The production of antibiotics by Streptomyces after actinomycete-actinomycete interaction with Pseudonocardia sp. PIP161 characterized by increased sporulation

Current discovery of novel antibiotics from actinomycetes is hindered by replication of compounds from common Streptomyces and the finding that a large portion of potentially active compounds is locked behind unexpressed genes. Interaction with other microorganisms, such as fungi and bacteria, has previously shown to produce novel compounds which are not produced when grown in axenic conditions. However, only little progress have been made in the research and screening of interactions which may exist among the more uncommon actinomycetes, in particular with producer Streptomyces. This research focuses on screening the interaction between 24 non-Streptomyces from the genus Pseudonocardia, Kribbella, Amycolatopsis and Micromonospora and ten Streptomyces for activity against Staphylococcus aureus. Triplicate screening has discovered 30 (both one-way and two-way) interactions in form of increased or decreased growth and sporulation rate, increased or decreased pigmentation or production of diffusible pigments, and the increased production of antibiotics compared to the individual microorganisms alone. Further investigations into the production of antibiotics are warranted due to cell-to-cell interactions between Pseudonocardia sp. PIP 161 and Streptomyces sp. EUM 76, Streptomyces sp. EUM 244, and Streptomyces sp. PIP 146, after 10 days incubation on ISP-2 medium. In all interactions, the antibiotic compounds are produced by Streptomyces and characterized by a noticeable increase of sporulation. However, sporulation alone cannot indicate production of antibiotics as interaction between Streptomyces sp. EUM 76 with Nocardia and Micromonospora did not result in antibiotic activity despite increased sporulation. This study attempts to pinpoint the mode of interaction between Pseudonocardia and Streptomyces.