Microbial piggy-back: how Streptomyces spores are transported by motile soil bacteria

Abstract

Streptomycetes are sessile, soil-dwelling bacteria that produce diverse metabolites that impact plant health and the behavior of microbial communities. Emerging studies have demonstrated that Streptomyces spores are distributed through a variety of mechanisms, but it remains unclear how spores are transported to their preferred micro-environments, such as plant roots. Here, we show that Streptomyces spores are capable of utilizing the motility machinery of other soil bacteria and are transported on the centimeter scale. Motility assays and microscopy studies reveal that Streptomyces spores are transported to plant tissues by interacting directly with the flagella of both gram-positive and gram-negative bacteria. Genetics experiments demonstrate that this form of motility, called piggy-backing, is facilitated by conserved structural proteins present on the surface of Streptomyces spores. These results demonstrate that non-motile bacteria are capable of utilizing the motility machinery of other microbes to complete necessary stages of their lifecycle, and that this mode of transport may be ubiquitous in nature.