Determination of Pellet Formation of Streptomycetes from the Streptomyces albovinaceus Subclade

Abstract

Streptomycetes are an important group of biotechnological bacteria due to their ability to synthesize chemically different metabolites. Their hyphae, when cultivated in a liquid medium, form mycelial networks, from which large granules (pellets) are formed. It was established that the formation of pellets mostly negatively affects the efficiency of the industrial production of antibiotics and enzymes. The aim. To determine the presence of mat- and cslA/glxA/dtpA-clusters in genomes of streptomycetes from Streptomyces albovinaceus subclades and to investigate similarity of organizations of  analogous multigenic loci. Methods. Variant S. globisporus 1912-4Crt is a spontaneous mutant of strain S. globisporus 1912 (а wild type). The nucleotide sequence of its genomic DNA is included in the NCBI databases (accession number QWFA00000000.1, GenBank). Search for clusters in nucleotide sequences of streptomycetes was carried out using the BLASTN program package from the NCBI server. Loci of the mat- and cslA/glxA/dtpA-clusters of S. globisporus 1912-4Crt were used as queries. Results. It was established that one mat- and two cslA/glxA/dtpA-clusters are present in the genome of S. globisporus 1912-4Crt, which ensures pellet formation. The GenBank database contains information on the primary DNA structure of 13 strains, of which 11 strains belong to the species S. globisporus and by one strain - to the species S. mediolani and S. albovinaceus. BLASTN analysis established the presence in genomes of 9 (75%) strains from the subclade of mat-cluster sequences. Also, cslA/glxA/dtpA clusters were found in their genomes, which, as a rule, are present in 2 copies per chromosome (83.3%). Exceptions were strains S. globisporus NRRL B-2293 and S. globisporus QF2. No cslA/glxA/dtpA-cluster was detected in the determined sequence of S. globisporus NRRL B-2293, and only 1 cluster was detected in the sequence of S. globisporus QF2. The found cslA/glxA/dtpA clusters, as a rule (91.3%), are organized by the scheme of the cluster from contig QWFA01000144: they contain only 3 functional genes. An exception is the cluster of S. globisporus M1, which contains 2 additional genes, as well as the cslA/glxA/dtpA-cluster of S. globisporus 1912 on contig QWFA01000051. Thus, it is reasonable to expect the formation of pellets by the mycelium of the majority of studied strains: aggregation clusters were found in 84.6% of the members of the subclade. Conclusions. Differences in the presence of mat- and cslA/glxA/dtpA-clusters in genomes of S. albovinaceus subclade strains were revealed along with differences in the copy number and organization schemes of cslA/glxA/dtpA-clusters and differences in the primary structures and organization schemes of cslA/glxA/dtpA clusters in one genome.