Project description:Marine Synechococcus, together with Prochlorococcus, contribute to a significant proportion of the primary production on Earth. The spatial distribution of these two groups of marine picocyanobacteria depends on different factors such as nutrients availability or temperature. Some Synechococcus ecotypes thrive in mesotrophic and moderately oligotrophic waters, where they exploit both oxidized and reduced forms of nitrogen. Here, we present a comprehensive study, which includes transcriptomic and proteomic analyses of the response of Synechococcus sp. strain WH7803 to nanomolar concentrations of nitrate, compared to ammonium or nitrogen starvation. We found that Synechococcus has a specific response to nanomolar nitrate concentration that differs to the response showed under nitrogen starvation or the presence of standard concentrations of either ammonium or nitrate. This fact suggests that the particular response to the uptake of nanomolar concentration of nitrate could be an evolutionary advantage for marine Synechococcus against Prochlorococcus in the natural field.
Project description:Prochlorococcus is the most abundant photosynthetic organism on Earth, contributing significantly to the global primary production and playing a prominent role in biogeochemical cycles. Prochlorococcus requires the capability to accommodate to environmental changes in order to proliferate in oligotrophic oceans, in particular regarding nitrogen availability. A precise knowledge of the composition and changes of the proteome is necessary to gain fundamental insights into such response. Here we study the effects of extreme nitrogen limitation, a feature of the oligotrophic oceans inhabited by this organism.
Project description:This study is aimed to isolate marine actinomycetes from sediments from Andaman and the Gulf of Thailand. All 101 marine actinomycetes were screened for anti-biofilm activity. Streptomyces sp. GKU223 showed significantly inhibited biofilm formation of S. aureus. The evaluation of supernatants of anti-biofilm activity produced by Streptomyces sp. GKU223 has been performed. Since the interaction between marine actinomycetes and biofilm forming bacteria has never been investigated, proteomic analysis has been used to identify whole cell proteins involved in anti–biofilm activity. Understanding the interaction at molecular level will lead to sustainably use for anti-biofilm producing marine actinomycetes in pharmaceutical and medicinal applications in the future.
Project description:This study is aimed to isolate marine actinomycetes from sediments from Andaman and the Gulf of Thailand. All 101 marine actinomycetes were screened for anti-biofilm activity. Streptomyces sp. GKU 257-1 showed significantly inhibited biofilm formation of E. coli. The evaluation of supernatants of anti-biofilm activity produced by Streptomyces sp. GKU 257-1 has been performed. Since the interaction between marine actinomycetes and biofilm forming bacteria has never been investigated, proteomic analysis has been used to identify whole cell proteins involved in anti–biofilm activity. Understanding the interaction at molecular level will lead to sustainably use for anti-biofilm producing marine actinomycetes in pharmaceutical and medicinal applications in the future.
Project description:Chlorella sp. HS2 is a halotolerant microalga exhibiting relatively high biomass productivity and substantially high lipid accumulation in marine growth media, which suggests this alga as an important crop for industrial algal cultivation systems. To determine pathways leading to HS2's acclimation responses to salt stress, we performed RNA-seq analysis with triplicated cultures grown in freshwater and marine media at both exponential and stationary growth phases. We then run de novo assembly to obtain HS2 transcriptome, which in turn was annotated and processed to extract dysregulated pathways. Results showed a large proportion of down-regulated genes, for instance photosynthesis and TCA pathways. Photosynthesis appeared, however, to recover at the stationary phase, while the general down-regulation pattern was maintained.
Project description:Although N2 fixation can occur in free-living cyanobacteria, the unicellular endosymbiotic cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A) is considered to be a dominant N2-fixing species in marine ecosystems. Four UCYN-A sublineages are known from partial nitrogenase (nifH) gene sequences. However, few studies have investigated their habitat preferences and regulation by their respective hosts in open-ocean versus coastal environments. Here, we compared UCYN-A transcriptomes from oligotrophic open-ocean versus nutrient-rich coastal waters. UCYN-A1 metabolism was more impacted by habitat changes than UCYN-A2. However, across habitats and sublineages genes for nitrogen fixation and energy production were highly transcribed. Curiously these genes, critical to the symbiosis for the exchange of fixed nitrogen for fixed carbon, maintained the same schedule of diel expression across habitats and UCYN-A sublineages, including UCYN-A3 in the open-ocean transcriptomes. Our results undersore the importance of nitrogen fixation in UCYN-A symbioses across habitats, with consequences for community interaction and global biogeochemical cycles.
Project description:Primary productivity of open ocean environments, such as those inhabited by marine picocyanobacteria Synechococcus sp.WH8102, are often limited by low inorganic phosphate (P). To observe how this organism copes with P starvation, we constructed a full genome microarray and examined differences in gene expression under P-limited and P-replete growth conditions. To determine the temporal nature of the responses, comparisons were made for cells newly entered into P-stress (at a time point corresponding to the induction of extracellular alkaline phosphatase activity) and a later time point (late log phase). In almost all instances the P starvation response was transitory, with 36 genes showing significant upregulation (>log2 fold) while 23 genes were highly downregulated at the early time point; however, these changes in expression were maintained for only five of the upregulated genes. Knockout mutants were constructed for genes SYNW0947 or SYNW0948, comprising a two component regulator hypothesized to play a key role in regulating the response to P-limitation. A high degree of overlap in the sets of genes affected by P-limited conditions and in the knockout mutants supports this hypothesis; however there is some indication that other regulators may play a role in this response in Synechococcus sp. WH8102. Consistent with what has been observed in many other cyanobacteria, the Pho regulon of this strain is comprised largely of genes for alkaline phosphatases, P transport or P metabolism. Interestingly, however, the exact composition and arrangement of the Pho regulon appears highly variable in marine cyanobacteria.
Project description:Protein expression in Staphylococcus sp. NIOSBK35 isolated from marine environment (mangrove sediments) to different concentrations of arsenic (III)