Project description:The ecological role of pelagic methylotrophic bacteria assessed by high-resolution in situ analysis and autecology of isolated strains
Project description:We investigated microbial communities active in methane oxidation in lake sediment at different oxygen tensions and their response to the addition of nitrate, via stable isotope probing combined with deep metagenomic sequencing. Communities from a total of four manipulated microcosms were analyzed, supplied with (13)C-methane in, respectively, ambient air, ambient air with the addition of nitrate, nitrogen atmosphere and nitrogen atmosphere with the addition of nitrate, and these were compared to the community from an unamended sediment sample. We found that the major group involved in methane oxidation in both aerobic and microaerobic conditions were members of the family Methylococcaceae, dominated by species of the genus Methylobacter, and these were stimulated by nitrate in aerobic but not microaerobic conditions. In aerobic conditions, we also noted a pronounced response to both methane and nitrate by members of the family Methylophilaceae that are non-methane-oxidizing methylotrophs, and predominantly by the members of the genus Methylotenera. The relevant abundances of the Methylococcaceae and the Methylophilaceae and their coordinated response to methane and nitrate suggest that these species may be engaged in cooperative behavior, the nature of which remains unknown.
Project description:Sargassum is one of the most diverse brown algal genus with more than 150 known species, mostly benthic and few pelagic species. They contribute significantly to global primary production and serve as important habitat for wide range of marine organisms. Sargassum vulgare is one of the dominant habitat forming species along Mediterranean coast. Despite their huge ecological importance, it is relatively unknown how they will respond under future global climate change scenario. This work used de novo transcriptome sequencing approach to understand the molecular response of S. vulgare to chronic acidification at the shallow underwater volcanic CO2 vents off Ischia Island, Italy. Keywords: brown algae, Sargassum, de novo transcriptome, ocean acidification, CO2 vents.
Project description:A total gene expression approach was applied to study the methylotrophic nature of B. methanolicus by comparing the gene expression in bacteria grown methylotropic compared to non-methylotrophic. Genes of interest with different gene expression were quantified in the same RNA samples by real-time PCR, confirming the results found in the microarray experiment. Genes of special interest that are expressed higher when grown methylotrophic, were the RuMP pathway genes located on the pBM19.
Project description:A total gene expression approach was applied to study the methylotrophic nature of B. methanolicus by comparing the gene expression in bacteria grown methylotropic compared to non-methylotrophic. Genes of interest with different gene expression were quantified in the same RNA samples by real-time PCR, confirming the results found in the microarray experiment. Genes of special interest that are expressed higher when grown methylotrophic, were the RuMP pathway genes located on the pBM19. Bacillus methanolicus was grown in minimal media with either methanol or mannitol as carbon source. The experiment was preformed in triplicate, with bacterial cultures grown on 3 different days.
Project description:Profiles of dissolved O(2) and methane with increasing depth were generated for Lake Washington sediment, which suggested the zone of methane oxidation is limited to the top 0.8 cm of the sediment. Methane oxidation potentials were measured for 0.5-cm layers down to 1.5 cm and found to be relatively constant at 270 to 350 micromol/liter of sediment/h. Approximately 65% of the methane was oxidized to cell material or metabolites, a signature suggestive of type I methanotrophs. Eleven methanotroph strains were isolated from the lake sediment and analyzed. Five of these strains classed as type I, while six were classed as type II strains by 16S rRNA gene sequence analysis. Southern hybridization analysis with oligonucleotide probes detected, on average, one to two copies of pmoA and one to three copies of 16S rRNA genes. Only one restriction length polymorphism pattern was shown for pmoA genes in each isolate, and in cases where, sequencing was done, the pmoA copies were found to be almost identical. PCR primers were developed for mmoX which amplified 1.2-kb regions from all six strains that tested positive for cytoplasmic soluble methane mono-oxygenase (sMMO) activity. Phylogenetic analysis of the translated PCR products with published mmoX sequences showed that MmoX falls into two distinct clusters, one containing the orthologs from type I strains and another containing the orthologs from type II strains. The presence of sMMO-containing Methylomonas strains in a pristine freshwater lake environment suggests that these methanotrophs are more widespread than has been previously thought.
