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Bacteria and Environmental Conditions Patricia Sidelsky Microbiology 156- Class 10 Energy for the Cell The energy currency of the cell is ATP ATP is adenosine tri phosphate Adenosine tri phosphate is used by the cell for the completion of all cellular process that have energy requirements Oxygen Aerobic bacteria – Do oxidative phosphorylation( production of ATP) Tolerate oxygen in the environment Have mechanisms for tolerating an oxygen rich environment Energy pathways- with oxygen Sugars and other molecules are broken down into intermediate molecules Glucose may be broken down into pyruvic acid 2C fragment from pyruvic acid( Acetyl COA) is fed into Kreb’s Cycle and Electron transport chain to produce ATP Anaerobic pathways Use alternate sources of electrons and hydrogen Oxygen is a poison No tolerance of oxygen in the environment Break down sugars into smaller carbon fragments and generally carry out a type of fermentation Terminology Aerobe – An organism that can grow in oxygen Obligate aerobe- An organism that requires oxygen as the terminal electron acceptor in the electron transport chain Anaerobe – Cannot grow in the presence of oxygen Aerotolerant – Like Enterococcus – oxygen is not a factor in the growth of these organiss Capnophile – Likes high levels of carbon dioxide Facultative anaerobe – Do not require oxygen but grow better in its presence Microaerophile – prefers levels of oxygen below 10% Free radicals Aerobic bacteria make free radicals during aerobic respiration Free radicals can be damaging to the cell The aerobic bacteria have the capacity to break down the free radicals Obligate aerobes make catalase or superoxide dismutase that breaks down free radicals Halophiles Grow in the presence of NaCl or other salts at levels greater than 0.2M These organisms have adjusted their membranes and metabolism to a hypertonic environment Their proteins and biochemistry have also adapted to this environment Halotolerant These orgnisms can tolerate lower levels of salt They are osmotolerant and can adapt to a varying level of salt in their environment by accumulating potassium inside of their cells pH pH is a measure of the hydrogen ion activity of a solution The pH scale extends from 0-14 0-7 is the acidic side of the scale 7-14 is the basic side of the scale 7 is neutral Acidophiles Prefer an environment of 0-5.5 The lower the number the more acidic the pH Neutrophiles Have a pH preference for levels between 5.5 and 8 Many pathogens fall in this group Bacteria that can adapt to varying levels of pH are many of the enteric pathogens E. coli and Salmonella have adapt by altering the proton pumps and other mechanisms for the movement of ions and molecules across their membrane Waste products Some bacteria give off waste by products that alter the environment and therefore adjust their environment Fermentative microbes produce acids which in fact change their environment in the small intestine and large intestine Alkalophiles Alkalophiles prefer environments with high pH. This environment is basic or alkaline Temperature preferences( cold) Psychrophiles – Live on the ice in Anarctica These organisms can survive extreme conditions and even grow in the cold Psychrotrophs – Live and grow in the refrigerator. These organisms can grow at temperatures of 7oC, but optimally can grow at temperature up to 30oC Mesophiles Prefer temperatures 25-40oC Human pathogens are mesophiles because human body temperatures fall within this range Thermophiles These organisms can grow at temperatures higher than 55oC The may be found in compost heaps or piles of hay They may also be found in hot water lines Their proteins have more stable structures at higher temperature Hyperthermophiles These microbes can survive in boiling water They can be found in the geysers of Yellowstone Part They tolerate these high temperatures New Work - Table Plate bacteria on different pH concentrations, acidic, neutral, and alkaline. Place in the holder Plate bacteria. Place in incubators at varying temperature levels Plate bacteria. Place one set in incubator( oxygen) Plate bacteria. Place the set in the anaerobic container and incubate.