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In the human world of manufacturing, many companies are nowapplying an on-demand, just-in-time strategy to conserve resources,reduce costs and promote production of goods precisely when andwhere they are most needed. A recent study from Indiana UniversityBloomington scientists reveals that bacteria have evolved a similarjust-in-time strategy to constrain production of an extremelysticky cement to exactly the appropriate time and place, avoidingwasteful and problematic production of the material. Indiana University biologists and two physicists at BrownUniversity with IU connections have shown that certain bacteriawait until the last minute to synthesize the glue that allows themto attach permanently to surfaces. Binding efficiently to surfacesis extremely important to bacteria in the environment and forbacterial disease agents during the infection process. The researchers found that bacteria -- including the freshwaterbacterium Caulobacter crescentus and the agricultural pathogen Agrobacterium tumefaciens -- firstconnect to a surface with the cellular equivalents of propellersand cables and that this initial, reversible contact stimulates thesynthesis of a sticky glue. This holdfast adhesin, which iscomposed of polysaccharide sugar molecules, is then released onlyat the site of surface contact to irreversibly attach the bacteriato host surfaces. The study, "Surface contact stimulates the just-in-time deploymentof bacterial adhesins," was published earlier this month in Molecular Microbiology . It describes how single bacterial cells use their flagella (thepropellers) and pili (the cables) to facilitate the timely releaseof adhesive polysaccharides upon initial contact with othersurfaces. Microbiologists are generally interested in bacterial adhesion andformation of complex microbial communities called biofilms that canclog pipes, slow down ships and establish antibiotic-resistantinfections. Efficient surface attachment strategies areadvantageous to bacteria as they can increase nutrient access andresistance to environmental stress , including host defenses. "For bacteria, surface attachment by single cells is the first stepto important processes such as biofilm formation and hostinfection," said IU microbiologist Pamela Brown, one of theproject's lead authors. "What we found is that the interaction ofbacterial cells with a surface using their flagellum and pilistimulates the on-the-spot production of polysaccharide adhesins,propelling the transition from transient to permanent attachment." The new findings also suggest that pathogenic bacteria maycarefully time adhesin release to protect themselves from prematureexposure to a host's immune system during infection. The team used cutting-edge, high-resolution video microscopy toobserve the single-cell attachment process in real time in thepresence of a fluorescent stain that decorates the adhesivepolysaccharide. They found that when Caulobacter cells arepropelled to a surface by their rotating propeller-like singleflagellum, the flagellar motor stopped immediately upon contactwith the surface. Inhibition of flagellar rotation was quicklyfollowed by the production of the holdfast polysaccharide adhesin,specifically from the cell pole containing the now inactiveflagellum, and in contact with the surface. "We knew that cable-like pili are present at the same pole of thecell as the flagellum, and we hypothesized that they played a keyrole in the process by interacting with the surface, therebypreventing the free rotation of the flagellum," said IUmicrobiologist Yves Brun, the project's principal investigator.Indeed, when the team made a mutation that abolished the pili, thecells became tethered to the surface by their flagellum, but itsrotation continued and the cell eventually detached. The team hypothesizes that just-in-time adhesin production may be ageneral phenomenon since they obtained similar results with twoother bacterial species, Agrobacterium tumefaciens and Asticcacaulis biprosthecum. "What is striking is that we found that this mechanism does morethan stimulate binding to inert surfaces. It also operates when theplant pathogen Agrobacterium tumefaciens binds to host tissue,"said IU microbiologist Clay Fuqua, who recently discovered theholdfast-type adhesin used by this bacterium to attach to planttissue. "We think that the ability to rapidly deploy this permanentadhesin may be advantageous for swimming cells attempting tocolonize a favorable environment." Since pathogens such as Escherichia coli and Pseudomonas aeruginosa also attach by their pole prior to their transition fromreversible to irreversible attachment, the authors hypothesize thatthis mechanism could also be at play during the infection process. "Once we know more about the details of this mechanism, we may beable to design drugs that prevent this adhesin stimulation,therefore reducing the efficiency of infections," Brown said. Research from Brun's laboratory and that of Brown Universityphysicist Jay Tang on bacterial glues published in 2006* receivedinternational attention after they showed that the holdfast "glue"released by the tiny Caulobacter cells was the strongest in naturewith a pulling force of 1 micronewton, equivalent to holding threeor four cars with glue spread on the surface of a quarter. "For such a strong adhesive, it may be important to avoid producingit too early because it might lose its efficiency, or it might getthe cells irreversibly bound to the wrong surface. The analogy tothe human world is amazing: You don't apply glue hours before youwant to use it because it cures and hardens," Brun said. Timing is everything, and with just-in-time adhesive production,cells have a better chance for efficient surface interaction andcolonization because the two main factors in reducing adhesion --curing and coating of glue with small particles -- are inhibitorymechanisms that require time to decrease adhesiveness. Theon-the-spot production of adhesins circumvents this problem. Additional References Citations. The e-commerce company in China offers quality products such as China Cell Phone Leather Cases , Nylon Canvas Bag Manufacturer, and more. For more , please visit Tablet Protective Film today!
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