Project description:Dynamic environmental factors such as light, nutrients, salt, and temperature continuously affect chlorophototrophic microbial mats, requiring adaptive and acclimative responses to stabilize composition and function. Quantitative metabolomics analysis can provide insights into metabolite dynamics for understanding community response to such changing environmental conditions. In this study, we quantified volatile organic acids, polar metabolites (amino acids, glycolytic and citric acid cycle intermediates, nucleobases, nucleosides, and sugars), wax esters, and polyhydroxyalkanoates, resulting in the identification of 104 metabolites and related molecules in thermal chlorophototrophic microbial mat cores collected over a diel cycle in Mushroom Spring, Yellowstone National Park. A limited number of predominant taxa inhabit this community and their functional potentials have been previously identified through metagenomics and metatranscriptomic analyses and in situ metabolisms, and metabolic interactions among these taxa have been hypothesized. Our metabolomics results confirmed the diel cycling of photorespiration (e.g., glycolate) and fermentation (e.g., acetate, propionate, and lactate) products, the carbon storage polymers polyhydroxyalkanoates, and dissolved gasses (e.g., H2 and CO2) in the waters overlying the mat, which were hypothesized to occur in major mat chlorophototrophic community members. In addition, we have formulated the following new hypotheses: (1) the morning hours are a time of biosynthesis of amino acids, DNA, and RNA; (2) photo-inhibited cells may also produce lactate via fermentation as an alternate metabolism; (3) glycolate and lactate are exchanged among Synechococcus and Roseiflexus spp.; and (4) fluctuations in many metabolite pools (e.g., waxesters) at different times of day result from species found at different depths within the mat responding to temporal differences in their niches.
Project description:Omics approaches employed to study biological molecules have revolutionized environmental microbiology and elevated our understanding of ecological processes in the biosphere. However, conventional omics applications often lead to the loss of information about macromolecular organization of the molecules within the cellular context. This can be a significant disadvantage since many proteins are functional only as macromolecular complexes in particular structural forms. A great example is bacterial contractile injection system (CIS), a syringe-like protein complex whose function is the translocation of molecules into a target cell to affect its state, often inducing lysis. Since the function of CIS is tightly linked to its intracellular localization, proteomics cannot confidently predict the function of novel uncharacterized CISs in natura. To overcome this challenge, we have developed a cryo-electron tomography workflow as a technique complementing metagenomics and proteomics. Additionally, we developed an immuno-electron microscopy protocol to identify and quantify CIS particles in environmental samples. Using this approach, we discovered a novel bacterial CIS in thermophilic multicellular Chloroflexota bacteria populating hot spring mats worldwide. We found that this system is similar phylogenetically and structurally to a recently described cytoplasmic CIS, which was found in multicellular Streptomyces and has been shown to be involved in cell cycle regulation. Interestingly, using our approaches, we have discovered that Chloroflexota cells produce different numbers of CIS particles depending on the mat micro-niches they occupy. In agreement with this, we observed that CIS was also non-constitutively expressed under laboratory conditions. Motivated by this discovery, we searched and analyzed similar CIS in extremophilic bacteria from other lineages. Overall, we have gained an understanding that bacterial cytoplasmic CIS is an overlooked cellular feature of the extremophilic bacteria, which is potentially involved in the cell fate control or intraspecies interaction within microbial community.
Project description:Hot spring phototrophic mat microbial communities from Octopus Spring, Yellowstone National Park, Wyoming, United States - 20050623_t1 metagenome
Project description:Hot spring phototrophic mat microbial communities from Mushroom Spring, Yellowstone National Park, Wyoming, United States - 20050630_ee2 metagenome
Project description:Hot spring phototrophic mat microbial communities from Mushroom Spring, Yellowstone National Park, Wyoming, United States - 20050701_me2 metagenome