The lack of lysine in the diet of pigs negatively affects appetite, weight gain, metabolism and immunity of animals. Most feeds for pigs are deficient in lysine. Synthetic amino acids, as feed additives, make feeds significantly more expensive. In this regards, the biologcs based on microbial producers able to synthetize lysine in the gastrointestinal tract of animals are promising. However, common producers of lysine, Brevibacterium lactofermentum, Escherichia coli and the genus Corynebacterium, are conditionally pathogenic as a causal agents of opportunistic infections. In the present study, we first examined the changes in intestinal bacterial community and the productive performance in Large White pigs («Novgorod bacon», Novgorod Province) under the influence a lysine producing strain Lactobacillus plantarum L-211 (JSC «Bioreactor», Moscow). Taxonomic composition of microorganisms was determined by T-RFLP (terminal restriction fragment length polymorphism) analysis. For surveillance we used two groups of pigs from 28-to 84-day age, fed with the basic diet (n = 715, group 1, control) and the same diet supplemented with L. plantarum L-211 at the dose not less than 10 9 CFU per animal added to water (n = 657, group 2). Microbial community in the pigs' large intestine was taxonomically divers and included a number of unidentified phylotypes. Here, the predominating bacteria were representatives of the phylum Firmicutes, including mainly Clostridia possessing cellulolytic and amylolytic properties, as well as the members of order Negativicutes able to ferment acids. The phyla Proteobacteria, Bacteroidetes, Actinobacteria and Fusobacteria were less abundant. The counts of genus Lactobacillus was lower than previously assumed, moreover, there was a complete absence of enterococci and bifidobacteria, which are usually attributed to the autochthonous microbiota of the large intestine of animals and birds. Lysine synthesizing strain L. plantarum L-211 had a high probiotic effect resulting in a significant increase in the counts of genera Lactobacillus (2.94-fold, P < 0.01) and Bacillus (3.29fold, P < 0.01), of phylum Bacteroidetes (5.29-fold, P < 0.01), and class Clostridia (2.05-fold, P < 0.01), whereas the proportions of pathogens from Staphylococcus genus and Сampylobacteriaceae family were below the T-RFLP sensitivity, and the family Pasteurellaceae decreased in number 1.41-fold (P < 0.05). Both the survival and the average daily weight gain (P < 0.05) in pigs, as influenced by the probiotic strain L. plantarum L-211, were higher. L. plantarum L-211 also improved feed conversion efficiency as compared to the control pigs.
