Streptomycesas symbionts: an emerging and widespread theme?

Abstract

Streptomyces bacteria are ubiquitous in soil, conferring the characteristic earthy smell, and they have an important ecological role in the turnover of organic material. More recently, a new picture has begun to emerge in which streptomycetes are not in all cases simply free-living soil bacteria but have also evolved to live in symbiosis with plants, fungi and animals. Furthermore, much of the chemical diversity of secondary metabolites produced by Streptomyces species has most likely evolved as a direct result of their interactions with other organisms. Here we review what is currently known about the role of streptomycetes as symbionts with fungi, plants and animals. These interactions can be parasitic, as is the case for scab-causing streptomycetes, which infect plants, and the Streptomyces species Streptomyces somaliensis and Streptomyces sudanensis that infect humans. However, in most cases they are beneficial and growth promoting, as is the case with many insects, plants and marine animals that use streptomycete-produced antibiotics to protect themselves against infection. This is an exciting and newly emerging field of research that will become increasingly important as the search for new antibiotics switches to unusual and under-explored environments.

Western Bats as a Reservoir of Novel Streptomyces Species with Antifungal Activity

“…It is also possible some of these taxa are only present as spores as a result of microbial dispersal in caves. Stable beneficial interactions between Streptomyces and many organisms are common, but they have not been reported yet in vertebrates (43). This study confirms that caves and bats are a rich reservoir of novel species, with the potential for the discovery of novel antifungal compounds, but additional work is necessary to determine the nature of these bacterial associations with bats.…”

Taxonomy, Physiology, and Natural Products of Actinobacteria

“…Insect-bacterium symbioses are widespread in the environment (458), and antibiotic-producing bacterial symbionts are often recruited to protect the host and/or their resources (459,460). Many insects (e.g., ants, termites, gall midges, and beetles) have developed a specific association with their microbial communities.…”

“…Microbial communities of many groups of insects have been widely studied (462), and particularly complex associations have been documented between gut bacteria and insects (463,464). Attine ants have evolved a mutualism with Actinobacteria that produce antibiotics that the ants use as weedkillers to keep their fungal gardens free of other microbes (460,465). For instance, the ants (genera Atta and Acromyrmex) cut leaves and then masticate them into a fine biomass that is fed to the symbiotic fungus (Leucoagaricus gongylophorus) which, in turn, provides lipid-and carbohydrate-rich hyphae known as gongylidia that will be used by the ants (466).…”

Diversity and Antimicrobial Activity of Actinomycetes from Fecal Sample of Rhinoceros Beetle Larvae

“…이들 곤충의 표피나 장에는 다양한 미생물이 공생하고 있 어 곤충의 생장과 대사활동에 큰 영향을 주고 있다 (Scott et al, 2008;Kikuchi, 2009;Seipke et al, 2012). 특히, 곤충들의 체내 혹은 체외에 서식하면서 다양한 생리활성 물질을 생산하는 방선 균과 숙주와의 상호관계에 대해서 최근 활발하게 연구되고 있다 (O'Brien and Wright, 2011;Seipke et al, 2011).…”