Microbiology Chapter 27
Define extremophile, and identify two "extreme" habitats.
Microbes that live in extreme conditions like temperature, acidity, alkanity, or salinity.
Why are petroleum products naturally resistant to metabolism by most bacteria?
Microbes usually obtain their nutrients in an aqueous solution.
List some of the biochemical activities that take place in an anaerobic sludge digester.
Microbial activity occurs anaerobically. Methane is derived form the energy-yielding reduction of CO2 and H2.
Describe how pathogens are removed from drinking water.
They are removed from drinking water by boiling the water. They can also use chlorination, and filtration methods.
Outline the carbon cycle, and explain the roles of microorganisms in this cycle.
- photoautotrophs fix CO2 into organic matter using energy from sunlight. - Chemoheterotrophs eat autotrophs and may in turn be eaten by other animals. This makes the CO2 transfer from organism to organism up the food chain. -Chemoheterotrophs release the energy through respiration to start the cycle over again. -Leftover carbon and organic molecules in the organism will be decomposed by bacteria and fungi. Organic compounds are oxidized and CO2 is returned to the cycle.
Outline the nitrogen cycle, and explain the roles of microorganisms in this cycle.
-microorganisms decompose proteins from dead cells and release amino acids - ammonia is liberated by microbial ammonification of the amino acids -the nitrogen is ammonia oxidized to produce nitrates to molecular nitrogen -nitrogen is converted into ammonia by nitrogen-fixing bacteria - nitrogen-fixing bacteria include free-living genera such as Azotobacter, cyanobacteria and the symbiotic bacteria Rhizobium and Frankia - Ammonium and nitrate are used by bacteria and plants to synthesize amino acids that are assembled into proteins
Define symbiosis.
A close association between two unlike organisms that is beneficial to one or both of them.
Describe how an ecological community can exist without light.
An ecological community can exist without light by exploiting the energy in H2S. These communities can be seen in deep-sea vents, and deep caves. The primary producers are chemoautotrophic bacteria instead of photoautotrophic plants/microbes.
Why does phosphorus tend to accumulate in the seas?
Because there is no volatile phosphorus containing product to return phosphorus to the atmosphere.
Define biochemical oxygen demand (BOD), activated sludge system, trickling filter, septic tank, and oxidation pond.
Biochemical Oxygen Demand- a measure of the biologically degradable organic matter in water. Activated Sludge System- air or pure oxygen is passed through the effluent from primary treatment. 75-95% of the BOD removed. Trickling filters- the sewage is sprayed over a bed of rocks or molded plastic and a biofilm is formed and remove 80-5% of the BOD. Septic Tank- a device whose operation is similar in principle to primary treatment. Oxidation ponds- inexpensive when the first stage mimics primary treatment and the second stage, it is pumped into a pond to be aerated.
How do flocculants such as alum remove colloidal impurities, including microorganisms, from water?
By adding a chemical that causes colloidal particles to coalesce, or become one mass.
Define biogeochemical cycle.
Carbon, nitrogen, and sulfur are oxidized and reduced by microorganisms to meet their metabolic needs. Without the cycles, life on Earth would not exist.
Compare and contrast the carbon cycle and the phosphorus cycle.
Carbon: All organisms, including plants. microbes, and animals, contain large amounts of carbon in the form of organic compounds as cellulose, starches, fats, and proteins. Phosphorus: May determine whether plants and other organisms can grow in an area. The cycle instead involve changes from soluble to insoluble forms and from organic to inorganic phosphate, often in relation to pH.
Discuss the causes and effects of eutrophication.
Causes include phosphates pass nearly unchanged through sewage systems. Effects include the removal of oxygen from a body of water which can be disastrous to the biome. Can also harm humans if they ingest the water or any sea animal they might eat.
Bacteria of the genus Pseudomonas, in the absence of oxygen, will use fully oxidized nitrogen as an electron acceptor, a process in the nitrogen cycle that is given what name?
Denitrification.
Describe the freshwater and seawater habitats of microorganisms.
Freshwater- microbial populations of freshwater bodies tend to be affected mainly by the availability of oxygen and light. There are four zones, littoral, limnetic, profundal, and benthic zone. Seawater- Seafloor sediments have large populations of organisms which are mostly Archaea. They make immense amounts of CH4. Towards the sunlit water there are many photosynthetic cyanobacteria.
What chemical usually serves as an energy source for organisms that survive in darkness?
H2S
Certain nonphotosynthetic bacteria accumulate granules of sulfur within the cell; are the bacteria using hydrogen sulfide or sulfates as an energy source?
Hydrogen sulfide.
Explain how wastewater pollution is a public health problem and an ecological problem.
If wastewater pollution is ingested by humans, then they may get severely sick and could die. Ecologically wastewater pollution can lead to eutrophication.
Define mycorrhiza, differentiate endomycorrhizae from ectomycorrhizae, and give an example of each.
Mycorrhiza- an important symbiosis relationship betwee plant roots and certain fungi. Endomycorrhizae exchange mechianism on the inside of the root cell like grasses while Ectomycorrhizae exchange mechanisms outside of the root cell like truffles.
Define ammonification, nitrification, denitrification, and nitrogen fixation.
Nitrogen fixation- nitrogen is taken up and combined into organic compounds. Converting nitrogen gas to ammonia. Ammonification- the release of ammonia brought about by numerous bacteria and fungi. Nitrification- the oxidation of the nitrogen in the ammonium ion to produce nitrate. This is possible with autotrophic nitrifying bacteria. Denitrification- can lead to a loss of nitrogen to the atmosphere, especially as nitrogen gas.
Compare primary, secondary, and tertiary sewage treatment.
Primary- large floating materials in incoming wastewater are screened out. Sometimes chemicals are added. 40-60% of the sludge is removed. Secondary- Most of the BOD is in the form of dissolved organic matter. Most of this organic matter is removed during this treatment and the BOD is lowered. Tertiary- practiced in now arid-area cities. Sewage can be treated to a level of purity that allows its use as drinking water. Removes all the BOD, Nitrogen, and Phosphorus.
What is the common name for the group of microbes that oxidize soil nitrogen into a form that is mobile in soil and likely to be used by plants for nutrition?
Symbiotic nitrogen fixing bacteria.
Outline the sulfur cycle, and explain the roles of microorganisms in this cycle
The sulfur cycle is very similar to the nitrogen cycle. -hydrogen sulfide (H2S) is used by autotrophic bacteria; the sulfur is oxidized to form S0 or SO4^-2 -plants and other microorganisms can reduce SO4^2 to make certain amino acids. these amino acids in turn used by animals -H2S is released by decay or dissimilation of these amino acids
Define bioremediation.
The use of microbes to detoxify or degrade pollutants.
Purple and green sulfur bacteria are photosynthetic organisms, but they are generally found deep in freshwater rather than at the surface. Why?
They are anaerobic to photosynthetic organisms that metabolize H2S to sulfur and sulfate in the bottom sediments of the benthic zone.
Explain how water is tested for bacteriological purity.
Water is tested for purity today are aimed to detect particular indicator organisms. Presence of these indicates fecal contamination of food or water.
What metabolic group of anaerobic bacteria is especially encouraged by operation of a sludge digestion system?
anaerobic and facultatively anaerobic fermentation
Give two examples of the use of bacteria to remove pollutants.
free-living Nitrogen-Fixing bacteria, Symbiotic Nitrogen-Fixing Bacteria