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Microorganisms: The Backbone of Life on Earth

  • Hand sanitizer and disinfecting wipes are now shelf staples for many retailers. Hands and homes are being sterilized with products promising to kill “up to 99.9 percent of germs.” The thought that a bacteria or virus could survive being napalmed is enough to send a shiver up your spine, especially in light of COVID-19. Disease-causing microorganisms are prevalent in the world, but it’s important to remember that most microorganisms are beneficial, even essential, for life on Earth.   

    The University of Florida’s online Graduate Certificate in Environmental Microbiology program explores the irreplaceable role microorganisms play as recyclers of essential nutrients. We thought we’d show our appreciation for these organisms by sharing how instrumental they are in shaping the world around us.  

    Here’s why microorganisms are the backbone of life on Earth.  

    What Are Microorganisms?   

    Microorganisms, or microbes, are organisms so small that they cannot be seen with the naked eye. They are generally single-celled living organisms, although some microbes, like viruses, cannot replicate on their own and are therefore not considered alive. This diverse group of organisms includes:   

    • Algae 
    • Bacteria 
    • Fungi  
    • Lichens  
    • Prions 
    • Protozoa 
    • Slime molds 

    Meet Your Ancestors  

    Microbes are the oldest forms of life on Earth, having evolved about 3.8 billion years ago. Until about one billion years ago, they were our planet’s sole inhabitants. During the Precambrian Era, asteroids and comets bombarded Earth, causing the seas to periodically boil over. For microbes to have survived, it’s thought that they had to have been thermophiles: organisms capable of surviving high temperatures. From the pollinating bee to the blooming orchid, all life on Earth evolved from these common ancestors.  

    Reuse, Recycle  

    The law of conservation of mass tells us that matter can neither be created nor destroyed. It can, however, undergo chemical and physical changes. Hydrogen, oxygen, carbon, nitrogen, sulfur and phosphorus are all necessary for supporting life. Yet in Earth’s closed system, these elements are finite and must be recycled. Microbes play an essential role in this process, breaking down and transforming decaying organic matter, or detritus, for their ecosystems.   

    The Nitrogen Cycle  

    Essential for cell functions, nitrogen can only be made available to plants, animals and other eukaryotes through nitrogen fixation. Nitrogen-fixing bacteria remove nitrogen from the atmosphere, while denitrifying bacteria return it to the atmosphere, completing the nitrogen cycle. Without microbes, nitrogen — one of the most essential elements for life on Earth — would become a catastrophically absent resource.    

    The Carbon Cycle  

    Plants are synonymous with photosynthesis. Yet microbes, specifically phytoplankton, are responsible for half of all photosynthesis. In fact, the majority of Earth’s oxygen comes from the ocean. Prochlorococcus, a species of bacteria, produces as much as 20% of the oxygen we breathe — more than all tropical rainforests combined. Phytoplankton are also the foundation of the aquatic food web. Floating beneath the ocean’s surface, these organisms convert sunlight into essential nutrients to support marine ecosystems and are themselves a food source for sea creatures, including zooplankton, shrimp and small fish.  

    On land, microorganisms convert carbon dioxide in the atmosphere into organic materials in a process known as carbon fixation. Microbial decomposers consume organic material from plants, animals and other microbes and, in the process, return carbon dioxide to the atmosphere. To our benefit, this cycle is unbalanced. Terrestrial ecosystems remove more carbon dioxide from the atmosphere than they return. How much carbon? It’s estimated that the amount of carbon stored in the Earth’s soil is three times that of carbon in the atmosphere.  

    Brown Food Webs  

    Most of us are familiar with “green” food webs, even if we don’t know them by that name. Energy stored in the organic molecules of plant leaves, stems and roots nourish prey animals, which nourish predators as energy flows upwards. However, the vast majority of plant matter — over 90% — is consumed as detritus. Animals also shed organic matter, expel waste and leave remains that become detritus. Detritus is the foundation of “brown” or “undead” food webs, where it is consumed by microbes and converted into nutrients plants rely upon. Brown and green food webs are all part of a single system through which energy flows. All species, including humans, are supported by decaying matter and microbial decomposers.  

    It’s Their World. We Just Live in It.  

    Human skin is awash with millions of bacteria, fungi and viruses, and our guts are home to trillions of bacteria. Indeed, the human microbiome — the collective name for the ecosystem of organisms that live on or within our bodiesis immense. Less than 1% of bacteria can cause illness, so consider microbes to be mostly harmless: at times deadly, but largely benign and beneficial. Their ability to spread disease pales in comparison to the important roles they perform in their ecosystems. Microbes, for better or worse, are the shepherds of life on Earth. We think it’s for the better.   

    Professionals who understand and appreciate the hidden world of microbes are in high demand. UF’s online Graduate Certificate in Environmental Microbiology is the only certificate program in the world that explores how microbes can be harnessed to solve real-world problems, such as climate change. Entirely online, our program provides the convenient, comprehensive instruction needed for individuals to excel in the field of environmental microbiology.  

    If you’re interested in learning more about microscopic organisms and their influence on the world around us, apply to our online Graduate Certificate in Environmental Microbiology 

    Want to explore the microbiome, the critical ecosystem of life that inhabits the human body and plays a critical role in our health? Learn more about our 12-credit Microbiome and Health Online Certificate program now. 





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