Published online 1 December 2011 Nucleic Acids Research, 2012, Vol. 40, Database issue D57–D63 doi:10.1093/nar/gkr1163 BioProject and BioSample databases at NCBI: facilitating capture and organization of metadata Tanya Barrett, Karen Clark, Robert Gevorgyan, Vyacheslav Gorelenkov, Eugene Gribov, Ilene Karsch-Mizrachi*, Michael Kimelman, Kim D. Pruitt, Sergei Resenchuk, Tatiana Tatusova, Eugene Yaschenko and James Ostell National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, 45 Center Drive, Bethesda, MD 20892, USA Received October 12, 2011; Revised November 10, 2011; Accepted November 11, 2011 ABSTRACT As the volume and complexity of data sets archived at NCBI grow rapidly, so does the need to gather and organize the associated metadata. Although metadata has been collected for some archival databases, previously, there was no centralized approach at NCBI for collecting this information and using it across databases. The BioProject database was recently established to facilitate organization and classification of project data submitted to NCBI, EBI and DDBJ databases. It captures descriptive information about research projects that result in high volume submissions to archival databases, ties together related data across multiple archives and serves as a central portal by which to inform users of data availability. Concomitantly, the BioSample database is being de- veloped to capture descriptive information about the biological samples investigated in projects. BioProject and BioSample records link to corres- ponding data stored in archival repositories. Submissions are supported by a web-based Submission Portal that guides users through a series of forms for input of rich metadata describing their projects and samples. Together, these data- bases offer improved ways for users to query, locate, integrate and interpret the masses of data held in NCBI’s archival repositories. The BioProject and BioSample databases are available at http:// www.ncbi.nlm.nih.gov/bioproject and http://www .ncbi.nlm.nih.gov/biosample, respectively. INTRODUCTION The National Center for Biotechnology Information (NCBI) hosts several primary archive databases that store numerous categories of biological data produced by the research community. Data types include, but are not limited to, full and partial genomes, transcriptomes, epigenomes, genetic variation and phenotype data. The NCBI and International Nucleotide Sequence Database Collaboration (INSDC) (1) archival databases hosting these data include GenBank (2), SRA (3), GEO (4), Epigenomics (5), dbSNP (6), dbVar (7) and dbGaP (8). As the diversity, complexity, inter-relatedness and rate of generation of these data continue to grow, it is becoming increasingly important to organize and annotate the data such that users can more easily locate, understand and analyze data that are relevant to their interests. The BioProject and BioSample databases were recently initiated to help address these needs by facilitating the capture and management of structured metadata and data for diverse biological research projects and samples represented in NCBI’s archival databases. The BioProject database replaces NCBI’s Genome Project database and reﬂects an expansion of project scope, a redesigned database structure and a redesigned website. BioProject serves as a central portal in which to represent the higher order organization, description and classiﬁcation of data submitted across several NCBI archival databases. It constitutes a ﬂexible framework in which to describe a project’s scope and objectives, to group related projects and subprojects and to collate derived data records which would be otherwise dispersed. The BioSample database provides a dedicated area in which to describe the biological materials under investiga- tion in a project and promotes the use of structured *To whom correspondence should be addressed. Tel: +301 435 5929; Fax: +301 480 2918; Email: mizrachi@ncbi.nlm.nih.gov Published by Oxford University Press 2011. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.