• Joan Rothchild Hardin

Astonishing Microbes!

Bacteria and other microbes possess some quite amazing qualities. Here are a few mind boggling tricks they have up their metaphorical sleeves. Microbes in a Petri Dish


A world without bacteria and other microbes wouldn’t support life as we know it. We and other animals wouldn’t be able to digest food without the microscopic critters who live in our gut microbiomes. Waste water treatment systems would fail. Nothing would be able to decompose so waste would  pile up. The nutrient recycling underlying life as we know it would cease. Oceans would become virtually nonproductive. Asphyxiation of aerobic life would occur.

The authors of an article on the topic state: “We predict complete societal collapse only within a year or so, linked to catastrophic failure of the food supply chain. Annihilation of most humans and nonmicroscopic life on the planet would follow a prolonged period of starvation, disease, unrest, civil war, anarchy, and global biogeochemical asphyxiation.” (Gilbert & Neufeld, 2014)

This is not to say that ALL life on earth would completely cease without the work of microorganisms, only that the TYPE of life that could survive in the absence of all microbes would be very different from life as we know it, drastically reduced in both quantity and quality.


Aside from the serious fix we’d be in without bacteria and other microbes, here are some additional amazing things bacteria can do. BACTERIA COMMUNICATE WITH EACH OTHER: QUORUM SENSING

“Although bacteria are primitive single-celled organisms, their ability to use chemical signals to communicate with each allows them to synchronize their behavior and act together much like large, multi-cellular organisms.” (Hardin, 1/28/2016)

Scientists call this cell to cell signaling process among bacteria Quorum Sensing. Each bacterium measures the concentration of its fellows by sending out a chemical signal and  ‘listening’ for the chemical signals from other like bacteria.

Here’s a description of what quorum sensing does for bacteria living symbiotically on the bioluminescent lantern fish: Bioluminescent Lantern Fish


Lantern fish (family: Myctophidae) are a family of deep-sea fish comprising about 65% of the fish biomass in the deep seas. Photophores in species-specific patterns line the lateral and ventral sides of all but one species of myctophids. It’s thought that these bioluminescent patterns are used to lure prey and to signal potential mates for their hosts. Some lantern fish also have very bright photophores near the base of their tails, possibly for the purpose of disorienting predators with a blinding flash so the lantern fish can swim to safety.

As if that’s not amazing enough, the fish’s photophores are powered by symbiotic light-emitting bacteria.

Ken Nealson, Wrigley Chair in Environmental Studies and Professor of Earth Sciences and Biological Sciences at the University of Southern California, studies bioluminescent bacteria that live symbiotically with the lantern-eye fish found in the Red Sea. These bacteria develop into colonies inside special cavities beneath the fish’s eyes, “but only after generating a dense cluster of ten million cells will they glow…. Nealson was curious: were the microbes somehow taking a census of themselves? It turned out they were, using chemical signals. When the bacteria were let loose in seawater, the census failed, and they refused to grow.” (Khatchadourian, 6/20/2016)



Bacteria not only use quorum sensing to measure the concentration of members of their own kind to assess whether there are enough for engaging in group behavior but  they can also poll members of OTHER bacterial species.

“While species-specific quorum sensing apparently allows recognition of self in a mixed population, it seems likely that in such situations, bacteria also need a mechanism or mechanisms to detect the presence of other species. Additionally, it is conceivable that it is useful for bacteria to have the ability to calculate the ratio of self to other in mixed populations, and in turn, to specifically modulate behavior based on fluctuations in this ratio.” (Federle & Bassler, 2003)

Pretty clever for a primitive organism consisting of only a single cell!

See How Bacteria Talk To Each Other for more information and some fascinating videos on how bacteria use quorum sensing to communicate.

And – by the way – there’s also evidence that plants communicate with each other via collective decision making too! So do many social insects – including ants and honey bees. (Wikipedia, 6/23/2016)


THE FORMATION OF PROTO-EARTH Rendering showing the formation of proto-earth and the rest of the solar system as it coalesced out of the remains of dust clouds produced by earlier generations of supernovas created during the Big Bang.  Particles clumped together to form planetessimals, which were made of various combinations of:

  • Ices (frozen gasses, including water)

  • Organics (carbon-rich compounds)

  • Silicates (“rock”)

  • Metals


Primordial earth came into being about 4.57 billion years ago, formed from a giant rotating cloud of gasses and dust. The dust consisted of debris still around from the huge explosion referred to as the Big Bang, which astrophysicists estimate took place about 15 billion years ago. “The dust particles collided with each other, merging into larger particles. These larger particles collided in turn, joining into pebble-sized rocks that collided to form larger rocks, and so on. The process continued, eventually building up the earth and other planets.”  (MarineBio, 2015)

In its initial form, earth was a geologically violent place, constantly bombarded by meteorites. Proto-earth was a vision of hell: Heat produced as proto-earth developed into planet earth likely caused the whole mass to be molten. Raging hot sea water covered its surface. Lava from early earth’s core spewed out on a regular basis. There was no oxygen yet, only a scalding atmosphere of carbon dioxide, nitrogen, water vapor, and others gasses. (Appenzeller, 2006) & (BBC, 2016) Molten Proto-Earth – A Scalding Atmosphere Containing No Oxygen


As this phase ended, the planet cooled and its surface solidified into a crust. PROKARYOTES: THE FIRST LIFE FORMS ON EARTH The first life forms to appear on this developing planet about 3.8 to 3.5 billion years ago were single-celled prokaryotes. Prokaryotes are anaerobic (not requiring oxygen) and the smallest and simplest microorganisms on the planet. Prokaryotes don’t have a nucleus, mitochondria or any other membrane-bound organelles. “In other words neither their DNA, nor any of their other sites of metabolic activity, are collected together in a discrete membrane enclosed area. Instead everything is openly accessible within the cell, some free floating, some bound to the walls of the cell membrane”. Prokaryotes constitute the most plentiful and diverse group of organisms on earth. They include bacteria and cyanobacteria. (Ramel, undated)


It makes sense that the prokaryotes would be earth’s first life form. They’re tough little critters.  Prokaryotes “hold all the records for living in the coldest, hottest, most acidic and most highly pressurized environments. They live in incredible places such as miles beneath the earth in bare rock, under glaciers, floating around in clouds and miles down on the sea floor, or at temperatures greater than 100 C. They are also the worlds experts at surviving bad times. In 2000AD scientists at West Chester University Pennsylvania succeeded in waking up the resting spores of a bacterium (Bacillus permians) that was last active 250 million years ago.” (Ramel, undated)


Now we come to the fascinating part about how these early cyanobacteria created earth’s oxygen-rich atmosphere, enabling the development of more complex, macro life forms. Cyanobacteria – Prokaryotic Bacteria That Obtain Energy Through Photosynthesis


Cyanobacteria is a phylum of prokaryotic bacteria that obtain their energy through photosynthesis. The name derives from the blue green color of the bacteria.


It was the oxygen produced by cyanobacteria, those early prokaryotics that engaged in photosynthesis, that started earth on its path toward an oxygen-rich atmosphere.

Complex life forms need oxygen. “You cannot evolve animals like us without having a significant amount of oxygen”, says Geochemist Dick Holland of Harvard University. “Without the Great Oxidation Event [a dramatic rise of oxygen in Earth’s atmosphere some 2.3 billion years ago], we would not be here. No dinosaurs, no fish, no snakes – just a lot of microorganisms.

“Cyanobacteria or blue-green algae became the first microbes to produce oxygen by photosynthesis, perhaps as long ago as 3.5 billion years ago and certainly by 2.7 billion years ago. But, mysteriously, there was a long lag time – hundreds of millions of years – before Earth’s atmosphere first gained significant amounts oxygen, some 2.4 billion to 2.3 billion years ago.” (, 2016) EARTH REALLY BELONGS TO MICROORGANISMS, NOT HUMANS

From a NOVA interview with Andrew Knoll, Fisher Professor of Natural History and a Professor of Earth and Planetary Sciences at Harvard University, author of Life on a Young Planet: The First Three Billion Years of Life:

“NOVA: When people think of life here on Earth, they think of animals and plants, but as you say in your book, that’s really not the history of life on our planet, is it?

“Andy Knoll: It’s fair to say when you go out and walk in the woods or on a beach, the most conspicuous forms of life you will see are plants and animals, and certainly there’s a huge diversity of those types of organisms, perhaps 10 million animal species and several hundred thousand plant species. But these are evolutionary latecomers. The history of animals that we’ve recorded from fossils is really only the last 15 percent or so of the recorded history of life on this planet. The deeper history of life and the greater diversity of life on this planet is microorganisms—bacteria, protozoans, algae. One way to put it is that animals might be evolution’s icing, but bacteria are really the cake.

“NOVA: So we live in their world rather than the other way around?

“Andy Knoll: We definitely live in a bacterial world, and not just in the trivial sense that there’s lots of bacteria. If you look at the ecological circuitry of this planet, the ways in which materials like carbon or sulfur or phosphorous or nitrogen get cycled in ways that makes them available for our biology, the organisms that do the heavy lifting are bacteria. For every cycle of a biologically important element, bacteria are necessary; organisms like ourselves are optional.” (PBS, 7/1/2004) HOW SINGLE CELL ORGANISMS BANDED TOGETHER TO PRODUCE LARGER LIFE FORMS: BIOFILMS

So how did microscopic bacteria manage to band together to produce macro life forms like plants, worms, insects, birds, fish, dinosaurs, and us? Remember bacteria’s ability to communicate with each other via quorum sensing? Not only are bacteria able to perform quorum sensing, they also are able to adhere together into biofilms. In both instances, microbes are engaging in social behavior. Diagram of Van Leeuwenhoek’s 17th Century Simple Microscope