Gut Colonies Make Us Superorganisms
September 17, 2018 at 3:18 p.m.
By Max [email protected]
This collection or community of organisms is called the microbiota. The collection of the genomes of the microbiota is defined as the microbiome and consists of over 3 million genes that produce thousands of metabolites. They replace many of the functions of each of us and influence our fitness, phenotype (observable characteristics or traits) and health. The microbiota is part of the human ecosystem.
According to one author, the armies of bacteria that sneak into our bodies the moment we are born are the “primal illegal immigrants.” Most are industrious and friendly, minding their own business in tight-knit, long-lived communities, doing the grunt biochemical work we all rely on to stay alive. The ecosystem forms at birth, but the human-microbe alliance begins months before.
Midway through pregnancy, a hormonal shift directs the cells lining the vagina to begin stockpiling sugary glycogen, the favorite food of sausage-shaped bacteria called lactobacilli. By fermenting the sugar into lactic acid, these bacteria lower the pH of the vagina to levels that discourage the growth of potentially dangerous invaders.
The infant mouth’s first inoculation of bacteria includes a generous sampling of the lactobacilli present in the mother’s birth canal. With the first gulp of breast milk, these lactobacilli are joined by millions of bifidobacteria, a related group of acid-producing microbes. The source of these bacteria are the mother’s nipples, where the bacteria appear during the eighth month of pregnancy.
Bifidobacteria secrete acids and antibiotic chemicals that repel potentially dangerous organisms including Staphylococcus aureus. Bifidobacteria and lactobacilli are soon joined with acid-tolerant Streptococcus salivarius that appear on a baby’s tongue during the first day of life. Bifidobacteria are anaerobic (surviving without oxygen) rods that break down dietary carbohydrates and synthesize and excrete water-soluble vitamins. Their name is derived from the observation that they often exist in a Y-shaped form.
These organisms predominate in the colons of breast-fed babies and account for up to 95 percent of all culturable bacteria and protect against infection. Strangely, they do not occur in such high numbers in adults. Several other streptococci along with one or more kinds of Neisseria bacteria settle in during the first week. The vast majority emanate from the mother’s mouth, which is always within reach of a nursing baby’s fingers.
As the baby begins nursing or drinking formula, the bacterial population inside the mouth increases. These bacteria consume enough oxygen, creating a zone where anaerobic bacteria can thrive. By the time the baby is 2 months old, a microscopic close-up of the gums will reveal clusters and chains of bacteria and fungi.
Another wave of bacteria arrives when the first teeth appear. The first is Streptococcus sanguis, followed by Streptococcus mutans. By middle childhood, the diversity inside the mouth surpasses a hundred species, and their total number is greater than 10 billion. Bacteria also settle in the nasal cavities, which are connected to the mouth via the upper respiratory tract. The bacteria eventually lodge in the intestinal tract. In the small intestine, incoming microbes engage the infant’s dormant immune system.
When the child grows up to become an adult, his or her intestine is home to an almost inconceivable number of micro-organisms. The size of the population — up to 100 trillion (a trillion seconds in time would be 32,000 years) — far exceeds all other microbial communities associated with body’s surfaces and is more than 10 times greater than the total number of our somatic and germ cells. (There is a significant variation in the total number of bacteria and the composition of the bacterial flora in different body regions.)
With aging, environmental factors related to diet, drugs and pesticides continue to affect the composition of our microbiota. Since humans depend on their microbiota for various essential services, a person should really be considered a superorganism, consisting of his or her own cells and those of all the bacteria. A superorganism could also be described as colonies of individuals tightly knit by cooperation, complex communication and division of labor.
We are indeed fortunate. Humans are not inherently endowed with a healthy immune or digestive system. Fortunately, our intestinal tract, which includes our inhabitants (microbiome), provides us with genetic and metabolic attributes we have not been required to evolve on our own, including the ability to harvest otherwise inaccessible nutrients and to modify host immune reactivity. There is still a lot to learn; however, scientists continue the effort to understand how microbes colonize the gut and to identify the genes that help microbes pass through the stomach's harsh environment and survive in the lower gastrointestinal tract.
Max Sherman is a medical writer and pharmacist retired from the medical device industry. He has taught college courses on regulatory and compliance issues at Ivy Tech, Grace College and Butler University. Sherman has an unquenchable thirst for knowledge on all levels. Eclectic Science, the title of his column, will touch on famed doctors and scientists, human senses, aging, various diseases, and little-known facts about many species, including their contributions to scientific research. He can be reached by email at [email protected].
This collection or community of organisms is called the microbiota. The collection of the genomes of the microbiota is defined as the microbiome and consists of over 3 million genes that produce thousands of metabolites. They replace many of the functions of each of us and influence our fitness, phenotype (observable characteristics or traits) and health. The microbiota is part of the human ecosystem.
According to one author, the armies of bacteria that sneak into our bodies the moment we are born are the “primal illegal immigrants.” Most are industrious and friendly, minding their own business in tight-knit, long-lived communities, doing the grunt biochemical work we all rely on to stay alive. The ecosystem forms at birth, but the human-microbe alliance begins months before.
Midway through pregnancy, a hormonal shift directs the cells lining the vagina to begin stockpiling sugary glycogen, the favorite food of sausage-shaped bacteria called lactobacilli. By fermenting the sugar into lactic acid, these bacteria lower the pH of the vagina to levels that discourage the growth of potentially dangerous invaders.
The infant mouth’s first inoculation of bacteria includes a generous sampling of the lactobacilli present in the mother’s birth canal. With the first gulp of breast milk, these lactobacilli are joined by millions of bifidobacteria, a related group of acid-producing microbes. The source of these bacteria are the mother’s nipples, where the bacteria appear during the eighth month of pregnancy.
Bifidobacteria secrete acids and antibiotic chemicals that repel potentially dangerous organisms including Staphylococcus aureus. Bifidobacteria and lactobacilli are soon joined with acid-tolerant Streptococcus salivarius that appear on a baby’s tongue during the first day of life. Bifidobacteria are anaerobic (surviving without oxygen) rods that break down dietary carbohydrates and synthesize and excrete water-soluble vitamins. Their name is derived from the observation that they often exist in a Y-shaped form.
These organisms predominate in the colons of breast-fed babies and account for up to 95 percent of all culturable bacteria and protect against infection. Strangely, they do not occur in such high numbers in adults. Several other streptococci along with one or more kinds of Neisseria bacteria settle in during the first week. The vast majority emanate from the mother’s mouth, which is always within reach of a nursing baby’s fingers.
As the baby begins nursing or drinking formula, the bacterial population inside the mouth increases. These bacteria consume enough oxygen, creating a zone where anaerobic bacteria can thrive. By the time the baby is 2 months old, a microscopic close-up of the gums will reveal clusters and chains of bacteria and fungi.
Another wave of bacteria arrives when the first teeth appear. The first is Streptococcus sanguis, followed by Streptococcus mutans. By middle childhood, the diversity inside the mouth surpasses a hundred species, and their total number is greater than 10 billion. Bacteria also settle in the nasal cavities, which are connected to the mouth via the upper respiratory tract. The bacteria eventually lodge in the intestinal tract. In the small intestine, incoming microbes engage the infant’s dormant immune system.
When the child grows up to become an adult, his or her intestine is home to an almost inconceivable number of micro-organisms. The size of the population — up to 100 trillion (a trillion seconds in time would be 32,000 years) — far exceeds all other microbial communities associated with body’s surfaces and is more than 10 times greater than the total number of our somatic and germ cells. (There is a significant variation in the total number of bacteria and the composition of the bacterial flora in different body regions.)
With aging, environmental factors related to diet, drugs and pesticides continue to affect the composition of our microbiota. Since humans depend on their microbiota for various essential services, a person should really be considered a superorganism, consisting of his or her own cells and those of all the bacteria. A superorganism could also be described as colonies of individuals tightly knit by cooperation, complex communication and division of labor.
We are indeed fortunate. Humans are not inherently endowed with a healthy immune or digestive system. Fortunately, our intestinal tract, which includes our inhabitants (microbiome), provides us with genetic and metabolic attributes we have not been required to evolve on our own, including the ability to harvest otherwise inaccessible nutrients and to modify host immune reactivity. There is still a lot to learn; however, scientists continue the effort to understand how microbes colonize the gut and to identify the genes that help microbes pass through the stomach's harsh environment and survive in the lower gastrointestinal tract.
Max Sherman is a medical writer and pharmacist retired from the medical device industry. He has taught college courses on regulatory and compliance issues at Ivy Tech, Grace College and Butler University. Sherman has an unquenchable thirst for knowledge on all levels. Eclectic Science, the title of his column, will touch on famed doctors and scientists, human senses, aging, various diseases, and little-known facts about many species, including their contributions to scientific research. He can be reached by email at [email protected].
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