynthetic properties of the consortium and the ratio of the strains in its composition. The consortium demonstrated a balanced growth, good strain compatibility, and absence of antagonism. The cultivation mode was tested anaerobically on milk whey at 37°C for 24 h (strain ratio = 1:1:1:1). Conclusion. The new consortium proved suitable for industrial production of feed probiotics.