Project description:The hydrothermal vent gammaproteobacterium Thiomicrospira crunogena inhabits an unstable environment and must endure dramatic sweeps in habitat chemistry. This sulfur chemolithoautotroph responds to changes in dissolved inorganic carbon (DIC; = CO2 + HCO3- + CO3-2) availability with a carbon concentrating mechanism (CCM), in which whole-cell affinity for DIC, as well as the intracellular DIC concentration, increase substantially under DIC-limitation. To determine whether this CCM is regulated at the level of transcription, cells cultivated under high-DIC conditions in chemostats were resuspended in growth medium with low concentrations of DIC, and CCM development was tracked in the presence and absence of RNA polymerase inhibitor rifampicin. The induction of the CCM, as measured by silicone oil centrifugation, was hindered in the presence of rifampicin. Similar results were observed for carboxysome gene transcription and assembly, as assayed by qRT-PCR and transmission electron microscopy, respectively. Genome-wide transcription patterns, assayed via microarrays, were compared for cells grown under DIC-limitation versus ammonia limitation. In addition to carboxysome genes, two novel genes (Tcr_1019 and Tcr_1315), present in other organisms including chemolithoautotrophs, but whose function(s) have not been elucidated in any organism, were found to be upregulated under low-DIC conditions. Likewise, under ammonia limitation, in addition to the expected enhancement of ammonia transporter and PII-gene transcription, the transcription of two novel genes was measurably enhanced (Tcr_0466 and Tcr_2018). Upregulation of all four genes was verified via qRT-PCR (Tcr_1019: 4-fold; Tcr_1315: ~7-fold; Tcr_0466: >200-fold; Tcr_2018: 7-fold), suggesting novel components are part of the response to nutrient limitation by this organism. In this study Thiomicrospira crunogena cells were grown under inorganic carbon limitation and ammonia limitation (high inorganic carbon concentrations) to examine genome wide transcription responses
Project description:The hydrothermal vent gammaproteobacterium Thiomicrospira crunogena inhabits an unstable environment and must endure dramatic sweeps in habitat chemistry. This sulfur chemolithoautotroph responds to changes in dissolved inorganic carbon (DIC; = CO2 + HCO3- + CO3-2) availability with a carbon concentrating mechanism (CCM), in which whole-cell affinity for DIC, as well as the intracellular DIC concentration, increase substantially under DIC-limitation. To determine whether this CCM is regulated at the level of transcription, cells cultivated under high-DIC conditions in chemostats were resuspended in growth medium with low concentrations of DIC, and CCM development was tracked in the presence and absence of RNA polymerase inhibitor rifampicin. The induction of the CCM, as measured by silicone oil centrifugation, was hindered in the presence of rifampicin. Similar results were observed for carboxysome gene transcription and assembly, as assayed by qRT-PCR and transmission electron microscopy, respectively. Genome-wide transcription patterns, assayed via microarrays, were compared for cells grown under DIC-limitation versus ammonia limitation. In addition to carboxysome genes, two novel genes (Tcr_1019 and Tcr_1315), present in other organisms including chemolithoautotrophs, but whose function(s) have not been elucidated in any organism, were found to be upregulated under low-DIC conditions. Likewise, under ammonia limitation, in addition to the expected enhancement of ammonia transporter and PII-gene transcription, the transcription of two novel genes was measurably enhanced (Tcr_0466 and Tcr_2018). Upregulation of all four genes was verified via qRT-PCR (Tcr_1019: 4-fold; Tcr_1315: ~7-fold; Tcr_0466: >200-fold; Tcr_2018: 7-fold), suggesting novel components are part of the response to nutrient limitation by this organism.
Project description:The available energy and carbon sources for prokaryotes in the deep ocean remain still largely enigmatic. Reduced sulfur compounds, such as thiosulfate, are a potential energy source for both auto- and heterotrophic marine prokaryotes. Shipboard experiments performed in the North Atlantic using Labrador Sea Water (~2000 m depth) amended with thiosulfate led to an enhanced prokaryotic dissolved inorganic carbon (DIC) fixation.
Project description:Nitrosomonas europaea is a Gram-negative obligate chemolithoautotroph that derives energy for growth through oxidation of ammonia and participates in the process of nitrification in global nitrogen cycling. The physiological, proteomic, and transcriptional responses of N. europaea to zinc stress were studied. The nitrite production rate and ammonia-dependent oxygen uptake rate of the cells exposed to 3.4 uM ZnCl2 decreased about 61 % and 69 % within 30 minutes, respectively. Two proteins were notably up regulated in zinc treatment and the mRNA levels of their encoding genes started to increase by one hour after the addition of zinc. A total of 27 genes were up regulated and 30 genes were down regulated. Up-regulated genes included mercury resistance genes (merACDPT), inorganic ion transport genes, oxidative stress genes, toxin-antitoxin genes (TA) and two-component signal transduction systems genes. The merACDPT was the highest up regulated operon (46-fold). Down-regulated genes included the RuBisCO operon (cbbO), carbohydrate transporter (mrsA and mnxG) and amino acid transporter. Keywords: zinc, stress response, global transcription, mercury resistance genes, inorganic ion transport genes, oxidative stress genes
Project description:In this study, we investigated the metabolic potential of N. marina based on its complete genome sequence and performed physiological experiments to test genome-derived hypotheses. Our data confirm that N. marina benefits from additions of undefined organic carbon substrates, has adaptations to resist oxidative, osmotic and UV light-induced stress and low dissolved pCO2. Additionally, N. marina is able to grow chemoorganotrophically on formate, and is thus not an obligate chemolithoautotroph. We further investigated the metabolic response of N. marina to low (5.6 µM) O2 concentrations. In response to O2-limited conditions, the abundance of a potentially more efficient CO2-fixing pyruvate:ferredoxin oxidoreductase (POR) complex and a high-affinity cbb3-type terminal oxidase increased, suggesting a role in sustaining nitrite oxidation-driven autotrophy under O2 limitation.
Project description:Candidatus Pelagibacter ubique is the most abundant marine microorganism, but is unable to utilize inorganic sulfur compounds that are plentiful in the ocean. To investigate how these cells adapt to organic sulfur limitation, batch cultures were grown in defined media containing either limiting or non-limiting amounts of dimethylsulfoniopropionate (DMSP) as the sole sulfur source. Protein and mRNA expression were measured during exponential growth, immediately prior to stationary phase, and in late stationary phase. Two distinct responses were observed: one as DMSP approached exhaustion, and another after the DMSP supply was depleted. The first response was characterized by increased transcription and translation of all Ca. P. ubique genes downstream of previously confirmed S-adenosyl methionine (SAM) riboswitches: bhmT, mmuM, and metY. These genes were up to 33 times more abundant during low DMSP conditions and shunt all available sulfur to methionine. The osmotically inducible organic hydroperoxidase OsmC was the most up-regulated protein as DMSP (an osmolyte) became scarce. The second response, during sulfur-depleted stationary phase, saw increased transcription of the heme c shuttle ccmC and two small genes of unknown function (SAR11_1163 and SAR11_1164) which were 6-10 times higher in sulfur-starved cultures. No known membrane transporters were up-regulated in response to sulfur limitation, suggesting that this bacterium's strategy for coping with sulfur stress focuses on intracellularly redistributing, rather than importing, organic sulfur compounds. This supports the conclusion that the few organosulfur molecules that Ca. P. ubique is able to metabolize are rarely limiting in the marine environment. Batch cultures of P. ubique were grown in a defined arificial seawater media. Five cultures were amended with a limiting concentration of DMSP as the sole sulfur source and another four control cultures were amended with a non-limiting DMSP concentration. Cultures were harvested for microarray analyses at multiple timepoints for the purpose of observing differences in gene expression related to sulfur limitation. Proteomic analyses were conducted in parallel and are available at https://www.ebi.ac.uk/pride/archive/projects/PXD003672 .
Project description:Candidatus Pelagibacter ubique is the most abundant marine microorganism, but is unable to utilize inorganic sulfur compounds that are plentiful in the ocean. To investigate how these cells adapt to organic sulfur limitation, batch cultures were grown in defined media containing either limiting or non-limiting amounts of dimethylsulfoniopropionate (DMSP) as the sole sulfur source. Protein and mRNA expression were measured during exponential growth, immediately prior to stationary phase, and in late stationary phase. Two distinct responses were observed: one as DMSP approached exhaustion, and another after the DMSP supply was depleted. The first response was characterized by increased transcription and translation of all Ca. P. ubique genes downstream of previously confirmed S-adenosyl methionine (SAM) riboswitches: bhmT, mmuM, and metY. These genes were up to 33 times more abundant during low DMSP conditions and shunt all available sulfur to methionine. The osmotically inducible organic hydroperoxidase OsmC was the most up-regulated protein as DMSP (an osmolyte) became scarce. The second response, during sulfur-depleted stationary phase, saw increased transcription of the heme c shuttle ccmC and two small genes of unknown function (SAR11_1163 and SAR11_1164) which were 6-10 times higher in sulfur-starved cultures. No known membrane transporters were up-regulated in response to sulfur limitation, suggesting that this bacterium's strategy for coping with sulfur stress focuses on intracellularly redistributing, rather than importing, organic sulfur compounds. This supports the conclusion that the few organosulfur molecules that Ca. P. ubique is able to metabolize are rarely limiting in the marine environment.
Project description:Diatoms represent one of the largest groups of Stramenopiles. In the phytoplankton biodiversity, they dominate oceanic and freshwater ecosystems, and contribute significantly to biogeochemical cycles. They are primary producers at the base of food webs, capturing dissolved CO2, inorganic nitrogen, phosphorus, sulfur, etc., and are important carriers of carbon and silicon to the ocean interior. Whereas extensive studies of P. tricornutum response to a lack of nitrogen have been reported from transcriptomics to metabolomics and lipidomics, changes occurring at the proteome level are still missing. Here we aimed at providing a reference dataset, corresponding to the proteomic changes occurring when Phaeodactylum tricornutum cells were cultivated in either a nitrogen-rich or a nitrogen-poor medium.