While secondary metabolites are organic compounds that are considered to be nonessential for survival, bacteria are known to produce these compounds for important specialized functions. Some secondary metabolites inhibit or destroy competitors. Others are signals to control transitions between cellular states, such as biofilm formation and swarming. Traditional studies of secondary metabolites involve purified molecules that are tested on isolated species. However, bacteria predominantly exist in complex multi-species communities, which select for robust competitive mechanisms. Therefore the question as to how networks of secondary metabolites function in the competition between species is not addressed by such traditional approaches. This NSF CAREER project focuses on examining mixed-species cultures that expands the range of detectable bioactive metabolites and their competitive functions. Based on preliminary data that indicate several secreted metabolites are exchanged between Bacillus subtilis and Streptomyces sp. Mg1, microbial genetics in combination with physiological and developmental analyses will be used to determine the role of the compounds in the competition between these two species for limited resources. Further, studies of metabolic activity will be integrated with innovative imaging mass spectrometry to assess the net impact of multiple active metabolites. Secreted enzymes that contribute to the competitive success of the species producing the secondary metabolites will also be identified. This project will provide a new view of secondary metabolic networks in bacterial competition.
Broader Impacts The research goals of this project are interwoven with education and outreach programs to promote public awareness and understanding of natural sources of antibiotics, which are microbial secondary metabolites, and their metabolism. The education program will produce and disseminate basic knowledge of bacterial ecology, metabolism, and synthesis of secondary metabolites via coursework and laboratory studies that focus on microbial interactions and emphasize a changing perspective on bacteria from single pathogenic entities to communal organisms. The coursework also includes database development and web-based interfaces accessible to students and the public, and so is integrated with the outreach program, which will convey the same basic knowledge to wider audiences.
