History of Bacteria evolution

Finding: The evolutionary history of bacteria has been worked out.

Unlike other organisms that tend to pass their genes on to the next generation of their own species, bacteria often exchange genetic material with totally unrelated species a process called lateral gene transfer.

Researchers did not believe that they could work out the evolutionary history of bacteria. But now, thanks to the availability of sequenced genomes for groups of related bacteria, and a new analytical approach, researchers at have been able to demonstrate that constructing a bacterial family tree is indeed possible.

Here is how they do it
Scientists propose an approach that begins by scouring genomes for a set of genes that serve as reliable indicators of bacterial evolution. This method has important implications for biologists studying the evolutionary history of organisms by establishing a foundation for charting the evolutionary events, such as lateral gene transfer, that shape the structure and substance of genomes.

In this study, the researchers chose the ancient bacterial group called gamma Proteobacteria, an ecologically diverse group (including Escherichia coli and Salmonella species) with the most documented cases of lateral gene transfer and the highest number of species with sequenced genomes.

Why use bacteria at all?
Bacteria promise to reveal a wealth of information about genomic evolution, because so many clusters of related bacterial genomes have been sequenced--allowing for broad comparative analysis among species--and because their genomes are small and compact.

The results support the ability of their method to reconstruct the important evolutionary events affecting genomes. Their approach promises to elucidate not only the evolution of bacterial genomes but also the diversification of bacterial species events that have occurred over the course of about a billion years of evolution.

I'm here & I'm not going away: World's Oldest Bacteria Found Living In Permafrost

Finding: A research team has for the first time ever discovered DNA from living bacteria that are more than half a million years old. Never before has traces of still living organisms that old been found.

What significance does this have?

The exceptional discovery can lead to a better understanding of the aging of cells and might even cast light on the question of life on Mars. All cells decompose with time. But some cells are better than others to postpone the decomposing and thus delay aging and eventually death. And there are even organisms that are capable of regenerate and thereby repair damaged cells. The DNA of these cells are very interesting to the understanding of the process of how cells break down and age.

How the discovery was made

The research team, which consists of experts in, among other things, DNA traces in sediments and organisms, have found ancient bacteria that still contains active and living DNA. So far, it is the oldest finding of organisms containing active DNA and thus life on this earth. The discovery was made after excavations of layers of permafrost in the north-western Canada, the north-eastern Siberia and Antarctica.

Near Death
The project is about examining how bacteria can live after having been frozen down for millions of years. Other researchers has tried to uncover the life of the past and the following evolutionary development by focusing on cells that are in a state of dead-like lethargy.

Still active
We, on the other hand, have found a method that makes is possible to extract and isolate DNA traces from cells that are still active. It gives a more precise picture of the past life and the evolution towards the present because we are dealing with cells that still have a metabolistic function -- unlike "dead" cells where that function has ceased.

After the fieldwork and the isolation of the DNA, the researchers compared the DNA to DNA from a worldwide gene-bank in the US to identify the ancient material. Much in the same way the police compares fingerprints from a crime, the researchers were able to place the DNA more precisely and to place it in a context.

Impact on Darwinian evolution
There is a very long way, of course, from our basic research towards understanding why some cells can become that old. But it is interesting in this context to look at how cells break down and are restored and thus are kept over a very long period. The researchers' methods and results can be used to determine if there was ever life on Mars the way we perceive life on earth.
And then there is the grand perspective in relation to Darwin's evolution theory. It predicts that life never returns to the same genetic level. "But our findings allows us to post the question: are we dealing with a circular evolution where development, so to speak, bites its own tail if and when ancient DNA are mixed with new?

DNA and Genome transfer from one Bacterial Species to Another

Scientists are now able to take the genetic material from one bacterial species and transfer it to another, basically swapping their Genomes. The implications for synthetic custom - built bugs is astonishing.

The experiment marks the attempt to re-engineer a living cell with a view to one day developing micro-organisms that were different than how nature designed them. Some could be used for biofuels, cleaning up toxic waste, sequestering carbon or other applications.

Transplanting the entire genome from one species to another and having it work is the equivalent of taking a MacIntosh computer and making it a PC by inserting a new piece of software.

For the first time it is possible to insert an intact genome into a host organism and have that second organism express the original-foreign DNA.

But what is next? To create a synthetic genome and then transplant that one into a host organism.

From an evolutionary perspective, it would indicate that if man could do something like this, it would be possible for it to also occur in nature. In other words, the variation that we see in nature, may have come about with the co-mingling of genomes from different species.

The Tree of Life: Archaea, Bacteria, and Eukaryota

If we are to talk about evolution, then we first have to talk about what kind of life exists on earth. The tree of life is made up of three distinct branches. The Eukaryota, Bacteria, and Archaea.

Eukaryotes
The eukaryotes include animals (humans), plants and fungi and a rich variety of micro-organisms also known as protists. The protists include parasites which can be biologically speaking very successful and they can compromise the environment of entire countries. The Eukaryotes are identified and distinguished from other forms of life by the presence of nuclei and the presence of a cytoskeleton.


Bacteria
Bacteria are microscopic organisms whose single cells do not have a membrane-bounded nucleus nor other membrane-bounded organelles like mitochondria and chloroplasts. Another group of microbes, the archaea, meet these criteria but are so different from the bacteria in other ways that they must have had a long, independent evolutionary history since close to the dawn of life.

Bacteria are maligned because of the human and animal disease they cause. However, some, like the actinomycetes, produce antibiotics such as streptomycin and nocardicin. Others have different functions. They live symbiotically in the guts of animals (including humans) or elsewhere in their bodies, or on the roots of certain plants, converting nitrogen into a usable form. They are seen everywhere. For instance, bacteria give the tangy taste in yogurt and the sour in sourdough bread. Bacteria are responsible for the break down of dead organic matter. The are also an important base of the food web in many environments. Life on earth may be complex but it appears that this was the basis of all early life. The oldest fossils known, nearly 3.5 billion years old, are fossils of bacteria-like organisms.

Archaea
Archaea are microbes and most live in extreme environments. Those that do are called extremophyles. Other Archaea species are not extremophiles and live in ordinary temperatures and salinities.

When these microscopic organisms were first discovered in 1977, they were considered bacteria. It became apparent however, that they were not when their ribosomal RNA was sequenced. The sequencing showed that they were not closely relationed to the bacteria but were instead more closely related to the eukaryotes.

Archaea are a much different and simpler form of life. They may also be the oldest form of life on Earth. Because they requires neither sunlight for photosynthesis as do plants, nor oxygen as to animals. Archaea absorbs CO2, N2, or H2S and gives off methane gas as a waste product the same way humans breathe in oxygen and breathe out carbon dioxide.

Archaeans may be the only organisms that can live in extreme habitats such as extremely hot thermal vents or hypersaline water. They appear to be extremely abundant in environments that are hostile to all other life forms.