摘要:Extracellular contractile injection systems (eCISs) are structurally similar to headless phages and are versatile nanomachines conserved among diverse classes of bacteria. Herein,
Streptomyces species, which comprise filamentous Gram-positive bacteria and are ubiquitous in soil, were shown to produce
Streptomyces phage tail-like particles (SLPs) from eCIS-related genes that are widely conserved among
Streptomyces species. In some
Streptomyces species, these eCIS-related genes are regulated by a key regulatory gene, which is essential for
Streptomyces life cycle and is involved in morphological differentiation and antibiotic production. Deletion mutants of
S. lividans of the eCIS-related genes appeared phenotypically normal in terms of morphological differentiation and antibiotic production, suggesting that SLPs are involved in other aspects of
Streptomyces life cycle. Using co-culture method, we found that colonies of SLP-deficient mutants of
S. lividans were more severely invaded by fungi, including
Saccharomyces cerevisiae and
Schizosaccharomyces pombe. In addition, microscopic and transcriptional analyses demonstrated that SLP expression was elevated upon co-culture with the fungi. In contrast, co-culture with
Bacillus subtilis markedly decreased SLP expression and increased antibiotic production. Our findings demonstrate that in
Streptomyces, eCIS-related genes affect microbial competition, and the patterns of SLP expression can differ depending on the competitor species.