Project description:Increasing atmospheric CO2 concentrations are causing decreased pH over vast expanses of the ocean. This decreasing pH may alter biogeochemical cycling of carbon and nitrogen via the microbial process of nitrification, a key process that couples these cycles in the ocean, but which is often sensitive to acidic conditions. Recent reports indicate a decrease in oceanic nitrification rates under experimentally lowered pH. How composition and abundance of ammonia oxidizing bacteria (AOB) and archaea (AOA) assemblages respond to decreasing oceanic pH, however, is unknown. We sampled microbes from two different acidification experiments and used a combination of qPCR and functional gene microarrays for the ammonia monooxygenase gene (amoA) to assess how acidification alters the structure of ammonia oxidizer assemblages. We show that despite widely different experimental conditions, acidification consistently altered the community composition of AOB by increasing the relative abundance of taxa related to the Nitrosomonas ureae clade. In one experiment this increase was sufficient to cause an increase in the overall abundance of AOB. There were no systematic shifts in the community structure or abundance of AOA in either experiment. These different responses to acidification underscore the important role of microbial community structure in the resiliency of marine ecosystems. SUBMITTER_CITATION: Title: Acidification alters the composition of ammonia oxidizing microbial assemblages in marine mesocosms Journal: Marine Ecology Progress Series Issue: 492 Pages: 1-8 DOI: 10.3354/meps 10526 Authors: Jennifer L Bowen Patrick J Kearns Michael Holcomb Bess B Ward
Project description:The results obtained in this study will further enrich the molecular developmental biology information of conchs and even marine bivalves. They provide important clues for elucidating the early embryonic development mechanisms of conchs and offer theoretical guidance for breakthroughs in the artificial cultivation techniques of N. arthritica cumingii.
Project description:Cyanobacterial blooms associated with the benthic mat have been rising. Besides the ongoing concern about toxins production, cyanobacteria are actively involved in marine biofilms, representing several economic and environmental impacts. Proteomic studies on cyanobacterial biofilms could be an effective approach to establish metabolic pathways that affect these fouling organisms and, consequently, obtain novel control strategies against them. Currently, there are few studies in this field on filamentous cyanobacteria. Thus, standard methodologies for following cyanobacterial biofilm development for a long-term assay and a quantitative proteomics analysis were performed in this work. Biofilm development from unidentified filamentous Synechococcales LEGE 06021 was evaluated on different surfaces, glass and perspex, and at two significant shear rates for marine environments (4 s-1 and 40 s-1). Higher biofilm development was observed at 4 s-1, and these biofilms showed a lower roughness coefficient value than those formed at higher shear. Overall, about 1,877 proteins were identified, and differences in proteome were more noticeable between the two hydrodynamic conditions than those found between the two surfaces. 20 Differentially Expressed Proteins (DEPs) were found between 4 s-1 vs. 40 s-1, of which 15 DEPs were found on glass, whereas five DEPs were found on perspex. On the glass, some of these DEPs include phage tail proteins, orange carotenoid protein, enzymes like cyanophynase, glutathione-dependent formaldehyde dehydrogenase, and MoaD/ThiS family protein, while on perspex, the DEPs include enzymes such as transketolase, dihydroxy-acid dehydratase, iron ABC transporter substrate-binding protein or transcription termination/antitermination protein NusG. In summary, the biofilm structure, chlorophyll a content, total biomass, and proteomic profile are more affected by the hydrodynamic conditions than by the surfaces employed. These findings suggest that most of the metabolic changes could be produced to counterbalance the different shear rates. However, the differential expression of some proteins could be associated with the surfaces used. This study helps to consolidate the knowledge of the main factors affecting biofilm development, and sheds new lights on putative targets to address new antimicrobial strategies.
Project description:To characterize the taxonomic and functional diversity of biofilms on plastics in marine environments, plastic pellets (PE and PS, ø 3mm) and wooden pellets (as organic control) were incubated at three stations: at the Baltic Sea coast in Heiligendamm (coast), in a dead branch of the river Warnow in Warnemünde (inlet), and in the Warnow estuary (estuary). After two weeks of incubation, all pellets were frozen for subsequent metagenome sequencing and metaproteomic analysis. Biofilm communities in the samples were compared on multiple levels: a) between the two plastic materials, b) between the individual incubation sites, and c) between the plastic materials and the wooden control. Using a semiquantitative approach, we established metaproteome profiles, which reflect the dominant taxonomic groups as well as abundant metabolic functions in the respective samples.
Project description:Increasing atmospheric CO2 concentrations are causing decreased pH over vast expanses of the ocean. This decreasing pH may alter biogeochemical cycling of carbon and nitrogen via the microbial process of nitrification, a key process that couples these cycles in the ocean, but which is often sensitive to acidic conditions. Recent reports indicate a decrease in oceanic nitrification rates under experimentally lowered pH. How composition and abundance of ammonia oxidizing bacteria (AOB) and archaea (AOA) assemblages respond to decreasing oceanic pH, however, is unknown. We sampled microbes from two different acidification experiments and used a combination of qPCR and functional gene microarrays for the ammonia monooxygenase gene (amoA) to assess how acidification alters the structure of ammonia oxidizer assemblages. We show that despite widely different experimental conditions, acidification consistently altered the community composition of AOB by increasing the relative abundance of taxa related to the Nitrosomonas ureae clade. In one experiment this increase was sufficient to cause an increase in the overall abundance of AOB. There were no systematic shifts in the community structure or abundance of AOA in either experiment. These different responses to acidification underscore the important role of microbial community structure in the resiliency of marine ecosystems. amoA gene diversity from two ocean acidification experiments, Monterey Bay experiment (two time points, ambient and acidified) and Vineyard Sound experiment (ambient and acifidied, with and without nutrients) examined with 2 two-color arrays (Cy3 and Cy5): the universal standard 20-mer oligo is printed to the slide with a 70-mer oligo (an archetype). Environmental DNA sequences (fluoresced with Cy3) within 15% of the 70-mer conjugated to a 20-mer oligo (fluoresced with Cy5) complementary to the universal standard will bind to the oligo probes on the array. Signal is the ratio of Cy3 to Cy5.
Project description:Extracellular polymeric substances (EPS) produced by bacteria form a matrix for the complex three-dimensional architecture of biofilms. The EPS matrix of a biofilm is primarily composed of polysaccharides, proteins and extracellular DNA (eDNA). In addition to supporting the community structure, the EPS matrix protects bacterial biofilms from the environment. Specifically, the EPS matrix reduces the penetration of antimicrobial agents into the biofilm, thereby reducing their efficiency. Strategies for disrupting the formation of the EPS matrix can therefore lead to a more efficient use of antimicrobial agents. Here, we examine the biofilm-disrupting activity of vitamin C (sodium ascorbate). Quantitative proteomics analysis of vitamin C treated biofilms show that exposure to vitamin C inhibits quorum sensing and other regulatory mechanisms underpinning biofilm development. This results in inhibition of the EPS biosynthesis, and depletion of the polysaccharide component of the matrix. Once the EPS content is reduced beyond a critical point, bacterial cells get fully exposed to the medium, thereby experiencing a planktonic-like state. At this stage, the cells are more susceptible to killing, either by vitamin C-induced oxidative stress as reported here, or by other antibacterial compounds or treatments.
Project description:Competition for limited iron resources is a key driver of microbial community structure in many regions of the surface ocean. The bacterial siderophores ferrioxamine and amphibactin have been identified in marine surface waters, suggesting that they may represent an important bacterial strategy for obtaining iron from a scarcely populated pool. We screened several strains of marine Vibrio for the presence of putative amphibactin biosynthesis gene homologues and amphibactin production. Whole cell proteomics, siderophore isolation, and isotopically labeled iron uptake experiments were performed. Here, we show that an amphibactin-producing marine bacterium, Vibrio cyclitrophicus str. 1F-53, harbors an independently regulated uptake pathway for ferrioxamines. Proteomic analyses identified upregulation of the amphibactin NRPS system and a putative amphibactin siderophore transporter in response to low iron concentrations. In addition, multiple other transporters were upregulated, however when desferrioxamine was present, amphibactin production decreased and the ferrioxamine receptor increased in abundance. Such cheating phenotypes, which appear widespread among marine amphibactin producers, highlight the strategies that contribute to the fitness of marine bacteria in the face of iron stress. These results demonstrate siderophore producer and cheater phenotypes and highlight the cellular restructuring which is involved due to competition for iron, that shapes the community structure of marine ecosystems.
Project description:Biofilms offer an excellent example of ecological interaction among bacteria. Temporal and spatial oscillations in biofilms are an emerging topic. In this paper, we describe the metabolic oscillations in Bacillus subtilis biofilms by applying the smallest theoretical chemical reaction system showing Hopf bifurcation proposed by Wilhelm and Heinrich in 1995. The system involves three differential equations and a single bilinear term. We specifically select parameters that are suitable for the biological scenario of biofilm oscillations. We perform computer simulations and a detailed analysis of the system including bifurcation analysis and quasi-steady-state approximation. We also discuss the feedback structure of the system and the correspondence of the simulations to biological observations. Our theoretical work suggests potential scenarios about the oscillatory behaviour of biofilms and also serves as an application of a previously described chemical oscillator to a biological system.