Interactions of Different Streptomyces Species and Myxococcus xanthus Affect Myxococcus Development and Induce the Production of DK-Xanthenes

Abstract

The co-culturing of microorganisms is a well-known strategy to study microbial interactions in the laboratory. This approach facilitates the identification of new signals and molecules produced by one species that affects other species’ behavior. In this work, we have studied the effects of the interaction of nine Streptomyces species (S. albidoflavus, S. ambofaciens, S. argillaceus, S. griseus, S. lividans, S. olivaceus, S. parvulus, S. peucetius, and S. rochei) with the predator bacteria Myxococcus xanthus, five of which (S. albidoflavus, S. griseus, S. lividans, S. olivaceus, and S. argillaceus) induce mound formation of M. xanthus on complex media (Casitone Yeast extract (CYE) and Casitone tris (CTT); media on which M. xanthus does not form these aggregates under normal culture conditions. An in-depth study on S. griseus–M. xanthus interactions (the Streptomyces strain producing the strongest effect) has allowed the identification of two siderophores produced by S. griseus, demethylenenocardamine and nocardamine, responsible for this grouping effect over M. xanthus. Experiments using pure commercial nocardamine and different concentrations of FeSO4 show that iron depletion is responsible for the behavior of M. xanthus. Additionally, it was found that molecules, smaller than 3 kDa, produced by S. peucetius can induce the production of DK-xanthenes by M. xanthus.

Antifungal Activity of Streptomyces spp. Extracts In Vitro and on Post-Harvest Tomato Fruits against Plant Pathogenic Fungi

“…Therefore, the coloring of the fungal mycelium could be due to this fungal stimulation, as secondary metabolites of fungi with blue coloring, such as azulenes or atrovenetin produced by Penicillium herquei or Lactarius sp., have also been reported [27]. The literature seems to indicate that one of the crucial aspects of this interaction is the competition for iron, which induces the production of siderophores, triggering the activation of biosynthetic pathways related to the synthesis of secondary metabolites by the actinomycete [14], while small molecules of less than 3 kDa have been identified in the stimulation of M. xanthus [26]. In our case, further studies are needed to determine the nature and origin of this staining.…”

“…Although the production of bioactive secondary metabolites by the genus Streptomyces is well known [24,25], no similar data have been reported for the encapsulation of fungi by Streptomyces mycelium or the compounds related to the color change or staining of fungal mycelium when grown in co-cultures, making these data highly novel. Related results are the induction of the formation of mounds of M. xanthus by several Streptomyces species [26]. The coloring could be due to compounds produced by the actinomycete or the fungus itself.…”

“…For example, there are studies in which co-culture induces the production of metabolites by the actinomycete, as in the case of Streptomyces coelicolor when co-cultured with M. xanthus, which produces curiously blue-colored actinorhodin [13]. In contrast, in other studies, such as with Streptomyces peucetius, co-culture has induced the synthesis of DK-Xanthene by M. xanthus, which is yellow in color [26]. Therefore, the coloring of the fungal mycelium could be due to this fungal stimulation, as secondary metabolites of fungi with blue coloring, such as azulenes or atrovenetin produced by Penicillium herquei or Lactarius sp., have also been reported [27].…”