Presentation Date


Hosting Institution

California State University, Sacramento


Sacramento, California

Document Type




Supporting Program


Faculty Mentor

Gregory C. Palmer


Mono-culture, co-culture, streptomyces, interspecies interactions, zones of inhibition, 16S rRNA


There is a need to discover antibiotics that currently don’t exist to combat the rise in antibiotic resistant within pathogenic bacteria by using Streptomyces, a genus of bacteria that are a major source of antibiotics. Matthew Traxler et al. found that interspecies interactions of Streptomyces coelicolor with different actinomycetes grown in co-culture led to the production of secondary metabolites that S. coelicolor had not been known to produce. This suggests that chemical cooperation between actinomycetes may shift secondary metabolite production of S. coelicolor. Many of the bacteria co-cultured with S. coelicolor produce antibiotics, and it is possible that antibiotics themselves could induce secondary metabolite production in cross-species communication. This project tested whether antibiotics could be a mechanism by which interspecies interactions induce antibiotic production. A strain of Streptomyces was isolated from a soil sample acquired at the University of Texas at Austin and identified by amplification and sequencing of the isolates’ 16S rRNA genes and identified the species as Streptomyces osmaniensis. To determine if interspecies interactions could increase antibiotic production, the inhibitory effects of co-cultures were compared to that of mono-cultures against a strain of Pseudomonas. Interestingly, extracts from co-cultures of Streptomyces osmaniensis with Streptomyces coelicolor, both wild-type and mutant species, produced significantly smaller zones of inhibition compared to S. osmaniensis grown in mono-culture. Zones of inhibition were significantly smaller for extracts from co-cultures with S. coelicolor wild-type. These results suggest that antibiotics are not mediators of enhanced secondary metabolite production that is often observed in co-culture experiments.