Project description:Methanogens inhabit euxinic (sulfide-rich) or ferruginous (iron-rich) environments that promote the precipitation of transition metals as metal sulfides, such as pyrite, reducing metal or sulfur availability. Such environments have been common throughout Earth’s history raising the question as to how anaerobes obtain(ed) these elements for the synthesis of enzyme cofactors. Here, we show a methanogen can synthesize molybdenum nitrogenase metallocofactors from pyrite as the source of iron and sulfur, enabling nitrogen fixation. Pyrite-grown, nitrogen-fixing cells grow faster and require 25-fold less molybdenum than cells grown under euxinic conditions. Growth yields are 3 to 8 times higher in cultures grown under ferruginous relative to euxinic conditions. Physiological, transcriptomic, and geochemical data indicate these observations are due to sulfide-promoted metal limitation, in particular molybdenum. These findings suggest that molybdenum nitrogenase may have originated in a ferruginous environment that titrated sulfide to form pyrite, facilitating the availability of sufficient iron, sulfur, and molybdenum for cofactor biosynthesis.
Project description:The pyrite mine of Lousal, Grândola, Portugal, was discovered in 1882 and extensively exploited from 1900 until its closure in 1988 when the mining ores were not viable economically. Aiming at becoming a cultural-touristic center, the mining area was rehabilitated raising a Mining Museum and a Science Centre along with the reopening of a mining gallery for public access. In recent times, aerobiological studies on subterranean environments such as caves, mines and archeological necropolis revealed to be an important source of novel bacteria, from which their biotechnological potential are under study. Here we present a Pseudomonas sp. isolated from the mine air with potential secondary metabolite biosynthesis, resistance to antibiotics and virulence factors.
Project description:Pelagic aggregates function as hotspots for microbial activity and biological carbon pumps for exporting OM fixed by photoautotrophs to sediments in lakes and oceans. In iron-rich (ferruginous) lakes, photoferrotrophic or chemolithoautotrophic bacteria appear to contribute to CO2 fixation by oxidizing reduced iron which leads to the formation of iron-rich pelagic aggregates called iron-snow. In acidic lakes, iron snow is colonized mainly by acidophilic iron-cycling microbes that can trigger interspecies aggregation mechanisms. However, the significance of iron oxidizers in carbon fixation, their general role in iron snow functioning, and the flow of carbon within iron snow is still unclear. Here, we combined a two-year metatranscriptome analysis with a 13CO2 metabolic labeling approach to determine general metabolic activities. Protein-based stable isotope probing (protein-SIP) was used to trace the 13CO2 incorporation in iron snow microcosms over time under both oxic and anoxic conditions. Analysis of our mRNA-derived metatranscriptome data identified four key players (Leptospirillum, Ferrovum, Acidithrix, Acidiphilium) with relative abundances (59.6%-85.7%) in iron snow encoding a variety of ecologically relevant pathways, including carbon fixation, polysaccharide biosynthesis, and flagellar-based motility. We did not detect transcriptional activity for carbon fixation from archaea or eukaryotes. The largest numbers of expressed genes (3008, 2991, 2936) matched to the genomes of our previously obtained iron snow isolates (Acidithrix sp. C25, Acidiphilium sp. C61, Acidocella sp. C78) separately. 13CO2 incorporation studies identified Leptospirillum and Ferrovum, as the main active chemolithoautotrophs under oxic conditions, and Ferrovum was the main active organism under anoxic conditions as well. Small amounts of labeled 13C (Relative isotope abundance: 1.0%-5.3%) were found in the heterotrophic Acidiphilium and Acidocella. Overall, our data show that iron oxidizers play an important role in the formation of iron minerals and CO2 fixation, but the majority of fixed C apparently did not reach other iron snow microbes. This finding suggests that most of the fixed C will be directly exported to the sediment without feeding heterotrophs in the water column in acidic ferruginous lakes.
2022-02-17 | PXD025534 | Pride
Project description:Exploring the Culturable Microbiome Diversity and Biotechnological Potential in Corals
Project description:Iron-sulfur minerals such as pyrite are found in many marine benthic habitats. At deep-sea hydrothermal vent sites they occur as massive sulfide chimneys. Hydrothermal chimneys formed by mineral precipitation from reduced vent fluids upon mixing with cold oxygenated sea water. While microorganisms inhabiting actively venting chimneys and utilizing reduced compounds dissolved in the fluids for energy generation are well studied, only little is known about the microorganisms inhabiting inactive sulfide chimneys. We performed a comprehensive meta-proteogenomic analysis combined with radiometric dating to investigate the diversity and function of microbial communities found on inactive sulfide chimneys of different ages from the Manus Basin (SW Pacific). Our study sheds light on potential lifestyles and ecological niches of yet poorly described bacterial clades dominating inactive chimney communities.
2019-01-02 | PXD010074 | Pride
Project description:Iron Reducing Potential and Community Structure of Iron Reducing Microorganisms in Shale Gas Field
| PRJNA673157 | ENA
Project description:Microbial communities within iron ore caves and associated iron-reducing enrichments
Project description:A high-density oligonucleotide microarray that targets functional genes in marine microbial community was designed as a result of a multi-institutional effort. The design is based on nucleotide sequence data obtained with metagenomics and metatranscriptomics. The chip targets ~20000 gene sequences represented by 145 gene categories relevant to microbial metabolism in the open ocean and coastal environments. The three domains of life and also viruses are represented on the chip. Using this microarray we were able to compare the functional responses of microbial communities to iron and phosphate enrichments in samples from the North Pacific Subtropical Gyre. The response was attributed to individual lineages of microorganisms including uncharacterized strains. Transcription of 68% of the gene probes was detected from a variety of microorganisms, and the patterns of gene transcription indicated a relief from iron limitation and transition into nitrogen limitation. When combined with physicochemical descriptions of each system, the use of microarrays can help to develop a comprehensive understanding of the changes in microbially-driven processes. We analyzed three samples amended with phosphate and two sample amended with iron (III) after 48h of incubation