Chromosomal localization patterns of beta-galactosidase genes in streptomycetes

Aim. The aim is to identify trends of localization of genes encoding beta-galactosidase (β-gal genes) in the genomes of streptomycetes. Methods. Genetic maps of 94 strains of streptomycetes from the NCBI server database were analyzed. Results. Molecular sizes of genomes from the strains sample were from 6.84 Mbp up to 12.7 Mbp. Most of genomes (43.7 %) in the sample have molecular sizes 7.0 Mbp – 8.5 Mbp. As determined, the number of β-gal genes on genetic maps ranged from 0 to 13. 61.3 % of the strains contained 1 - 3 β-gal genes in their genomes. It has been established that these genes are located in the genomes of streptomycetes, as a rule, in terminal regions. 79 % of the studied β-gal genes had a molecular size from 1.5 kb. up to 2.1 kb. Conclusions. The following patterns of localization of β-gal genes in the genomes of streptomycetes were established: 1) Tendency of localization of the overwhelming majority of β-gal genes in the terminal regions of streptomycete genomes; 2) Trend has been established for the localization in the core region of individual β-gal genes, both in genomes of large molecular size and containing more than 8 genes; 3) The streptomycetes genomes contain the β-gal genes mainly of the size from 1.5 kb up to 2.1 kb regardless of molecular sizes of their genomes and the number of β-gal genes in them. Keywords: β-gal gene, genome, Streptomyces, molecular size.