Project description:We established simple synthetic microbial communities in a microcosm model system to determine the mechanisms that underlay cross-feeding in microbial methane-consuming communities. Co-occurring strains from Lake Washington sediment were used that are involved in methane consumption, a methanotroph and two non-methanotrophic methylotrophs.
Project description:Microbial communities respond to temperature with physiological adaptation and compositional turnover. Whether thermal selection of enzymes explains marine microbiome plasticity in response to temperature remains unresolved. By quantifying the thermal behaviour of seven functionally-independent enzyme classes (esterase, extradiol dioxygenase, phosphatase, beta-galactosidase, nuclease, transaminase, and aldo-keto reductase) in native proteomes of marine sediment microbiomes from the Irish Sea to the southern Red Sea, we record a significant effect of the mean annual temperature (MAT) on enzyme’s response (R2, 0.51–0.80, p < 0.01 in all cases). Activity and stability profiles of 228 esterases and 5 extradiol dioxygenases from sediment and seawater across 70 locations worldwide (latitude 62.2°S–16°N, MAT –1.4ºC–29.5ºC) validate this thermal pattern. Modelling the esterase phase transition temperature as a measure of structural flexibility, confirm the observed relationship with MAT. Furthermore, when considering temperature variability in sites with non-significantly different MATs, the broadest range of enzyme thermal behaviour and the highest growth plasticity of the enriched heterotrophic bacteria occur in samples with the widest annual thermal variability. These results indicate that temperature-driven enzyme selection shapes microbiome thermal plasticity and that thermal variability finely tunes such processes and should be considered alongside MAT in forecasting microbial community thermal response
Project description:Chemical analysis of the compounds present in sediment, although informative, often is not indicative of the downstream biological effects that these contaminants exert on resident aquatic organisms. More direct molecular methods are needed to determine if marine life is affected by exposure to sediments. In this study, we used an aquatic multispecies microarray and q-PCR to investigate the effects on gene expression in juvenile sea bream (Sparus aurata) of two contaminated sediments defined as sediment 1 and 2 respectively, from marine areas in Northern Italy.
Project description:Marine snow plays a central role in carbon cycling. It consists of organic particles and particle-associated (PA) microbMarine snow plays a central role in carbon cycling. It consists of organic particles and particle-associated (PA) microbial communities that are embedded in a sugary matrix. Metaproteomic analysis offers the unique opportunity to gain unprecedented insight into the microbial community composition and biomolecular activity of environmental samples. In order to realize this potential for marine PA microbial communities, new methods of protein extraction must be developed. In this study, we used 1D-SDS-PAGEs and LC-MS/MS to compare the efficiency of six established protein extraction protocols for their applicability of metaproteomic analyses of the PA microbial community in the North Sea. A combination of SDS-buffer extraction and bead beating resulted in the greatest number of identified protein groups. As expected, a metagenomic database of the same environmental sample increased the number of protein identification by approximately 50%. To demonstrate the application of our established protocol, particulate bacterioplankton samples collected during spring phytoplankton bloom in 2009 near the island Helgoland, were analysed by a GeLC-MS/MS-based metaproteomic approach. Our results indicated that there are only slight differences in the taxonomical distribution between free-living (FL) and PA bacteria but that the abundance of protein groups involved in polysaccharide degradation, motility and particle specific stress (oxygen limitation, nutrient limitation, heavy metal stress) is higher in the PA fractions. ial communities that are embedded in a sugary matrix. Metaproteomic analysis offers the unique opportunity to gain unprecedented insight into the microbial community composition and biomolecular activity of environmental samples. In order to realize this potential for marine PA microbial communities, new methods of protein extraction must be developed. In this study, we used 1D-SDS-PAGEs and LC-MS/MS to compare the efficiency of six established protein extraction protocols for the their applicability of metaproteomic analyses of the PA microbial community in the North Sea. A combination of SDS-buffer extraction and bead beating resulted in the greatest number of identified protein groups. As expected, a metagenomic database of the same environmental sample increased the number of protein identification by approximately 50%. To demonstrate the application of our established protocol, particulate bacterioplankton samples collected during spring phytoplankton bloom in 2009 near the island Helgoland, were analysed by a GeLC-MS/MS-based metaproteomic approach. Our results indicated that there are only slight differences in the taxonomical distribution between free-living (FL) and PA bacteria but that the abundance of protein groups involved in polysaccharide degradation, motility and particle specific stress (oxygen limitation, nutrient limitation, heavy metal stress) is higher in the PA fractions.
Project description:Metagenomic approaches have revealed unprecedented genetic diversity within microbial communities across vast expanses of the world’s oceans. Linking this genetic diversity with key metabolic and cellular activities of microbial assemblages is a fundamental challenge. Here we report on a collaborative effort to design MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories), a high-density oligonucleotide microarray that targets functional genes of diverse taxa in pelagic and coastal marine microbial communities. MicroTOOLs integrates nucleotide sequence information from disparate data types: genomes, PCR-amplicons, metagenomes, and metatranscriptomes. It targets 19 400 unique sequences over 145 different genes that are relevant to stress responses and microbial metabolism across the three domains of life and viruses. MicroTOOLs was used in a proof-of-concept experiment that compared the functional responses of microbial communities following Fe and P enrichments of surface water samples from the North Pacific Subtropical Gyre. We detected transcription of 68% of the gene targets across major taxonomic groups, and the pattern of transcription indicated relief from Fe limitation and transition to N limitation in some taxa. Prochlorococcus (eHLI), Synechococcus (sub-cluster 5.3) and Alphaproteobacteria SAR11 clade (HIMB59) showed the strongest responses to the Fe enrichment. In addition, members of uncharacterized lineages also responded. The MicroTOOLs microarray provides a robust tool for comprehensive characterization of major functional groups of microbes in the open ocean, and the design can be easily amended for specific environments and research questions.
Project description:Marine microbial communities are critical for biogeochemical cycles and the productivity of ocean ecosystems. Primary productivity, at the base of marine food webs, is constrained by nutrient availability in the surface ocean, and nutrient advection from deeper waters can fuel photosynthesis. In this study, we compared the transcriptional responses by surface microbial communities after experimental deep water mixing to the transcriptional patterns of in situ microbial communities collected with high-resolution automated sampling during a bloom in the North Pacific Subtropical Gyre. Transcriptional responses were assayed with the MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories) marine environmental microarray, which targets all three domains of life and viruses. The experiments showed that mixing of deep and surface waters substantially affects the transcription of photosystem and nutrient response genes among photosynthetic taxa within 24 hours, and that there are specific responses associated with the addition of deep water containing particles (organisms and detritus) compared to filtered deep water. In situ gene transcription was most similar to that in surface water experiments with deep water additions, showing that in situ populations were affected by mixing of nutrients at the six sampling sites. Together, these results show the value of targeted metatranscriptomes for assessing the physiological status of complex microbial communities.
Project description:The objective was to identify functional genes encoded by Fungi and fungal-like organisms to assess putative ecological roles Using the GeoChip microarray, we detected fungal genes involved in the complete assimilation of nitrate and the degradation of lignin, as well as evidence for Partitiviridae (a mycovirus) that likely regulates fungal populations in the marine environment. These results demonstrate the potential for fungi to degrade terrigenously-sourced molecules, such as permafrost and compete with algae for nitrate during blooms. Ultimately, these data suggest that marine fungi could be as important in oceanic ecosystems as they are in freshwater environments.