A series of tests in Boston\'s subways will measure the performance of new bioterrorism sensors developed to detect biological agents, U.S. officials said. The \"Detect-to-Protect\" Bio Detection project will assess several sensors developed by U.S. companies and designed to alert authorities to the presence of biological material, the U.S. Department of Homeland Security\'s Science and Technology Directorate reported Friday. These devices with \"trigger\" and \"confirmer\" sensors are intended to identify and confirm the release of biological agents within minutes, it said. The tests will see the release of a small amount of an innocuous killed bacterium in subway stations in the Boston area to test how well the sensors work. After the subway stations close, scientists will spray small quantities of killed Bacillus subtilis in subway tunnels. The common, food-grade bacterium is widely found in soil, water, air and decomposing plant matter and, even when living, is considered nontoxic to humans, animals and plants, directorate scientists said. \"While there is no known threat of a biological attack on subway systems in the United States, the S&T testing will help determine whether the new sensors can quickly detect biological agents in order to trigger a public safety response as quickly as possible,\" Anne Hultgren, manager of the project, said. The testing will continue periodically for the next six months, officials said, and will be monitored by the Massachusetts Bay Transportation Authority as well as state and local public health officials.