ABSTRACT
The construction of the expression vector pLF22 for lactic acid bacteria is described. The vector contains a replicon of the cryptic plasmid pLF1311 from Lactobacillus fermentum and a multiple cloning site of the lacZ' gene integrated with the plasmid rep operon. Such a construction of the vector provides for the constitutive transcription of the cloned sequences lacking the terminators of transcription in all the strains that maintain the replication of the vector. The vector is suitable for a wide range of gram-positive and gram-negative bacteria, including probiotic strains. The efficiency of the vector was verified by expressing the beta-galactosidase gene in a laboratory Escherichia coli strain and the synthetic gene of somatotropin releasing factor (SRF) in the probiotic strains of lactobacilli and enterococci. A recombinant strain with the SRF gene included in the diet of laboratory animals exerted an effect on their physiological and anthropometric parameters and on the histological characteristics of animal tissues.
