*swii*

How Microbes Make Fermented Food

Just like any form of life, microbes need energy. To get it, they consume molecules they come into contact with for sustenance. No metabolism is perfect, though, and even the smallest meals produce waste products, a process known as fermentation. A microbe’s trash can be a treasure to us, though—these waste molecules are key ingredients in the fermented foods and drinks that are cornerstones of cuisine around the world.

Fermentation works by feeding sugars to microbes like yeast, a fungus, or a bacteria such as Lactobacillus. The two types of microbes have different means of processing the carbohydrates they dine on. For bacteria, the end product of fermenting sugar is a simple molecule called lactic acid, a weak acid with a rather sour taste. Yeast, one the other hand, produces a molecule called ethanol, the inebriating agent in alcohol. Humans figured out early on that both of these waste products could create tasty dishes while also helping food keep longer, as demonstrated in the three recipes below.

Pickling

Fermenting vegetable matter with bacteria (specifically strains of Lactobacillus) produces sour-flavored, long-lasting treats. Better known as “pickling,” this process is used in cuisines all around the world to crafts foods from kosher dills to kimchi. The process is thought to have originated thousands of years ago in Egyptian society. 

Beer

Fermenting grains or fruits with yeast is a tradition at least as old as pickling, and one that’s also known around the world. Luckily for folks who enjoy a beer or glass of wine with dinner, yeast converts sugars into alcohol instead of lactic acid. While the two substances have similar chemical formulas (lactic acid consists of  six hydrogen molecules, teamed with three carbon and three oxygen atoms, while alcohol binds six hydrogen atoms to a pair of carbon atoms and a single oxygen atom) they do very different things when they come in contact with our bodies and communicate with our brains—hence the difference between sour-tasting pickles and inebriating beer.

Sourdough Bread

But what happens when a concoction combines Lactobacillusand yeast? Sourdough bread is a good example of this forced symbiosis. Bakers have taken advantage of a wide array ofLactobacillus species and their close relatives to produce three kinds of sourdough bread. The lactic acid from the bacteria and carbon dioxide produced by the fermentation of yeast give this bread its distinctive tangy taste and fluffy texture. The fermentation process also converts the linoleic acid in bread flour into fatty acids that resist the growth of mold and help the loaf stay edible longer, a quality that made this food a favorite among gold surveyors in California. In addition, the presence of yeast means that sourdough freshly out of the oven will have some alcohol in it, although this content evaporates as time goes by.

Learn more about microbes in the new exhibition, The Secret World Inside You, now open! 

Images: AMNH/M.Fearon

Are microbes dangerous?

Not as dangerous as we used to think.

The grand majority of microbes are either not in contact with us or, if they are in contact with us, they’re actually mutualistic, which means that we gain a benefit from them, they gain a benefit from us. Or they’re simply neutral.

They’re dangerous when we make them dangerous. We make them dangerous through antibiotic overuse. Antibiotics change the makeup of the microbial ecology in the gut, especially, and that change in microbial makeup triggers a bunch of secondary reactions and interactions.

Learn more with the ABC’s of microbes. 

Be Thankful For Your Microbiome

Happy Thanksgiving from the American Museum of Natural History! This year, we’re thankful for our microbiome, which is particularly helpful in digesting the traditional holiday feast many of us will be enjoying today. 

Millions of microbes enter your body at every meal. Indeed, after your skin, the digestive system is the main place where your body comes in contact with microbes. But unlike your skin, your digestive system is a warm, sheltered space—and it’s filled with food. It’s the perfect spot for microbes. So it’s no surprise that the vast majority of your body’s microbiome is inside your digestive tract. Your digestive tract is home to around 100 trillion bacteria—more than all the stars in the Milky Way galaxy. Many fibers from food, including cellulose, cannot be digested by the human body alone—but resident bacteria produce enzymes that can break them down. 

Stomach
Almost no nutrients are absorbed in the stomach. It is filled with harsh acids that kill most bacteria. Very few live here permanently.

Small intestine
Your small intestine is about 20 feet (6 meters) long. Most of your food is digested in your small intestine. Sugar, fat and protein are broken down and absorbed, with the help bacteria.

Large intestine
Your large intestine is where fibers ferment, frequently for 40 hours. Trillions of microbes ferment fiber and other food you can’t digest, producing useful nutrients and protecting your gut lining from inflammation.

MY GUT? SO WHAT?
Microbes in your gut play many important roles in your body. They help with digestion, immune regulation, disease prevention, healing and protecting your gut lining, appetite control, brain development and even emotion.

Learn more about your microbiome in The Secret World Inside You, now open at the Museum!

Happy Friends Day! Approximately 100 trillion friends are much closer than you think…all over your body. 

Your body is an ecosystem of microbes, composed of 10,000 different species. Genetically we get even less real estate: 99 percent of the unique genes in our bodies are bacterial. This population of microorganisms has evolved along with homo sapiens to help orchestrate basic life processes, beginning the moment we’re born.

Meet some of these friendly microbes:

Learn more in the new exhibition, The Secret World Inside You.

Discoveries by scientists like Antonie van Leeuwenhoek and Robert Koch connected microbes to infectious disease. These discoveries formed a way of thinking called “germ theory” that said a specific microbe caused a specific disease. With widespread use of antibiotics beginning in the 1940s, people zealously tried to rid their lives of any and all microbes, spreading the anti-microbial mindset to personal and household cleaning.

But today, scientists are starting to reevaluate germ theory. Using antibiotics to treat bad germs will remain an essential, life-saving part of medicine. But repeated or unnecessary use of antibiotics prevents our bodies from establishing the community of microbes it needs. Scientists now suggest that we look at microbes in context, understanding that microbes (Helicobacter pylori, for example) can be both beneficial and harmful

Overusing antibiotics has pushed microbes to evolve resistance, making them less available for general health care or surgical procedures. Clostridium difficile (pictured) is an example of a strongly antibiotic-resistant microbe. Successful treatment of C. diff. happens when a patient’s gut community comes back into balance, often by introducing a new microbial community from the stool of a healthy donor.

Learn much more about this topic in the Museum’s newest exhibition, The Secret World Inside You, now open. 

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Read the The New York Times review of the new Museum exhibition, the Secret World Inside You:

“Unlike virtually every exhibition at the museum, “The Secret World Inside You” offers no specimens in glass cases. It speaks of a world invisible to the naked eye, so getting the big messages across calls for ingenuity. The exhibition team, rising to the challenge, has come up with highly entertaining teaching games, quizzes, whiz-bang animation and compelling visual effects. Children and their parents can both have a good time — and learn a lot." 

Read the full review.

Get tickets now for the Secret World Inside You, opening November 7. 

How do you make a Thanksgiving meal? Turkey, gravy, cranberries and mashed potatoes may all come to mind, but what about microbes? Microbes help make many of our favorite holiday dishes!

Just like any form of life, microbes need energy. To get it, they consume molecules they come into contact with for sustenance. No metabolism is perfect, though, and even the smallest meals produce waste products, a process known as fermentation. A microbe’s trash can be a treasure to us, though—these waste molecules are key ingredients in the fermented foods and drinks that are cornerstones of cuisine around the world.

Fermentation works by feeding sugars to microbes like yeast, a fungus, or a bacteria such as Lactobacillus. The two types of microbes have different means of processing the carbohydrates they dine on. For bacteria, the end product of fermenting sugar is a simple molecule called lactic acid, a weak acid with a rather sour taste. Yeast, one the other hand, produces a molecule called ethanol, the inebriating agent in alcohol. Humans figured out early on that both of these waste products could create tasty dishes while also helping food keep longer, as demonstrated in the three recipes below.

Pickling

Fermenting vegetable matter with bacteria (specifically strains of Lactobacillus) produces sour-flavored, long-lasting treats. Better known as “pickling,” this process is used in cuisines all around the world to crafts foods from kosher dills to kimchi. The process is thought to have originated thousands of years ago in Egyptian society.  

Beer

Fermenting grains or fruits with yeast is a tradition at least as old as pickling, and one that’s also known around the world. Luckily for folks who enjoy a beer or glass of wine with dinner, yeast converts sugars into alcohol instead of lactic acid. While the two substances have similar chemical formulas (lactic acid consists of  six hydrogen molecules, teamed with three carbon and three oxygen atoms, while alcohol binds six hydrogen atoms to a pair of carbon atoms and a single oxygen atom) they do very different things when they come in contact with our bodies and communicate with our brains—hence the difference between sour-tasting pickles and inebriating beer.

Sourdough Bread

But what happens when a concoction combines Lactobacillus and yeast? Sourdough bread is a good example of this forced symbiosis. Bakers have taken advantage of a wide array ofLactobacillus species and their close relatives to produce three kinds of sourdough bread. The lactic acid from the bacteria and carbon dioxide produced by the fermentation of yeast give this bread its distinctive tangy taste and fluffy texture. The fermentation process also converts the linoleic acid in bread flour into fatty acids that resist the growth of mold and help the loaf stay edible longer, a quality that made this food a favorite among gold surveyors in California. In addition, the presence of yeast means that sourdough freshly out of the oven will have some alcohol in it, although this content evaporates as time goes by.

Cheese

Lactobacillus bacteria consume milk in the guts of infants—and in fermented milk products like yogurt, sour cream and cheese. They produce lactic acid, which keeps fungi and bacteria from spoiling yogurt—and keeps disease-causing microbes from infecting people, too. That’s why they are a popular probiotic.

Learn more about microbes in The Secret World Inside You, now open at the Museum!

By far the largest population of bacteria in the human body is found in the colon. The majority are anaerobic, which means they don’t require oxygen and, of these, species of the genus Bacteroides are among the most common.

Outside the gut, strains of Bacteroides can cause abscesses in the abdomen, brain, liver, pelvis, and lungs, as well as bacteremia, an infection of the bloodstream. But in the colon, they serve important functions, breaking down carbohydrates, producing enzymes specifically designed to deal with different foods, and extracting energy from those foods. One species, B. fragilis, appears to stimulate immune cells called regulatory T-cells, which restrain more aggressive inflammatory T-cells, which can trigger colitis and other disorders.

Read more. 

The stomach is a highly acidic environment, and Helicobacter pylori is one of the few bacteria that can thrive there. H. pylori bacteria, shown here, are both a boon and a bother to humans. They help us regulate our immune system, prevent allergies and control our appetite. However, they can also cause ulcers and stomach cancer. 

Learn more in the new exhibition, The Secret World Inside You, opening November 7!