Do bacteria have any purpose?

Yes! Although they are the smallest of creatures, bacteria perform a vital role. They decompose dead things and the waste of living things. They support food chains as nutrients pass from bacteria to bacteria-eaters, and from them to secondary consumers. They fix nitrogen in the soil so that nitrogen compounds can be taken up by plants. Although a few species cause disease, without bacteria no other life could exist.

All this means that bacteria are intimately connected with the rest of life in a way that has nothing to do with their being the ancestors of all other organisms. They perform a great variety of functions, and their existence can be explained as the result of purpose rather than accident.

As we shall see shortly, their biological structure also shows evidence of purpose and design. While biologists have continually expected living things to be quite simple in structure and operation – reasonably enough, given that life arose by chance – research has found them time and again to be complex, more complex than anyone could have imagined, let alone expected. That is true not least of bacteria, the inner workings of which are still the focus of fundamental research.

How many are there?

A gram of soil contains about 1 million bacteria. We have between 5 million to 50 million per square inch on our teeth, most of them helping to digest food. A gram of our colon contains about 300 billion bacteria, and the total hosted by the human body is about 70 trillion: ten times the number of cells belonging to the body itself. No cause for worry, as most of these bacteria are beneficial. Altogether there are estimated to be around 30 million different species of microbe in the world, of which only 70 cause disease. We keep quite a few in our zoo. The huge number of different possible forms that bacteria can have shows how complex they are.

As well as living on and within animals, microbes live in plants, oceans, ocean sediments, hot springs, rivers, lakes, soils, deep under ground and in the air. The total number of microbes on the planet has been estimated at 5 million trillion trillion!

What do you mean by microbes?

Microbes is the ordinary word for ‘prokaryotes’, single-cell organisms without a nucleus. There are two categories of prokaryote, bacteria and ‘archaea’. Bacteria and archaea are as unlike each other as plants are from animals, if not more so, and since they are both believed to be ancient forms of life, there is no satisfactory way of ordering them into a single evolutionary tree. It seems as clear that bacteria did not evolve from archaea as it is that archaea did not evolve from bacteria.

All organisms that are not prokaryotes are eukaryotes, organisms that do have a nucleus in their cells. Thus the entire living world is divided into three fundamentally different groups: bacteria, archaea and eucarya. On the assumption that they must be related, Darwinists draw thin connecting lines between them, arranging them as a star rather than a tree. But a truer representation would have no such lines.

When were bacteria discovered?

Bacteria were first discovered in the late 1600s by an amateur Dutch scientist called Antoni van Leeuvenhoek (pronounced LAY-ven-hook), who learned to make magnifying lenses. His lenses were soon superior to anyone else’s, eventually being able to achieve magnifications of over 200 times. At the time scientists thought that the smallest kind of creature was the cheese mite. But Leeuvenhoek discovered that a single drop of canal water was teeming with tiny creatures. When he wrote to the Royal Society about them, members did not believe him, until the astronomer Christiaan Huygens tried using a similar lens. “I was wrong”, he said, “The little animals do exist.”

  

Pasteur

After that no one did any serious work on bacteria until the French chemist and biologist Louis Pasteur (1822-1895). He was asked by people in the brewing industry to research into why beer sometimes went sour. He found that this was caused by the action of bacteria: an important discovery not only for the brewers, but for wine-makers and the food industry generally. He invented the process of heating liquids – called pasteurisation – just enough to kill harmful bacteria.

Most scientists of his day thought that bacteria could arise all by themselves, from non-living matter. This was the theory of spontaneous generation. Pasteur proved that bacteria could only come from other bacteria, though they were often carried in the wind on dust particles.

What are bacteria like?

Any description of bacteria must grossly simplify what they are like, but here are a few points to give an idea:

• Bacteria consist of a single fluid-filled cell enclosed by an envelope. The envelope consists of a membrane and a cell wall. The fluid within the membrane, known as the cytoplasm, contains nucleic acids (DNA and RNA), enzymes, amino acids, carbohydrates and lipids.
• Also within the cytoplasm are ribosomes, factories which translate the DNA’s genetic code into amino acids to make proteins. Proteins are the molecules that perform the various functions in a cell: transportation, storage, catalysing chemical reactions, providing structure and so on. Some bacteria use more than 1,000 different types of protein.
• DNA is 4.5 x 10¹³ more efficient than a man-made silicon chip. It is like a computer program that controls the whole activity and multiplication of a bacterium. Bacteria can reproduce themselves every 20 minutes.
• The membrane has pores that, with the help of numerous proteins, allow food to pass one way and waste the other. The cell wall maintains the shape and structure of the bacterium.
• Bacteria generate energy by means of a molecule called ATP, as do all other forms of life. This molecule alone has a level of organization equivalent to a research microscope or a standard television.
• Some bacteria move along by means of a rotating tail, or flagellum. This too is a highly complex piece of engineering.
• Some bacteria have tubes called pili on the cell wall. These are instruments of adhesion that enable the bacterium to colonise surfaces (including host cells) and avoid being flushed away. Pili are continually being lost and replaced, and some bacteria can change the tips of the pili according to which type is most effective for adhering to a host cell.

  

How do you make bacteria?

As in Pasteur’s day, many scientists think that the first bacteria came into existence spontaneously, out of a chemical soup. This idea has been renamed abiogenesis rather than spontaneous generation, but it is essentially the same. The hope of making ‘life’ in a test-tube is not unlike the medieval alchemist’s dream of turning base metals into gold. Even today it is common for scientists to speak as if all that was required for bacteria to form was the ‘right conditions’.

In 1953 the scientists Stanley Miller and Howard Urey attempted to give substance to the idea by sending electricity through a mixture of methane, ammonia, hydrogen and water. They found that they could make some amino acids.

However, amino acids are not life – they have even been found on meteorites – and no scientist has ever succeeded in manufacturing an artificial biological cell from raw materials, whether by simulating chance processes or by deliberately playing the role of creator. Cells are information systems. They are much too complex for self-assembly to be a credible explanation.

ATP – one of the most efficient machines known

Bacteria generate energy using a complex macromolecule called ATP (adenosine triphosphate). ATP is like a biochemical “bearing”, 200,000 times smaller than a pinhead. Set in the walls of the membrane, the molecule spins at 6,000 rpm (100 times per second) and makes energy by a reaction that releases hydrogen ions and converts the ATP to ADP (adenosine diphosphate). The ADP is then recycled in the membrane and recharged to come out again as ATP, as illustrated in the diagram below. The machine was discovered in 1997 by two scientists who were awarded the Nobel Prize for their work.

The bacterial flagellum

In the journal Current Biology (7 November 2006) David DeRosier describes this remarkable appendage as follows:

The flagellum, with its complexity of structure and multiplicity of function, is a machine that boggles the mind. While musing on possible phrases that might catch the reader’s attention, I was reminded of the memorable 1926 slogan for the Hoover vacuum cleaner: “It beats as it sweeps as it cleans.” The flagellum self-assembles as it propels as it responds; that is, the flagellum not only pushes the cell along, it also responds to intracellular signals and it assembles itself. It seems as amazing as the old Hoover did in its heyday. But, I thought, the bacterial flagellum does not really ‘beat’; the eukaryotic flagellum, an entirely different machine, does that. Instead, the prokaryotic flagellum spins, driven by a rotary motor at speeds of over 100,000 rpm in at least one species. The torque generated by the motor is converted to thrust by the corkscrew-shaped filament or propeller.

The flagellum is not merely like a machine, it is a machine, consisting of a propellor, a universal joint, a drive shaft and a rotary motor. The way that unintelligent Nature has gone before us with engineering concepts identical to those man has devised can be quite disconcerting!

Conclusion

Although Nature is unintelligent, that need not prevent us from recognising the intelligence that lies behind its works. The idea that complexity of the kind we see in bacteria could arise by itself is not something we can infer from the nature of the bacteria themselves. Rather, we know from experience that complex machines require a designer and engineer.

The existence of even these simplest of creatures, therefore, is sufficient evidence that a Creator exists.

See also:
More than 20,000 different types of microbe in a single litre of water