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12-13_Microbial_Growth___Metabolism_Combo

Listeria monocytogenes cdc investigation announcement

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Listeria monocytogenes CDC Investigation Announcement: As of October 6, 2011, a total of 109 persons infected with outbreak - associated strains of Listeria monocytogenes have been reported from 24 states. All illnesses started on or after July 31, 2011. Twenty - one deaths have been reported: One woman pregnant at the time of illness had a miscarriage. From the Virtual Microbiology Classroom on ScienceProfOnline.com
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Microbes & pH As with temperature, bacteria have minimum, optimum and maximum pH ranges. __________________ Protozoans and most bacteria have an optimum pH range of 6.5 to 7.5. pH range of human organs and tissues. ________________ Most fungi & some bacteria grow best in acid niches. Obligate acidophiles have to live in an acidic environment. Acid- tolerant Microbes will survive in an acid environment, but do not prefer that. Images: Helicobacter pylori , Y. Tsutsumi, M.D., Fujita Health University School of Medicine; pH scale , Edward Stevens Gram-negative , microaerophilic, and acidophilic bacterium. Can thrive in the stomach and upper small intestines and cause ulcers. However, many who are infected do not show any symptoms. Helicobacter spp. only known microorganisms to thrive in highly acidic environment of stomach. Meet the Microbe! From the Virtual Microbiology Classroom on ScienceProfOnline.com
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H 2 O important reactant in many metabolic reactions. Most cells die in absence of water. - Some have cell walls that retain water. Q: What genus comes to mind? - Endospores and cysts can cease most metabolic activity for years. Q: What organisms make endospores? Which make cysts? Cell walls of bacteria prevent them from exploding in a hypotonic environment, but most bacteria are vulnerable in hypertonic environments. Many bacteria can be plasmolyzed by high concentrations of solutes. The water moves out of the bacterium and it dies of ‘hyperosmostic shock’ (desiccation). Images: Water drop , Fir0002 , flagstaffotos.com.au ; : Cells, full of water versus plasmolyzed , Mnolf, Wiki Microbes & Water: Osmotic Pressure Q: Why can you keep honey on the cupboard for months, even years, without it spoiling? From the Virtual Microbiology Classroom on ScienceProfOnline.com
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Glycocalyx & Osmotic Pressure Obligate ______________ Must l ive in a niche of high salt content. Can grow in an environment up to 30% salt. If placed within a freshwater environment, they will burst and die. ____________ Halophiles Can survive and tolerate high salt niches, but do not require them to living. Some bacteria have an additional layer outside of the cell wall called the glycocalyx . One type of glycocalyx is called a _____ ____ glycoproteins loosely associated with the cell wall. cause bacteria to adhere to solid surfaces and help prevent the cell from drying out Meet the Microbe!
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