Microorganisms - ENVIS Centre

Deciphering Bacterial Doomsday Decisions

As a homeowner preparing 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.

Source: www.phys.org

Scientists believe that prior to the advent of DNA as the earth’s primary genetic material, early forms of life used RNA to encode genetic instructions. What sort of genetic molecules did life rely on before RNA? The answer may be AEG, a small molecule that when linked into chains form a hypothetical backbone for peptide nucleic acids (PNA), which have been hypothesized as the first genetic molecules. Synthetic AEG has been studied by the pharmaceutical industry as a possible gene silencer to stop or slow certain genetic diseases. The only problem with the theory is that up to now, AEG has been unknown in nature. A team of scientists from the USA and Sweden announced that they have discovered AEG within cyanobacteria which are believed to be some of the most primitive organisms on earth. “While we were writing our manuscript”, Dr. Cox says, “we learned that our colleagues at the Stockholm University Department of Analytical Chemistry had made a similar discovery, so we asked them to join us on the paper”. To determine how widespread AEG production is among cyanobacteria, the scientists analyzed pristine cyanobacterial cultures from the Pasteur Culture Collection of Paris, France.

Cyanobacteria can survive in extreme habitats is remarkable, such as the hot springs of Yellowstone National Park.