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I Contain Multitudes

From Walt Whitman's “I am large, I contain multitudes.”

Fun Facts

  1. the average person contains ten microbial cells for every human one... (is wrong. See: https://www.cell.com/cell/pdf/S0092-8674(16)00053-2.pdf. Ratio is ~ 1:1)

  2. (Numbers wrong in the book but substantive point holds with new info.)

    "In total, there are ∼1,400 known species of human pathogens (including viruses, bacteria, fungi, protozoa and helminths), and although this may seem like a large number, human pathogens account for much less than 1% of the total number of microbial species on the planet."

    https://www.nature.com/articles/nrmicro2644

  3. bacterial genes/human genes in the human biome ~ 300x

  4. Westerners carry a much lower diversity of gut microbes than rural villagers from Burkina Faso, Malawi, and Venezuela. Plausibly rooted in fiber as bacteria are key to digesting fiber throughout the animal kingdom. "Now, the implication. The very first mammals were carnivores – small, scurrying, scourges of insects. Shifting from meat to plants was an evolutionary breakthrough for our group. ... So, mammalian success was founded on vegetarianism, and that vegetarianism was founded on microbes."

  5. Well known but imp.: "People are 7 to 10 times more likely to get C. diff while on antibiotics and during the month after."

  6. Take Helicobacter pylori, ...Blaser was partly responsible for ruining ...confirmed that it increases the risk of stomach cancer, too. Only later did he realise the microbe’s beneficial side: it reduces the risk of reflux (a condition where stomach acid gurgles back into the throat), oesophageal cancer, and perhaps asthma. ... Once ubiquitous, H. pylori is now found in just 6 per cent of children in Western countries..."In a large study of almost 10,000 people, Blaser showed that the presence or absence of H. pylori had absolutely no effect on a person’s risk of dying at any given age."

  7. David Mills’s team recently noticed that B. infantis is present in 60 to 90 per cent of infants from developing countries like Bangladesh or Gambia, but just 30 to 40 per cent of infants in developed nations like Ireland, Sweden, Italy, and the USA

  8. Then, Jones noticed a big clue. The worm’s trophosome, a mysterious organ that made up half its body weight, was packed with crystals of pure sulphur. ...Cavanaugh’s epiphany was both right and revolutionary.11 Under the microscope, she found that Riftia’s trophosome was full of bacteria, about a billion of them for every gram of tissue. ...really thrive, you need a different source of energy. For Riftia’s bacteria, that’s sulphur, or rather the sulphides that spew out of the vents. The bacteria oxidise these chemicals and use the liberated energy to fix carbon. This is chemosynthesis: making your own food using chemical energy instead of light or solar energy. And rather than producing oxygen as a waste product, as photosynthetic plants do, these chemosynthesising bacteria churn out pure sulphur.

  9. By sundering plant carbohydrates with their broad toolkits, B-theta and other microbes release substances that directly nourish our own cells. Collectively, they provide 10 per cent of our energy intake, and a whopping 70 per cent of a cow’s or sheep’s.

  10. "They noticed that harmless strains of Pneumococcus could suddenly start causing disease after mingling with the dead and pulped remains of infectious strains. Something in the extracts had changed them. In 1943, a “quiet revolutionary” named Oswald Avery showed that this transformative material was DNA, which the non-infectious strains had absorbed and integrated into their own genomes."

  11. Small data magic: "Keller’s team recruited patients with recurring C-diff infections and randomly assigned them to receive either vancomycin or an FMT. They originally planned to recruit 120 participants, but they only made it to 42. By that point, vancomycin had cured just 27 per cent of the people who received it, while FMT had cured 94 per cent."

  12. "He found that thoroughly scrubbed toilets are first colonised by faecal microbes, which are launched into the air by roiling, flushed water. Those species are eventually outcompeted by a diverse range of skin microbes, but once the toilet gets scrubbed again, the communities go back to square one. So, here’s the irony: toilets that are cleaned too often are more likely to be covered in faecal bacteria."

Bacteria in Action

  • The Colorado potato beetle, a major pest, uses bacteria in its saliva to suppress the defences of the plants that it eats.

  • Termites depend on the digestive services (of bacteria)

  • Lichens – those splotches of colour growing on walls, stones, barks, and logs – are composite organisms, consisting of microscopic algae that live alongside a fungus host, providing nutrients in exchange for minerals and water.

  • If the algae rise, the corals fall, and vice versa. In most reefs, fleshy algae are kept in check by grazers like surgeonfish and parrotfish, which nibble them down to well-trimmed lawns. But humans kill the grazers with spears, hooks, and nets. We also kill top predators like sharks, leading to population explosions of medium-sized predators, which then take out the grazers. Either way, we give the algae an advantage. The well-trimmed lawns become overgrown fields, and the neighbouring corals start to die. Jennifer Smith, who was also on the Line Islands expedition, demonstrated this through a simple experiment. She placed nubbins of coral and scraps of algae in adjacent aquaria, connected by the same water but separated by one of those extremely fine filters. Microbes could not pass through but chemicals in the water could. Within two days, all the corals were dead. Something in the water, released by the algae, was killing them. A toxin? Possibly, but when Smith treated the corals with antibiotics, they survived. Not a toxin, then. Not spreading microbes, either – the filters would have blocked their path. No, the algae were making something that killed the corals via their own microbes.

  • Oliver showed that when Hamiltonella carries a particular phage strain, it renders aphids almost totally wasp-proof. If the virus disappeared, the same bacterium became useless, and almost all of its aphid hosts succumbed to their parasites. ... Moran found one possible answer: sex. Males carry Hamiltonella and other defensive symbionts in their semen. When they have sex, they can pass these microbes to the females, who can then inoculate their offspring. So females, by mating with the right partners, can suddenly become immune to wasp attacks, which makes Hamiltonella that rarest of things: a desirable venereal infection.

  • In Ghana, doxycycline sterilised the female worms, and in Tanzania, it wiped out the larvae.3 And at both sites, it killed the adult nematodes in around three-quarters of the volunteers, without triggering any catastrophic immune responses. That was huge. “For the first time, we were able to cure people of filariasis,”

How New

  • "In 2005, Relman found the same pattern in the gut. Using three volunteers, he collected samples from various points along their intestines, and identified almost 400 species of bacteria and one archaeon – 80 per cent of which were new to science."

More or Less Fake News

  • When babies emerge from the womb they are colonised by mum’s vaginal microbes – an endowment that creates chains of transmission which cascade through generations. This, too, is changing. Around a quarter of babies in the UK and ...This might explain why C-section babies are more likely to develop allergies, asthma, coeliac disease, and obesity later in life.