4 Ways Tiny Microbes Changed Life on Earth Forever
Shilpa Malakar, M. Sc.
PG at Kalinga University, Raipur | Ex FRI-Dehradun Environmental Science Trainee and Former-Intern at BioLim Centre for Science & Technology (BCST) - Chennai || Microbiologist || Bacteriologist || Aspiring Researcher.
This is the microbes' world—we just live in it. Throughout the history of Earth, microbes have radically reshaped life on the planet, from creating the very air we breath to wiping out almost all life on Earth. Don't underestimate the power of tiny, tiny microbes populating the Earth trillions of times over.
Here are some of the ways microbes have done what humans are doing now: geoengineering the climate.
How the Earth's Atmosphere Got Oxygen
Among the complications of traveling 3 billion years back in time is the fact that you would immediately suffocate. There wasn't much oxygen, if any, in Earth's atmosphere back then. But about 2.7 or 2.8 billion years ago, cyanobacteria—also known as blue-green algae—began to proliferate for reasons still unclear. Like their descendants today, these cyanobacteria could turn sunlight, water, and carbon dioxide into carbohydrates and oxygen. You might recognize this process as photosynthesis.
The oxygen in Earth's atmosphere increased rapidly—for a geologic time scale, anyway—reaching the 21 percent we breathe today. The Great Oxygenation Event had a profound impact on Earth's life. Oxygen is highly reactive, which means it messes up the metabolism of microbes unused to living in an oxygenated atmosphere. Those microbes, called anaerobes, once dominated the Earth but now live deep underground or underwater where oxygen is still scarce. On the flip side, oxygen's reactivity could also be harnessed for metabolism, making possible the very existence of energy-hungry, multicellular organisms like us. Complex animals could not exist if not for these cyanobacteria.
Geologists know about the Great Oxygenation Event because of the sudden appearance of iron oxides—basically forms of rust—over two billion years ago in the Earth's crust. Collectively, these tiny cyanobacteria made their mark on Earth, shaping both the planet's animate and inanimate forms.
The Worst Mass Extinction in the History of the Earth
250 million years ago, Earth went through the Great Dying. Temperatures rose, the oceans acidified, and ninety percent of all species were wiped off the face of the planet. One of the more prominent explanations for the Permian-Triassic Extinction is a burst of volcanic activity in the Siberian Traps of modern-day Russia. A?recent study?fingers an additional culprit: a bloom in methane-belching microbes called?Methanosarcina.
According to this study,?Methanosarcina?simply acquired two genes?from an unrelated bacterium?about 250 million years ago. These genes let the microbes feed on a previously untapped food source: a carbon compound called acetate abundant in ocean sediments. Feed and grow they did, all the while releasing vast amounts of methane, a greenhouse gas, that warmed the atmosphere and acidified the oceans. Volcanoes could have still played in a role in spewing out nickel, which is necessary for the chemical reaction that lets microbes make methane gas. The abundance of nickel would have eased along the microbe's runaway growth—and decimation of the rest life on Earth.
Nitrogen-Fixing Microbes and Our Food
In 1910, the German chemist Fritz Haber invented a process to mimic what microbes had been already doing for millions of years: fix nitrogen from the atmosphere into ammonia. While all life on Earth requires nitrogen, the inert nitrogen gas that makes up 78 percent of the planet's atmosphere is useless to all but some nitrogen-fixing bacteria. The Haber process changed that. With a?new source of nitrogen fertilizer, agriculture exploded and the human population more than quadrupled in that time. It's estimated that?half of the nitrogen?in all our bodies originated with the Haber process.
While Haber's invention enabled a human population boom in the past century, it's nitrogen-fixing microbes that sustained all life before it. (And, remember, the other half of nitrogen in our bodies still originated with these microbes.) The microbes that fix atmospheric nitrogen gas are called diazotrophs. They're a diverse group that inhabit nearly every ecosystem on the planet, from the soil to coral reefs to lichen. In a way, they're at the bottom of every food chain.
The most famous of diazotrophs might be Rhizobia, bacteria that live inside the root nodules of legumes such as clovers, peanuts, and alfalfa. These plants feed sugars to the bacteria in exchange for nitrogen. The fixed nitrogen stays in the soil even after the plant dies, which is why farmers plant cover crops like clover and alfalfa in between seasons. As overuse of nitrogen fertilizers has wrought its own problems—like run-off that causes algae blooms—we might better appreciate role of these nitrogen-fixing bacteria.
What Microbes Mean For Climate Change
In July of 2012, 100 tons of iron filing were dumped off the coast of Canada in the?world's largest geoengineering experiment—and an entirely unauthorized one at that. The American businessman Russ George was trying to prove a bizarre sounding idea to combat climate change: ocean fertilization.
In theory, phytoplankton would capitalize on this sudden iron bonanza, growing like crazy and pulling in carbon dioxide from the atmosphere. While George's unauthorized experiment was soundly rebuked by the international community, the role of microbes in climate change is coming under increasing scrutiny.
Microbes can both absorb or release carbon, depending on their diets, so the direction of their influence is not so clear. But, in aggregate, they are huge players in the carbon cycle. Just the microbes that decompose dead plants in the soil, for example, release 55 billion tons of carbon dioxide a year, which is eight times what humans contribute through fossil fuels and deforestation.
And climate change is changing how these microbes function. In the cold Siberian tundra, for instance, there is normally not much microbial activity. In recent years, however, the tundra is releasing more carbon dioxide than it absorbs, which scientists believe is due to rising temperatures allowing more microbes to feed in the tundra and release carbon dioxide. The same could be happening in the oceans.
You might say microbes were the original "geoengineers" of the Earth, leaving a profound influence on the planet's climate and the lifeforms. As we begin to understand Earth's microbial world, geoengineers are also looking at how to harness the awesome power of these tiny microbes. Small changes in aggregate trillions of times over can entirely reshape life on Earth. [Nature News,?Scientific American,?Yale Environment 360]
Your Microbes and You
The Good, Bad and Ugly
Microscopic creatures—including bacteria, fungi and viruses—can make you ill. But what you may not realize is that trillions of microbes are living in and on your body right now. Most don’t harm you at all. In fact, they help you digest food, protect against infection and even maintain your reproductive health. We tend to focus on destroying bad microbes. But taking care of good ones may be even more important.
You might be surprised to learn that your microbes actually outnumber your own cells by 10 to 1. “The current estimate is that humans have 10 trillion human cells and about 100 trillion bacterial cells,” says Dr. Martin J. Blaser at the New York University School of Medicine. New techniques allow scientists to study these rich microbial communities and their genes—the “microbiome.” In 2007, NIH launched the Human Microbiome Project to study microbes in and on the body.
Earlier this year, researchers from almost 80 institutions published a landmark series of reports. They found that more than 10,000 different species occupy the human body. The microbiome actually provides more genes that contribute to human survival than the human genome itself (8 million vs. 22,000). Humans need bacteria and their genes more than most of us thought.
One of the most important things microbes do for us is to help with digestion. The mix of microbes in your gut can affect how well you use and store energy from food. In laboratory experiments, transferring bacteria from certain obese mice to normal ones led to increased fat in the normal mice.
Blaser and his colleagues are concerned that changes in our microbiome early in life may contribute to weight problems later. “We’re in the middle of an epidemic of obesity that is very severe,” Blaser says. “It’s relatively recent, it’s widespread across the United States and across the world, and increased calories and decreased exercise seem insufficient to explain this.”
We might be changing our microbiome for the worse, he says, by using antibiotics too often. In a recent NIH-funded study, Blaser’s team found that low-dose antibiotic therapy affected the gut microbiomes of young mice. Antibiotics also altered how the mice used sugars and fats. After 7 weeks, treated mice had up to 15% more fat than untreated mice. This and other studies suggest that gut bacteria can affect both appetite and how you use energy in food.
In related work, Dr. Leonardo Trasande, Blaser and colleagues analyzed data from more than 11,000 children. Although the results weren’t conclusive, they suggest that infants given antibiotics might be at increased risk of becoming overweight. More work will be needed to confirm this connection.
“Microbes in our intestines may play critical roles in how we absorb calories,” Trasande says. “Exposure to antibiotics, especially early in life, may kill off healthy bacteria that influence how we absorb nutrients into our bodies, and would otherwise keep us lean.”
Microbes are also important for your skin, one of the body’s first lines of defense against illness and injury. Skin health depends on the delicate balance between your own cells and the microbes that live on its surface.
“Basically, the healthy bacteria are filling all those little niches so that the more dangerous bacteria can’t get a foothold onto the skin,” says Dr. Julie Segre of NIH. Segre and other NIH researchers looked at skin microbes collected from different body regions on healthy volunteers. They found that body location has a huge effect on which types of bacteria live. For example, bacteria living under your arms likely are more similar to those under another person’s arm than to the bacteria on your own forearm.
Microbes are also important to the body’s infection-fighting immune system. In one recent study, NIH scientists examined special mice that were born and raised to be germ-free.
These mice seemed to have weak immune function. In contrast, normal mice have vibrant bacterial communities and a rich variety of immune cells and molecules on their skin.
The germ-free mice were exposed to?Staphylococcus epidermidis, one of the most common bacteria on human skin. Adding this one species of bacteria boosted immune function in the mouse skin. The mice with?S. epidermidis?were able to defend against a parasite, whereas the bacteria-free mice weren’t.
“We often have a sense that the bacteria that live on our skin are harmful,” Segre says. “But in this study we show that these bacteria can play an important role in promoting health by preventing skin infections from becoming more prolonged, pronounced and more serious.”
There’s strong evidence that the microbes in the female reproductive tract affect reproductive health and help protect against disease. A recent study also found a diverse community of microbes in the male urinary tract and on the penis. NIH-funded researchers are investigating other positive roles for microbes. One major area of research concerns allergy-related conditions, including childhood asthma, skin allergies, hay fever and eczema.
So what can you do to protect against microbes that cause infection but take care of the ones that help you? We know that washing our hands is important for removing harmful microbes—for example, before eating or after using the bathroom.
Other less obvious things can affect your skin microbes, Segre says. The lotions and creams you use can provide a barrier to protect your skin’s moisture, Segre points out, “but in fact you’re also putting a fertilizer onto the microbial garden. You’re really changing the food source for the bacteria that live on your skin.” There’s not one right answer about which skin products are best for you, she says. Experiment to see how different ones affect your skin.
Many researchers worry that some people are trying to get too clean. Blaser thinks that people are using sanitizers and antibiotic products too often these days. “Obviously, there are many bad germs, but I think we’ve gone overboard and it looks like trying to get rid of the bad guys has had a collateral effect on the good guys.”
You’re never alone when it comes to your microbes. But don’t get squeamish about it. Just remember how much you need them.
Microbes & Humans
Many people think of bacteria, viruses, and other microorganisms as our enemy.?This perspective, called the germ theory of disease, was first proposed in the 19th century. It maintained that illness springs from the actions of infecting microorganisms, drawing battle lines between “us” (the afflicted?hosts) and “them” (the invading microbes). Germ theory was crucial in identifying many diseases caused by microbes and in finding ways to prevent them through measures such as?immunization, sanitation, and improved living conditions. By the mid-1960s many experts concluded that infectious disease was all but conquered and researchers could shift their focus to?chronic?medical conditions such as heart disease and cancer.
Today, many scientists recognize the need for a more ecological view of the microbial world around us: Microbes and their hosts (including humans) ultimately depend on each other for survival.
But this optimism was shaken in the mid-1970s and early 1980s with the appearance of?Lyme disease, Legionnaires’ disease, toxic shock syndrome, and human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). It was dealt further blows with the development of?antibiotic-resistant?bacteria and the appearance and spread of severe acute respiratory syndrome (SARS), H1N1, Middle East respiratory syndrome coronavirus (MERS-CoV), and?Ebola. Scientists began to re-examine the relationship between hosts and microbes.
Today, many scientists recognize the need for a more?ecological?view of the microbial world around us: Microbes and their hosts (including humans) ultimately depend on each other for survival. And although the microorganisms that cause disease often receive more attention, most microorganisms do not cause illness. In fact, many of them protect us, helping our bodies function properly and competing with harmful organisms in an ongoing contest for habitable space in and on our bodies.
There is a close connection between microbes and humans. Experts believe that about half of all human?DNA?originated from viruses that infected and embedded their nucleic acid in our ancestors’ egg and sperm cells. Microbes occupy all of our body surfaces, including the skin, gut, and?mucous membranes. In fact, our bodies contain at least 10 times more bacterial cells than human ones, blurring the line between where microbes end and humans begin. Microbes in the human?gastrointestinal tract?alone comprise at least 10 trillion organisms, representing more than 1,000 species, which are thought to prevent the gut from being colonized by disease-causing organisms. Among their other beneficial roles, microbes synthesize vitamins, break down food into absorbable nutrients, and stimulate our?immune system.
The vast majority of microbes establish themselves as persistent “colonists,” thriving in complex communities within and on our bodies. In many cases, the microbes derive benefits without harming us; in other cases, both host and microbe benefit. And though some microbes make us sick and even kill us, in the long run they have a shared interest in our survival. For these tiny inhabitants, a dead host is a dead end.
The success of microorganisms is due to their remarkable adaptability. Through natural selection, organisms that are genetically better suited to their surroundings have more offspring and transmit their desirable traits to future generations. This process operates far more rapidly in the microbial world than in people. Humans produce a new generation every 20 years or so; bacteria do it every 20 to 30 minutes, and viruses even faster. Because they reproduce so quickly, microorganisms can assemble in enormous numbers with great variety in their communities. If their environment suddenly changes, the community’s genetic variations make it more likely that some will survive. This gives microbes a huge advantage over humans when it comes to adapting for survival.
Most Lucrative Entry Level Biology Degree Jobs
#1?Microbiologist
Avg. Salary:?$69,960
Career Growth:?8%
Typical Education Level:?Bachelor’s degree
With nearly $70,000 a year in annual salary and only a bachelor’s degree and no prior experience required (generally), a microbiologist is a wonderful career path for any biology major. This career allows you to study some of the smallest lifeforms, including bacteria, algae, and fungus, and although much of the work is done in laboratories, you’ll likely have the chance for field work, such as collecting samples. A bachelor’s degree in biology, with a focus or minor in microbiology, sets you up to start this career. Microbiologists are employed by research institutions, medicine manufacturers, and government agencies, and the top 10% can expect a salary over $129,000.
#2?Environmental Scientist
Avg. Salary:?$69,400
Career Growth:?11%
Typical Education Level:?Bachelor’s degree
Environmental scientists conduct many different research projects and experiments, primarily focusing on how to protect the environment and enhance human and animal health. It’s a fascinating field that doesn’t require previous experience and only demands a bachelor’s degree. It also has an expected career growth of 11%, meaning it will grow faster than the average job market. You’ll not only be able to earn a sizable income immediately after college, you’ll land in a growing field with plenty of opportunities and have the potential to earn over $122,000 if you are in the top 10%.
GetEducated’s Pick
Southern New Hampshire University
#3?Agricultural & Food Scientist
Avg. Salary:?$62,910
Career Growth:?7%
Typical Education Level:?Bachelor’s degree
As the world’s population grows, more efficient and environmentally-friendly ways to produce food are needs. Much of this responsibility will fall on the shoulders of food scientists, who improve agricultural practices and products through scientific advancements. This career has no required work experience or on-the-job training, and brings an annual salary over $116,00 for the top 10%, making it one of the best entry level biology degree jobs.
GetEducated’s Pick
·?University of Maryland – University College?BS in Biotechnology
Highest Paying Jobs?in Biology
Now let’s look at the best jobs?for biology majors that have excellent, lifelong career potential coupled with?impressive salaries.
?Physician
领英推荐
?Average salary:?$208,000
One of the most respected, appreciated, and well-paid careers in the world, the role of a physician is vital to the overall health of people young and old. Thanks to a salary over $208,000, this is easily among the highest-paid jobs with a biology degree. However, landing this type of position takes years of experience, education, and training. If you make it through, you’ll have an excellent salary in a field that is expected to grow 13% by 2026.
Required Education:?Doctorate
Dentist
Average salary:?$158,120
Even the toughest people in the world can fear going to the dentist, but despite the fear, this profession remains crucial for overall health. The career is expected to grow by 19%, meaning there should be plenty of opportunities for dental students. While a doctorate in dentistry is required, a bachelor’s degree in biology is a great place to start your education, and you could earn over $208,000 if you are at the top 10% of the dental profession.
Required Education:?Doctorate
Podiatrist
Average salary:?$127,740
The health of your feet and ankles can have a profound effect on your overall comfort and wellbeing. Thanks to podiatrists, which are doctorate-level professionals with internship and residency requirements, people can have healthy feet and, hopefully, a healthy, active lifestyle. This career can start with an education in biology, and can result in an annual salary of over $127,000 a year while the top 10%?earn over $208,000. The work environment is usually offices and clinics, although some work in general-practice facilities, such as hospitals and care centers.
Required Education:?Doctorate
Pharmacist
Average salary:?$124,170
Pharmacy is all about dispensing specific medications to improve the health and wellbeing of patients. This field requires a doctorate in pharmacology or a related field, but it can start with a bachelor’s degree in biology. With an annual salary over $124,000 and annual earnings over $159,00 for the top 10%, it’s one of the best biology-degree jobs. Although the career growth is 6% (right around the national average), the profession is expected to add over 17,000 jobs by 2026, most of which will be employed in pharmacies, which can include facilities in drug stores, grocery stores, and pharmacies in health centers.
Required Education:?Doctorate
Optometrist
Average salary:?$110,300
Earning over $110,000 a year, and over $190,00 for the top 10%, optometrists examine the eyes and other parts of our anatomy that help us see clearly. These professionals, who need a doctorate in the field, diagnose and treat visual issues and often help people manage visual disorders or prescribe glasses. In this profession, you could work in a stand-alone clinic, although employment in a doctor’s office is possible. With an expected career growth of 18%, this is one of the many growing jobs with a biology degree.
Required Education:?Doctorate
Physician Assistant
Average salary:?$104,860
Despite only needing a master’s degree, a?physician’s assistant?can earn over $104,860 a year, and the top 10% will earn over $146,000, making this one of the high-paying jobs with biology degree. Physician assistants help the medical process by examining, diagnosing, and treating patients. They may prescribe medicine, assess records, and educate patients, and the career is expected to grow by a whopping 37%. While a medical education is required, a degree in biology creates a wonderful foundation for the schooling and the career.
Required Education:?Master’s Degree
Biochemist or Biophysicist
Average salary:?$91,190
These professionals hold an interesting and unique career that focuses on the chemical and physical foundations that make life possible. This can include cell development, the chemistry of disease, or the physiology of metabolism. The career will require a doctorate, but after it’s completed you could earn a salary over $91,000 year, and if you work you way to the top 10%, your earnings could top $177,000 annually. Many bachelor’s degrees can lead to this profession, including chemistry, physics, and (of course) biology.
Required Education:?Doctorate
Veterinarian
Average salary:?$90,420
Do you love animals? Do you want to learn about new and exciting techniques to treat patients of all kinds? Then perhaps a career as a veterinarian would be perfect for you. Veterinarians need to be versatile and well-rounded, so a bachelor’s in biology is the perfect start for this career. Although a doctorate is required, there are no requirements for work experience or on-the-job training. It is expected to grow rapidly, driven largely by increases in pet-related spending. The top 10% of this career can expect a salary over $159,000, making it one of the best jobs you can get with a biology degree as your educational foundation.
Required Education:?Doctorate
Medical Scientist
Average salary:?$82,090
Although physicians work directly with patients to improve care, they often rely on the work if medical scientists to improve their techniques and practices. Medical scientists use experiments and research to create new approaches to treatments and disease prevention. A doctorate is required, but these biology degree jobs can bring a salary over $160,000 for the top 10%. Working in offices and laboratories, much of a medical scientist’s job will involve studying data and reports. With no on-the-job training or experience requirements, this is a wonderful opportunity for medical-related professionals who may not wish to work directly with patients.
Required Education:?Doctorate
Biology Teacher
Average salary:?$76,000
Maybe you love biology and have a passion for teaching. In that case, a career as a?biology teacher?or professor at the collegiate level may be a good choice for you. You can start the path to this career with a bachelor’s degree in biology, and then move into a specialized master’s degree or even a doctorate. Among all postsecondary teachers, the average salary is over $76,000 per year, while the top 10% earn over $170,000. With the demand for college education expected to rise, the career opportunities for postsecondary teachers is expected to grow 15% between 2016 and 2026.
Required Education:?Master’s Degree
Registered Nurse (RN)
Average salary:?$70,000
As a fundamental part of the healthcare system,?registered nurses?help coordinate patient care and assist in the education of patients. As one of the professionals in direct contact with patients, they can also provide advice and emotional support. This career requires specific education and certification in nursing, but a bachelor’s degree in biology gives you a well-rounded knowledge of the human body, making you an even more effective RN. With a top pay over $104,000 for the top 10%, it’s also a lucrative career path.
Required Education:?Bachelor’s Degree
Wildlife Biologist
Average salary:?$62,290
These professionals study animals and their interaction with ecosystems, providing useful information on animal behavior, human impact, and the characteristics of wildlife. In this job, you could work in an office, a lab, in the field, or all three in a single day. Fieldwork can include travel to unique destinations, making it one of the most interesting and exciting jobs with a biology degree. It will bring a great salary with only a bachelor’s degree and no required experience, and the top 10% can expect a pay over $99,000 a year.
Required Education:?Bachelor’s Degree
Archeologist
Average salary:?$62,280
An archaeologist is dedicated to investigating and preserving the clues of former cultures and lifeforms, which provide a unique insight into our past, as well as perspective on our own times. They may investigate prehistoric sites, and use a wide range of knowledge, including biology, to interpret findings. These professionals need a master’s degree, but a bachelor’s in biology gives them a great start. Although the career field is only expected to grow by 4%, the top 10% in the profession can expect an annual salary over $99,000.
Required Education:?Master’s Degree
Writer
Average salary:?$61,820
Without a biology education and a fundamental understanding of science, author Micheal Crichton (bachelor’s in biological anthropology) may have never written the now world-famous novel Jurassic Park or created the hit show ER. While being a fiction author may not seem like the role of a biology student, if you want to write, and have a passion for both science and story-telling, perhaps you could, like Crichton, become a science author and writer. This degree will give you the skills needed to analyze information, research topics, and turn biological science into books, television shows, news articles, and (just maybe) blockbuster movies.
Required Education:?Bachelor’s Degree
Conservation Scientist
Average salary:?$60,970
These professionals study and manage overall land quality in many different areas, including forests, parks, and rangelands. They may also be responsible for overseeing natural resources. A bachelor’s degree in forestry is often the path for this career, but specializing or minoring in general biology could also lead to this profession. Most people in this career get to spend time outside, although time is often split between field work and office and lab study. With only a bachelor’s degree, this career can bring an average salary over $97,000 for the top 10%.
Required Education:?Bachelor’s Degree
Perhaps you have a degree in biology, but aren’t sure if working in a science- or biology-related field is the right choice for you. In this case, you may need to sell your skills and experiences to employers who have little concern for the interplay of animal species or the interworking of the human body. Fortunately, you can still sell your useful skills to many employers.
During interviews, it’s important to focus on many of the specific projects you worked on, citing examples of problem-solving, leadership, group work, or any other skills that could apply to the career. Discuss your understanding of research, data analysis, and other skills that made you a successful biology student and you’ll be more attractive to more clients.
After you complete a biology degree, you really have two options. First, you can go into one of the entry-level biology-degree jobs, such as microbiology or wildlife biologist. Or you can continue your education and expand your knowledge of biology by earning a master’s and, eventually, your doctorate.
With a base degree in biology, you can move into a master’s degree in a specialized field that suits your specific interest. If you are interested in zoology, for example, you could seek a master’s degree that focuses on animal biology; if you are interested in the environment, a master’s in environmental biology or a related field may be a great choice.
Helping You Become a Success in Any Field
With comprehensive, unbiased resources and a large inventory of college rankings, GetEducated is the leader in helping education consumers chose the best?school for your goals!
?
?