The Agricultural Research Service (ARS) of the U. S. Department of Agriculture (USDA) has maintained a collection of nitrogen-fixing bacterial legume symbionts for most of the last century. Some of the initial isolates (cultures accessed in 1913) originated from the Arlington Farm in Northern Virginia, which is now the site of the Pentagon. The ARS did not directly fund the activities of the collection. The collection of strains grew, especially in the 1930s and 1940s, in response to the requirements of research programs in the USA. During this time and throughout the 1950s and 1960s the scientists at USDA produced inoculants for small scale research programs at universities as well as those of other government establishments. At this time the collection had already earned an international reputation.
During the 1970s, an awareness of the critical importance of biological nitrogen fixation in agricultural production ensued because of the energy crisis brought about by the oil embargo. It was quite evident that the limitation of nitrogen in agriculture was a world-wide phenomenon and that poor nations suffered the most because of the rising energy cost. The result was that it became increasingly necessary to rely on the production of leguminous crops and the management of the nitrogen-fixing symbiosis to provide mankind with food, raw materials, and alternative energy sources. Within this climate, the need for a culture collection of characterized legume microbial symbionts was identified during the first three North American Rhizobium conferences. The USDA at Beltsville was unanimously recognized as possessing the most comprehensive collection of strains, and the established links with the public and private sectors were considered advantageous for technology transfer.
Because the goals of the culture collection were relevant at the international level, funding for activities was at first provided by the Agency for International Development (USAID). This support was responsible for the establishment of the basic infrastructure in the laboratory to preserve and record characteristics of the accessions of the collection. One of the objectives of USAID's funding was to provide a means by which scientists of developing nations could preserve their cultures and guard against their loss. The International status of the collection was further advanced during the 1980s by its designation as a Microbiological Resource Center (MIRCEN) by the United Nations Educational and Cultural Organization and the United Nations Environmental Program (UNESCO/UNEP).
ARS, in recognition of the importance of the collection, initiated funding when USAID support ended in 1990. Although funding from USAID for international activities ceased, the collection continues to honor its international obligations in the UNESCO program, and the activities associated with the objectives of the MIRCENs remain active. The collection also became the repository for the type strains of the genera and species of the legume nitrogen-fixing microbial symbionts in 1993.