Project description:Algal bacterial interactions in phycosphere microbial communities have important implications for the stability and productivity of algal biofuel systems, and algal metabolites are important mediators of those interactions. We characterized exometabolites and cell associated metabolites from the model diatom Phaeodactylum tricornutum across different growth stages.
Project description:Eutrophication can lead to an uncontrollable increase in algal biomass, which has repercussions for the entire microbial and pelagic community. Studies have shown how nutrient enrichment affects microbial species succession, however details regarding the impact on community functionality are rare. Here, we applied a metaproteomic approach to investigate the functional changes to algal and bacterial communities, over time, in oligotrophic and eutrophic conditions, in freshwater microcosms. Samples were taken early during algal and cyanobacterial dominance and later under bacterial dominance. 1048 proteins, from the two treatments and two timepoints, were identified and quantified by their exponentially modified protein abundance index. In oligotrophic conditions, Bacteroidetes express extracellular hydrolases and Ton-B dependent receptors to degrade and transport high molecular weight compounds captured while attached to the phycosphere. Alpha- and Beta-proteobacteria were found to capture different substrates from algal exudate (carbohydrates and amino acids, respectively) suggesting resource partitioning to avoid direct competition. In eutrophic conditions, environmental adaptation proteins from cyanobacteria suggested better resilience compared to algae in a low carbon nutrient enriched environment. This study provides insight into differences in functional microbial processes between oligo- and eutrophic conditions at different timepoints and highlights how primary producers control bacterial resources in freshwater environments.
Project description:We quantified bacterial incorporation of algal-derived complex dissolved organic C (DOC) and N (DON) and net algal incorporation of remineralized C and N at the single cell level using isotope tracing and NanoSIMS for fifteen bacterial co-cultures growing with the diatom Phaeodactylum tricornutum, and examined the expressed proteins of two of the isolates when growing with P. tricornutum. Data was searched with MS-GF+ using PNNL's DMS Processing pipeline.
2022-08-24 | MSV000090201 | MassIVE
Project description:Bacterial assemblage detected from 150 strains of harmful algal cultures
| PRJNA771505 | ENA
Project description:Bacterial communities of protists cultures
Project description:For the filamentous cyanobacterium Anabaena variabilis to grow without combined nitrogen, certain cells differentiate into heterocysts that fix N2, while vegetative cells perform photosynthesis. Much remains unknown on how heterocysts differ from vegetative cells in terms of carbon and energy metabolisms. Microarrays were used to investigate gene transcription patterns in vegetative cells, heterocysts, and filaments of N2-fixing phototrophic, mixotrophic, and heterotrophic cultures.
Project description:Unicellular algae, termed phytoplankton, greatly impact the marine environment by serving as the basis of marine food webs and by playing central roles in biogeochemical cycling of elements. The interactions between phytoplankton and heterotrophic bacteria affect the fitness of both partners. It is becoming increasingly understood that metabolic exchange determines the nature of such interactions, but the underlying molecular mechanisms remain underexplored. Here, we investigated the molecular and metabolic basis for the bacterial lifestyle switch, from coexistence to pathogenicity, in Sulfitobacter D7 during interactions with Emiliania huxleyi, a cosmopolitan bloom-forming phytoplankter. The interaction displays two distinct phases: first, there is a coexisting phase in which the alga grows exponentially and the bacterium grows as well. The interaction shifts to pathogenic when the virulence of Sulfitobacter D7 towards E. huxleyi is invoked upon exposure to high concentrations of algal dimethylsulfoniopropionate (DMSP), which occurs when the algae reach stationary growth or when DMSP is applied exogenously to algae in exponential growth. We aimed to unravel the response of Sulfitobacter D7 to the pathogenicity-inducing compound, DMSP, and to different algae-derived infochemicals that affect the lifestyle of the bacterium. We grew Sulfitobacter D7 in conditioned media (CM) derived from algal cultures at the different growth phases, exponential and stationary (Exp-CM and Stat-CM, respectively), in which DMSP concentration is low and high, respectively. This enabled us to separate between different phases of the interaction with E. huxleyi, i.e., Exp-CM representing the coexisting phase, and Stat-CM representing the pathogenic phase. An additional pathogenicity-inducing treatment was Exp-CM supplemented with 100 µM DMSP (herein Exp-CM+DMSP). This condition mimicked co-cultures to which we added DMSP exogenously and thus induced Sulfitobacter D7 pathogenicity, which lead to death of exponentially growing E. huxleyi. In order to identify bacterial genes that are specifically responsive to DMSP, and are not affected by other algae-derived factors, we grew Sulfitobacter D7 in defined minimal medium (MM), lacking algal metabolites, supplemented with 100 µM DMSP (herein MM+DMSP), and examined the transcriptional response. After 24 h of Sulfitobacter D7 growth in all 5 media, triplicates were taken for transcriptomic analysis. Altogether, this experimental design allowed to expand our understanding on the bacterial response to DMSP, algal infochemicals and which of these are essential for coexistence and pathogenicity.
Project description:Four Fe(II) concentrations (0.03, 0.09, 0.12 & 0.75 mM) were tested to investigate the stimulation and inhibition effects of ferrous iron on anammox bacterial activity. RNAs were extracted from the cultures, and the synthesized cDNAs by reverse transcription were used to carry out GeoChip analysis, by which the functional communities and expression level differences in functional genes under different Fe(II) concentrations conditions were obtained, and the response of anammox bacteria to Fe(II) stimulation and inhibition are speculated.
2020-08-28 | GSE120704 | GEO
Project description:High abundance bacterial strains isolated from algal cultures in a eutrophic lake