Degradation enzymes from thermophiles are added as ingredients in hot-water detergents, increasing their effectiveness. Artificial fertilizers have become an important tool in food production around the world.
They are responsible for many of the gains of the so-called green revolution of the 20th century, which has allowed the planet to feed many of its more than 7 billion people.
Artificial fertilizers provide nitrogen and phosphorus, key limiting nutrients, to crop plants, removing the normal barriers that would otherwise limit the rate of growth. Thus, fertilized crops grow much faster, and farms that use fertilizer produce higher crop yields.
However, careless use and overuse of artificial fertilizers have been demonstrated to have significant negative impacts on aquatic ecosystems, both freshwater and marine. Fertilizers that are applied at inappropriate times or in too-large quantities allow nitrogen and phosphorus compounds to escape use by crop plants and enter drainage systems. Inappropriate use of fertilizers in residential settings can also contribute to nutrient loads, which find their way to lakes and coastal marine ecosystems.
As water warms and nutrients are plentiful, microscopic algae bloom, often changing the color of the water because of the high cell density. Most algal blooms are not directly harmful to humans or wildlife; however, they can cause harm indirectly. As the algal population expands and then dies, it provides a large increase in organic matter to the bacteria that live in deep water. Figure 3. Heavy rains cause runoff of fertilizers into Lake Erie, triggering extensive algal blooms, which can be observed along the shoreline.
Notice the brown unplanted and green planted agricultural land on the shore. Depletion of oxygen in the water is not the only damaging consequence of some algal blooms. The algae that produce red tides in the Gulf of Mexico, Karenia brevis , secrete potent toxins that can kill fish and other organisms and also accumulate in shellfish. Consumption of contaminated shellfish can cause severe neurological and gastrointestinal symptoms in humans. Shellfish beds must be regularly monitored for the presence of the toxins, and harvests are often shut down when it is present, incurring economic costs to the fishery.
Cyanobacteria, which can form blooms in marine and freshwater ecosystems, produce toxins called microcystins , which can cause allergic reactions and liver damage when ingested in drinking water or during swimming. Recurring cyanobacterial algal blooms in Lake Erie Figure 3 have forced municipalities to issue drinking water bans for days at a time because of unacceptable toxin levels.
This is just a small sampling of the negative consequences of algal blooms, red tides, and dead zones. Yet the benefits of crop fertilizer—the main cause of such blooms—are difficult to dispute.
There is no easy solution to this dilemma, as a ban on fertilizers is not politically or economically feasible. In lieu of this, we must advocate for responsible use and regulation in agricultural and residential contexts, as well as the restoration of wetlands, which can absorb excess fertilizers before they reach lakes and oceans. A soup container was forgotten in the refrigerator and shows contamination.
The contaminants are probably which of the following? Match the type of bacterium with its environment. Each choice may be used once, more than once, or not at all. Put the appropriate letter beside the environment. Can you make an educated guess as to its optimum temperature of growth?
Refer to Figure 2. Some hyperthermophiles can survive autoclaving temperatures. Are they a concern in health care? Skip to main content. Microbial Growth. Search for:. Temperature and Microbial Growth Learning Objectives Illustrate and briefly describe minimum, optimum, and maximum temperature requirements for growth Identify and describe different categories of microbes with temperature requirements for growth: psychrophile, psychrotrophs, mesophile, thermophile, hyperthermophile Give examples of microorganisms in each category of temperature tolerance.
Think about It What temperature requirements do most bacterial human pathogens have? Rachel Watson, M. AG Cell: rwatson uwyo. Temperature : Procedure The rates of chemical reactions in a cell are determined by the activities of its enzymes. These extremophiles are found in the Arctic, Antarctic and lakes fed by glaciers. Thermophiles can be found in hot springs, compost heaps, and hot water heaters. Extremophiles 1 : 14— Nat Rev Microbiol 17 : — Int J Syst Evol Microbiol 59 : — Appl Environ Microbiol 56 : — J Mol Evol 44 : — Bioresour Technol 89 : 17— Bioinformatics 20 : — Science : Nucleic Acids Res 33 : — Int J Syst Evol Microbiol 65 : — Appl Environ Microbiol 72 : 21— Appl Environ Microbiol 73 : — Geomicrobiol J 27 : — Environ Microbiol Rep 5 : — London: Prentice Hall.
PLoS One 13 : e In Encyclopedia of Life Sciences. Genome Biol Evol 5 : — Biophys J : — Bioinformatics 35 : — Nucleic Acids Res 37 : D5—D Microbiome 6 : Biochem Biophys Res Commun : — Int J Syst Evol Microbiol 53 : —
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