{"id":43796,"date":"2020-08-10T15:44:00","date_gmt":"2020-08-10T12:44:00","guid":{"rendered":"https:\/\/en.buradabiliyorum.com\/deprived-of-oxygen-layers-of-bacteria-get-creative\/"},"modified":"2020-08-10T15:44:00","modified_gmt":"2020-08-10T12:44:00","slug":"deprived-of-oxygen-layers-of-bacteria-get-creative","status":"publish","type":"post","link":"https:\/\/buradabiliyorum.com\/en\/deprived-of-oxygen-layers-of-bacteria-get-creative\/","title":{"rendered":"#Deprived of oxygen, layers of bacteria get creative"},"content":{"rendered":"

“#Deprived of oxygen, layers of bacteria get creative<\/strong>”<\/p>\n

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\n This scanning electron micrograph (SEM) shows cells in a fixed Pseudomonas aeruginosa colony biofilm. The crack in this fixed sample reveals the many layers of densely packed cells that make up the biofilm structure. This biofilm mode of life gives these cells protection and can result in antibiotic resistance \/ tolerant infections, but the cells also cause a problem for themselves. The upper biofilm layers respire oxygen faster than it can diffuse to the bottom, effectively suffocating the lower layers. However, these cells have a strategy to overcome this oxygen limitation. Credit: Newman laboratory
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Bacteria are found living nearly everywhere on our planet, from the inside of human intestines to the soil to deep underwater. When scientists study bacteria in the lab, they most often examine individual bacterial cells as they grow rapidly in liquid cultures. However, bacteria in nature usually exist in the form of structures called biofilms\u2014dense populations of cells attached to each other and to surfaces with a matrix of sticky goo.<\/p>\n

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To conserve energy, bacterial cells normally remove electrons from sugars and transfer those electrons to oxygen molecules. While oxygen is plentiful at the surface of a biofilm, there is very little of it at the bottom, creating a puzzle for biologists: How do bacteria buried at the bottom of a thick biofilm “breathe” if they lack ready access to oxygen or other electron acceptors used to conserve energy?<\/p>\n

Bacteria can solve this problem in a variety of ways. In one strategy, bacteria produce so-called extracellular electron shuttles\u2014small, diffusible molecules that are capable of exchanging electrons with a variety of substrates.
\nResearchers in the laboratory of Dianne Newman, Caltech’s Gordon M. Binder\/Amgen Professor of Biology and Geobiology and executive officer for molecular biology, have now made progress toward a mechanistic understanding of this process in an organism called Pseudomonas aeruginosa. P. aeruginosa is a model organism for studying biofilms and extracellular electron shuttles. It is also a dangerous opportunistic pathogen: it caused more than 30,000 hospital-acquired infections in 2019, and it is inherently antibiotic resistant. An understanding of P. aeruginosa’s metabolic processes could lead to new methods to treat these infections more effectively, while offering insight into the workings of many kinds of bacterial biofilms.
\nA paper describing the new study app<\/a>ears on August 6 in the journal Cell<\/i>.
\nBiologists have suspected that the key to a modified metabolism for organisms like P. aeruginosa lies with molecules called phenazines. Researchers in the Newman laboratory have previously shown that bacteria that cannot produce phenazines also cannot form biofilms; instead, they form structures that are so thin that every cell has access to oxygen. In 2016, Newman and her colleagues demonstrated that biofilm development in P. aeruginosa could be inhibited through the addition of an extracellular enzyme that degraded a key phenazine produced by the microbe.
\nIn this new study, the team focused on the matrix of “goo” that holds a biofilm together to discover exactly how phenazines help bacteria breathe without oxygen. The research was led by former graduate student Scott Saunders (Ph.D. ’20) and was conducted in collaboration with researchers in the laboratories of Jacqueline Barton, Caltech’s John G. Kirkwood and Arthur A. Noyes Professor of Chemistry, and Leonard Tender of the Naval Research Laboratory in Washington, D.C.<\/p>\n

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