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Takatomo Fujisawa

Publications and source records attributed to Takatomo Fujisawa.

3 recordsLinked to original sources

Microbiome Datahub: an open-access platform integrating environmental metadata, taxonomy, and functional annotation for comprehensive metagenome-assembled genome datasets.

BACKGROUND: Metagenome-assembled genomes (MAGs) provide crucial insights into the genomic diversity of uncultured microbes. However, MAG datasets deposited in public repositories such as INSDC are often difficult to reuse due to heterogeneous quality, inconsistent taxonomic and functional annotations, and insufficiently curated environmental metadata. While secondary MAG databases such as MGnify, IMG/M, and SPIRE provide standardized resources, they reconstruct MAGs de novo from public metagenomic reads and therefore do not represent the original MAGs reported in publications. RESULTS: To address this gap, we developed Microbiome Datahub, an open-access platform that systematically aggregates and re-annotates original MAGs from INSDC. We collected 214,427 MAGs, predicted genes by DFAST, performed quality assessment with CheckM, standardized taxonomic assignments with GTDB-Tk, inferred 27 phenotypic traits using Bac2Feature, assigned proteins to MBGD ortholog clusters and KEGG Orthology IDs using PZLAST, and annotated environmental metadata with the Metagenome and Microbes Environmental Ontology. Across these MAGs, the average completeness was 80.5% and contamination 1.8%; notably, the most frequent values were&#x2009;>95% completeness and&#x2009;<1% contamination, indicating that the majority of MAGs are of high quality. Comparative analyses showed that Microbiome Datahub provides phylogenetically and environmentally diverse MAGs: while the majority originated from vertebrate gut environments, a substantial number were also recovered from other habitats such as groundwater, including nearly 10,000 MAGs from the Patescibacteria. Inference of 27 phenotypic traits, including optimum growth temperature, further revealed ecological differentiation across phyla. Protein clustering revealed 56 million identity 40% clusters, with the majority unique compared with MGnify and GlobDB, and&#x2009;~19% of proteins unassigned to MBGD ortholog clusters, underscoring their novelty. CONCLUSIONS: Microbiome Datahub integrates MAG genome sequences, gene and protein predictions, quality metrics, environmental and taxonomic annotations, ortholog cluster assignments, and phenotype predictions, all accessible via a web interface, API, and bulk downloads. By combining original MAGs with curated metadata and functional annotations, Microbiome Datahub constitutes a comprehensive and reusable resource that will accelerate microbiome and microbial genomics research. Video Abstract.

Metagenome↗

Sequence analysis of three plasmids harboured in Rhodococcus erythropolis strain PR4.

Rhodococcus erythropolis strain PR4 has been isolated as an alkane-degrading bacterium. The strain harbours one linear plasmid, pREL1 (271 577 bp) and two circular plasmids, pREC1 (104 014 bp) and pREC2 (3637 bp), all with some sequence similarities to other Rhodococcus plasmids. For pREL1, pREC1 and pREC2, 298, 102 and 3 open reading frames, respectively, were predicted. Linear plasmid pREL1 has several regions homologous to plasmid pBD2 found in R. erythropolis BD2. Sequence analysis of pREL1 and pBD2 identified common metal-resistance genes on both, but pREL1 also encodes alkane-degradation genes not found on pBD2, with enzyme constituents some of which are quite different from those of other organisms. The alkane hydroxylase consisted of a cytochrome P450 monooxygenase, a 2Fe-2S ferredoxin, and a ferredoxin reductase. The ferredoxin reductase amino acid sequence resembles the AlkT (rubredoxin reductase) sequence. A zinc-containing alcohol dehydrogenase further oxydizes alkanols, alkane oxidation products catalysed by alkane hydroxylase. Of the circular plasmids, the pREC1 sequence is partially similar to the sequence of pREAT701, the virulence plasmid found in Rhodococcus equi. pREC1 has no pREAT701 virulence genes and encodes genes for beta-oxidation of fatty acids. Thus, joint actions of enzymes encoded by pREL1 and pREC1 may enable efficient mineralization of alkanes.

Base Sequence↗

Use of segment-based microarray in the analysis of global gene expression in response to various environmental stresses in the cyanobacterium Anabaena sp. PCC 7120.

We prepared microarrays that contain genomic sequences of a heterocyst-forming filamentous cyanobacterium Anabaena sp. PCC 7120. The complete genome of this cyanobacterium codes for about 5,368 protein-coding genes in the main chromosome of 6.4 Mbp. In total, 2,407 DNA segments were selected from the sequencing clones, and amplified by PCR, then spotted on glass slides in duplicate. These microarrays differ from the widely used commercial or custom-made ones for other microorganisms in that each DNA segment was 3-4 kbp long, and contained about 3-4 predicted genes on average. This feature, however, did not decrease the usefulness of the microarrays, since we were able to detect a number of potentially novel genes that are induced in response to nitrogen deprivation, low temperature and drought. In addition, we found some genomic regions in which dozens of contiguous genes are simultaneously regulated. These results suggest that these segment-based microarrays are useful especially for such large genomes as Anabaena, for which the number of genes exceeds either technical or practical limitations.

Anabaena↗