Bacteria, pathogenic bacteria, a kingdom for bacteria

Dr Irengbam Mohendra Singh *

In Norse mythology [similar to Meitei mythology of creation] a pantheon of gods who live in the realm of Asgard, created humans and the world. Asgard is located in the sky and is connected to Midgar, the world of humans. This Etema, professor of Cell and Molecular Biology at Upsale University, Netherlands, while researching for our ancestor microbes, has named Asgard for a large clan of microbes.

He has also named its members after Norse gods, such as Odin, Thor, Loki, and Heimdall, which are found all over the world. Most of them have never been seen under a microscope. Only the DNA analysis shows that they exist. He says they are important to us, because they may well be the groups from which we evolved.

In fact, the newfangled scientific research has discovered that humans have evolved from complex bacteria (Eukaryotic cells) 2 billion years ago. So have other animals, plants and fungi. And this common ancestor had itself evolved from simple bacteria (Pakaryotic cells) that had lived in the first 2 billion years of life on Earth.

Another exciting discovery in the 1970s, is the discovery of mitochondrial cells living inside bacterial cells endosymbiotically. As they have the same DNA similar to the free living bacteria, it's believed that the bacteria must have swallowed them in the past, and instead of digesting, the mitochondrial cells were allowed to live to provide and conserve energy ATP (Adenosine triphosphate) for the host. Humans and all complex cells of eukaryotes have mitochondria (cf. author's book The origin of Meiteis. 2009:72).

It's estimated that 7 million species of animals live on Earth today. The origin of animals (humans) is one of the most serious scientific research, as some of the intermediate species that might show how transition took place have become extinct. It's estimated that over 5 billion species (99%) that lived on Earth have become extinct.

It's nice to read the Bible and its mythology of creation, and the book, The pleasing of the Gods: Meitei Lai Haraoba by Saroj N Arambam Parratt and John Parratt (well-researched and the only one of its kind in English). 'Lai Haraoba' was first literally translated by Lt Col John Shakespear as 'pleasing of the god' (Lai is singular). He was Political Agent in Manipur from 1905 to 1914. His surname differs from William Shakespeare by the absence of 'e' at the end.

Lai Haraoba is Meitei culture of reenacting the creative stories of ancient Meiteis. This is Meitei culture ie beliefs, norms, ideas etc, by the measurement of which we can measure Meitei civilisation. It's of no intrinsic value in our search for Meitei origin. Similarities in cultures do not prove common descent or evolution, as they could be explained equally by a common design plan. Only the similarities in genetic makeup could prove it.

Charles Darwin's book, On the Origin of Species (1959), removed the artificial distinction between humans and other forms of life for good. The modern scientific view is that life ie the first simple unicellular bacteria began in the wet rocky hollows 4 billion years ago.

This hypothesis is alluded to the Greek mythology of creation, in which a demigod Prometheus (8th century) created humans from clay (cf. promethean clay) after stealing fire from the gods and giving life to the clay model, for which he was punished by Zeus, king of the Olympian gods. In the West, Prometheus became a figure who represented human effort, particularly the quest of scientific knowledge.

Based on this Greek mythology, Mary Shelly wrote her novel Frankenstein; or, The Modern Prometheus (1823), in which she tried to stage whether the vital force that separates the living from the dead could be electricity, after assembling a human corpse with dead inanimate pieces.

The creator Victor Frankenstein (in the novel) did revive the corpse with electricity, simply known as monster, and later, as Frankenstein. He behaved like a human being with sentiments and feelings, but he was not accepted in the society. Failing to integrate, he later took revenge on his creator.

In trying to find the vital force that separates the living from the non-living, scientists have at least, found the first unicellular 'bacteria' that lived 4 billion years ago, and from which had evolved all living things including humans we find today. Bacteria and recently discovered archaea are microscopic forms of life.

When I was little, like everybody else, I knew what germs were, as invisible tiny creepy crawly nasty things that were everywhere and caused diseases. In school, I talked about bacteria as fancy word for germs. Nobody knew what they were. As I went to college, still no one had a clue whether bacteria were animals or plants.

Now we, in the business, know bacteria (bacterium – singular) that are neither plants nor animals, and that germs consist of bacteria, viruses, fungi, and protozoa. Bacteria have a large kingdom. In their origin and evolution, the present bacteria are ancient cousins of humans. They appeared on Earth about 4 billion years ago.

Humans and other living organisms are descended from bacterialike ancestors, but about 2 billion years ago human ancestors branched off. This branch, called eukaryotes, also gave rise to other animals, plants, fungi and protozoa. Modern form humans (Homo sapiens) evolved only 200,000 years ago.

Bacteria are one-celled creatures that get their nourishment from others to live. They can't make their own food. So they invade plants and animals, and some of them make plants and animals including us sick. The ancestors of bacteria on Earth, before they evolved into what they are now, were unicellular microorganisms ie living things. Bacterial fossil findings are recorded to be 4 billion years old. These fossils show that bacteria lived on Earth without oxygen for over 3.4 billion years ago, when Earth was still very hot and violent with frequent earthquakes.

Not so long ago, at the end of the 20th century, biologists found another unicellular organisms, now called Archaea, which under the microscope, look just like bacteria. They live in the most hostile environments, like the hot springs of Yellowstone National Park, USA. Some live near rift vents in the deep sea, at temperatures well over 100 degrees Centigrade. Some live under Antarctic ice on a diet of methane and ammonia. They are a major source of methane and thus play a role in global ecosystems with other organisms.

In late 1970, Dr. Carl Woese and his colleagues at the University of Illinois, shocked the scientific community declaring that, using DNA sequences, he found bacteria and archaea were two distinctly different. In the 1950s, when I was studying biology in the college, all living things were classified in two kingdoms, as either a plant or an animal.

By 1970s, biologists have agreed on a model of five kingdoms:
(1) Prokaryote eg bacteria, blue-green algae;
(2) Prototicsta eg amoeba, paramecium;
(3) Fungi eg moulds, mushrooms, yeast;
(4) Plantae – all green plants; and
(5) Animalia – all multicellular animals.

It's estimated that there are about 1031 (ie 10 multiplied by 10 for 31 times) bacteria on Earth. Bacteria are organisms known as prokaryotes that do not have a cell nucleus. Bacteria were first discovered in 1672 by a Dutch named Van Leeuwenhoek, when he tried to discover why pepper was hot. He was not a trained scientist.

His efforts using dried pepper failed, and so he put a handful of peppercorns in water and let them soften for three weeks. He drew some of the water into a glass capillary tube and looked at it under his single tiny lens. To his surprise, it was full of an incredible number of "animacules". He didn't realise at that time that they were bacteria. A year later, he discovered spermatozoa (motile male sex cells of an animal).

A special photosynthetic bacteria we should be grateful to are cyanobacteria or blue-green algae (prokaryote) that live in water. They helped to turn our planet green and paved the way for us and other animals to flourish, by saturating the atmosphere with oxygen that we breathe. There is uncertainty regarding how and when cyanobacteria came to live on Earth. Scientists puts it down to roughly 2.7 billion years ago in the 'Great Oxidation Event'. Plants did not exist during that time.

It's thought that some bacteria adapted this photosynthetic machinery to produce Adenosine Triphosphate (ATP) for storing energy – life's battery. They evolved to make their own food by taking energy from sunlight, and using it to make sugars out of water and carbon dioxide. But unlike present plants, they lack chloroplasts but have light-harvesting pigments. It's called oxygenic photosynthesis.