Deciphering Bacterial Doomsday Decisions

As a homeowner prepping for a hurricane, the bacterium Bacillus subtilis uses a long checklist to prepare for survival in hard times. In a new study, scientists at Rice University and the University of Houston uncovered an elaborate mechanism that allows B. subtilis to begin preparing for survival, even as it delays the ultimate decision of whether to “hunker down” and withdraw into a hardened spore. The new study by computational biologists at Rice and experimental biologists at the University of Houston was published online on November 19, 2012 in PNAS. “The gene-expression program that B. subtilis uses to form spores involves hundreds of genes,” said Dr. Oleg Igoshin, lead scientist on the study and professor of bioengineering at Rice. “Many of these genes are known and have been studied for decades, but the exact mechanism that B. subtilis uses to make the decision to form a spore has remained a mystery.” B. subtilis is a common soil bacterium that forms a spore when food runs short. Spore formation involves dramatic changes. The cell first asymmetrically divides within its outer wall, forming one large chamber and one small one. As spore formation progresses, one chamber envelopes the other, which becomes a vault for the organism’s DNA and a small set of proteins that can “reboot” the organism when it senses that outside conditions have improved. B. subtilis is harmless to humans, but some dangerous bacteria like anthrax also form spores. Scientists are keen to better understand the process, both to protect public health and to explore the evolution of complex genetic processes. During spore formation, scientists know that a bacterium channels its energy into producing proteins that help prepare the cell to become a spore.
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