Project description:Microbial autotroph-heterotroph interactions influence biogeochemical cycles on a global scale, but the diversity and complexity of natural systems and their intractability to in situ manipulation make it challenging to elucidate the principles governing these interactions. The study of assembling phototrophic biofilm communities provides a robust means to identify such interactions and evaluate their contributions to the recruitment and maintenance of phylogenetic and functional diversity overtime. To examine primary succession in phototrophic communities, we isolated two unicyanobacterial consortia from the microbial mat in HotLake, Washington, characterizing the membership and metabolic function of each consortium. We then analyzed the spatial structures and quantified the community compositions of their assembling biofilms. The consortia retained the same suite of heterotrophic species, identified as abundant members of the mat and assigned to Alphaproteobacteria, Gammaproteobacteria, and Bacteroidetes. Autotroph growth rates dominated early in assembly, yielding to increasing heterotroph growth rates late in succession. The two consortia exhibited similar assembly patterns, with increasing relative abundances of members from Bacteroidetes and Alphaproteobacteria concurrent with decreasing relative abundances of those from Gamma proteobacteria. Despite these similarities at higher taxonomic levels, the relative abundances of individual heterotrophic species were substantially different in the developing consortial biofilms. This suggests that, although similar niches are created by the cyanobacterial metabolisms, the resulting webs of autotroph-heterotroph and heterotroph-heterotroph interactions are specific to each primary producer. The relative simplicity and tractability of the Hot Lake unicyanobacterial consortia make them useful model systems for deciphering interspecies interactions and assembly principles relevant to natural microbial communities.
Project description:Gemmatimonas phototrophica is the only phototrophic member of the recently discovered bacterial phylum Gemmatimonadetes. It was isolated from a freshwater lake in the Gobi desert and first described in 2014. So far, Gemmatimonas phototrophica is the only bacterium to have received a complete set of photosynthesis-related genes by horizontal gene transfer from an ancient phototrophic species from the phylum Proteobacteria. This organism illustrates the possibility for engineering phototrophic capability in a non-phototrophic organism and is therefore of great interest to the field of synthetic biology. The structure of the photosynthetic reaction center-light harvesting 1 complex is under investigation by cryo-EM. Proteomic analysis verified the identities of the expected protein components of this complex and, additionally revealed polypeptides that were previously undiscovered and could be mapped to the cryo-EM images.
Project description:Cryptomonas sp. was grown under phototrophic conditions, glucose supplemented phototrophic conditions and 3 different dissolved organic carbon (DOC) concentrations: 1.5, 30 and 90 mg C l−1. The objective was to study the adaptations that make Cryptomonas sp. thrive under high DOC conditions.
