An antimicrobial thiopeptide producing novel actinomycetes Streptomyces terrae sp. nov., isolated from subsurface soil of arable land

Abstract

An antimicr obial pr oducing Gram-positi v e, aer obic, nonmotile, and filamentous actinobacterial strain SKN60 T was isolated from soil The isolate exhibited 99.3% and 99.0% identity with Str eptom yces laur entii ATCC 31255 T and S . r oseicoloratus TRM 44457 T , r especti v el y, in 16S rRNA gene sequence anal ysis . Howev er, the genome sequence displayed maximum ANI (88.45%) and AAI (85.61%) with S. roseicol- oratus TRM 44457 T . Similarly, the dDDH showed 33.7% identity with S. roseicoloratus TRM 44457 T . It formed a cluster with S. roseicoloratus TRM 44457 T and S . laur entii ATCC 31255 T in phylogenomic tree . Cell wall analysis revealed the presence of diphosphatidylglycerol, phosphatid ylethanolamine, and phosphatid ylcholine as major polar lipids and diaminopimelic acid as diagnostic diamino acid. Ma- jor fatty acids were iso-C 15:0 , anteiso-C 15:0 , and iso-C 16:0 . The G + C content was found to be 72.3 mol%. Genome sequence analysis using antiSMASH database showed occurrence of a thiopeptide biosynthesis gene cluster with 94% similarity to berninamycin from S. bernensis UC5144. The mass of 1146 Da is identical with berninamycin. But subtle differences observed in leader peptide sequence of thiope ptide and berninamycin. Nota b l y, S. bernensis is not v alidl y r e ported and thus SKN60 T is the only strain containing berninamycin BGC as no other phylogenetic r elati v e had it. Additionally, strain SKN60 T differed in phenotypic and genetic c har acteristics with all phylogenetic r elati v es of the gen us Str eptom yces . Ther efor e, it is pr oposed as a nov el species with the name Str eptom yces terrae sp . no v. strain SKN60 T ( = MTCC 13163 T ; = JCM 35768 T ).