Biofilms: Even Stickier Than SuspectedMarch 13, 2009Biofilms are everywhere - in dental plaque and ear canals, on contact lenses and in water pipelines - and the bacteria that make them get more resilient with age, finds a new study in FEMS Microbiology Letters. Because bacteria in biofilms resist antibiotics, the study may have long-term implications for medical researchers seeking to develop better drugs and less infection-prone devices. Biofilms are bacterial cities clinging to a surface. In addition to aiding infections, they can hamper industrial processes by clogging pipelines and gumming up machinery. And as the study shows, biofilms may hold lessons for scholars of evolution. Authors Steven Finkel and Alison Kraigsley of USC College found evidence of natural selection in a single-species bacterial biofilm. Finkel is associate professor of molecular biology. Kraigsley is a graduate student in Finkel's group. "The bacteria that originally formed the biofilm are not the same as the bacteria that we harvest from that same biofilm later," Finkel said. "The mutants we find are more fit than the original founding strain." A 2007 paper by Hansen et al. in the journal Science had found evidence of natural selection in bacterial biofilms, but only in response to competition between species. The new study shows directly that bacteria in biofilms can evolve as a result of starvation or other external pressures. "We demonstrate here for the first time that a single species of biofilm-forming bacteria can evolve in response to changing environmental conditions," the authors wrote. Finkel and Kraigsley incubated biofilms of E. coli bacteria for as long as 33 days, representing potentially hundreds of generations of growth. They then removed bacteria from old biofilms and pitted them against bacteria from very young biofilms. The goal was to see which group would become dominant through sheer numbers of offspring. "We never observed one-day-old biofilm-harvested cells outcompeting older cells at any time point," the authors stated. To guard against the possibility that the older populations might simply be more accustomed to the biofilm environment, rather than genetically different, the researchers placed the cells in a neutral culture for 20 generations before starting the competition. The cells from the older biofilms still outgrew their competitors, suggesting that the advantage was rooted in their genes. The microbes' ability to multiply through multiple generations very quickly makes them ideal model systems for the study of natural selection. The biofilm experiment is a variation on the Finkel group's best-known work: their studies of how starvation of microbes in a closed environment leads to the emergence of a dominant type of cells known as GASP mutants, for Growth Advantage in Stationary Phase. GASPers, as Finkel calls them, outcompete bacteria from younger cultures. The key is not the age of individual microbes but the age of the culture they come from: young offspring of GASPers exhibit the same dominance as their parents. The study was published online Feb. 23. Funding for the study came from the National Science Foundation and the U.S. Air Force Office of Scientific Research. University of Southern California |
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| Related Biofilms Current Events and Biofilms News Articles Bacteria 'launch a shield' to resist attack Researchers from the University of Copenhagen and the Technical University of Denmark along with other collaborators in Denmark and the US found that the bacterium Pseudomonas aeruginosa can 'switch on' production of molecules that kill white blood cells - preventing the bacteria being eliminated by the body's immune system. UTSA biology researchers demystify elusive war zone bacterium Tao Weitao, a researcher in the College of Sciences' Department of Biology at the University of Texas at San Antonio is making great strides in a project that was funded one year ago by the San Antonio Area Foundation. Test helps in fight against lung infections and for treating other life-threatening infections A new test developed by Edmonton-based Innovotech™ Inc. will now allow doctors to more accurately identify the right antibiotics required to treat serious, chronic infections that are biofilm based. New lab-on-a-chip measures mechanics of bacteria colonies Researchers at the University of Michigan have devised a microscale tool to help them understand the mechanical behavior of biofilms, slimy colonies of bacteria involved in most human infectious diseases. Plant Microbe Shares Features with Drug-Resistant Pathogen An international team of scientists has discovered extensive similarities between a strain of bacteria commonly associated with plants and one increasingly linked to opportunistic infections in hospital patients. Cool plasma packs heat against biofilms Though it looks like a tiny purple blowtorch, a pencil-sized plume of plasma on the tip of a small probe remains at room temperature as it swiftly dismantles tough bacterial colonies deep inside a human tooth. Texas A&M researchers examine 'invading' bacteria in DNA Researchers at Texas A&M University's Artie McFerrin Department of Chemical Engineering have discovered how certain types of bacteria integrate the DNA that they have captured from invading enemies into their own genetic makeup to increase their chances of survival. hus the bile does not overflow A consequence of the different cancers of the hepatobiliary system is blocked bile ducts. However, artificial catheters known as "stents" can remediate this problem. Corrosion-inhibiting coatings containing 'good' bacteria A new, environmentally friendly coating that protects metals against corrosion in seawater has been developed by a team of researchers from Sheffield Hallam University. Genes that make bacteria make up their minds Bacteria are single cell organisms with no nervous system or brain. So how do individual bacterial cells living as part of a complex community called a biofilm "decide" between different physiological processes (such as movement or producing the "glue" that forms the biofilm)? More Biofilms Current Events and Biofilms News Articles |
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