Mycoplasma laboratorium facts for kids
Mycoplasma laboratorium or Synthia is a special kind of bacterium created using synthetic biology. Imagine building a living thing from scratch! That's what scientists aimed to do with Synthia.
The project started with a big question: What are the fewest genes needed for life? Scientists first looked at a bacterium called Mycoplasma genitalium because it had very few genes. Their goal was to find the absolute minimum genes required for it to survive and then build those genes in the lab to create a "new" organism.
Later, the focus shifted to another bacterium, Mycoplasma mycoides, because it grew faster, which helped speed up experiments. In 2010, scientists successfully built the entire set of genes for M. mycoides from a computer design. They then put these synthetic genes into an existing cell of Mycoplasma capricolum that had its own DNA removed. This new bacterium could grow and was named JCVI-syn1.0, or Synthia.
After more experiments, a even smaller version, JCVI-syn3.0, was made. It has only 473 genes, and interestingly, scientists still don't know what 149 of those genes do! Because the genes of JCVI-syn3.0 were completely new and designed, it's considered the first truly synthetic organism.
Contents
The Minimal Genome Project
The creation of Synthia was part of a big effort called the Minimal Genome Project. It took place at the J. Craig Venter Institute and involved about 20 scientists. Key researchers included Nobel laureate Hamilton O. Smith, DNA expert Craig Venter, and microbiologist Clyde A. Hutchison III.
Their main goal was to understand life at its most basic level. They wanted to find out what is absolutely necessary to build a living organism from scratch. They started by studying M. genitalium, which at the time had the smallest known genome (all its genes) of any free-living organism. They carefully removed genes one by one to see which ones were essential for the bacterium to live and grow. This helped them find a core set of 382 genes they thought were the minimum needed for life.
Why Mycoplasma?
What is Mycoplasma?
Mycoplasma is a type of bacteria that's special because it doesn't have a cell wall. Most bacteria have a cell wall, which gives them shape and protection. Because Mycoplasma lacks this wall, it's often a parasite (living off another organism) or a commensal (living with another organism without harming it).
Scientists are very interested in Mycoplasma. It can be a tricky contaminant in lab experiments because it's hard to get rid of. But its small genome size also makes it a great "model organism" for studying life, which is why it was chosen for the Synthia project. The idea of using Mycoplasma for this kind of work goes back to 2000, when the name Mycoplasma laboratorium was first suggested.
Other Small Organisms
While M. genitalium was chosen for its small genome, other organisms have even smaller ones. For example, Pelagibacter ubique has the smallest known genome of any free-living organism. It's also one of the most common bacteria in the ocean!
Some other tiny organisms, like Hodgkinia cicadicola and Carsonella ruddi, have even fewer genes than M. genitalium. However, these organisms are not free-living; they depend on other creatures (like cicadas) to survive. This means their hosts might provide some of the essential genes they are missing. The organism with the smallest known set of genes is Nasuia deltocephalinicola, which has only 137 genes.
How Synthia Was Made
To create Synthia, scientists had to invent or improve several complex lab methods. They needed ways to build and move very large pieces of DNA.
Moving Bacterial Genomes
In 2007, the team figured out how to move the entire set of genes (the chromosome) from one type of Mycoplasma to another. They took the genes from Mycoplasma mycoides and put them into Mycoplasma capricolum cells that had their own DNA removed.
Here's a simplified idea of how they did it:
- They carefully took out the genes from M. mycoides cells.
- They prepared the M. capricolum cells to be ready to accept new DNA.
- They used a special chemical to help the M. mycoides genes enter the M. capricolum cells.
This process is like a "genome transplant," similar to how doctors might transplant an organ.
Building Bacterial Chromosomes
In 2008, the team described how they built a synthetic genome, which was a copy of M. genitalium's genes. They used a step-by-step process:
- Small Pieces: First, they synthesized the genome in many small pieces, each about 1,000 DNA building blocks long.
- Joining Pieces: Then, they joined these small pieces together to make larger sections, about 10,000 building blocks long. They did this inside E. coli bacteria.
- Even Bigger Pieces: Next, they combined these 10,000-block sections to create even larger parts, about 100,000 building blocks long. They grew these in yeast.
- Final Assembly: Finally, they took all these big pieces, joined them, and put them into yeast cells.
This careful, step-by-step method allowed them to build a complete set of genes from scratch.
The Synthetic Genome
In 2010, Venter's team successfully created Mycoplasma mycoides strain JCVI-syn1.0 with a completely synthetic genome. At first, the synthetic genes didn't work. It took three months to find the problem: a tiny mistake in just one gene! Fixing this mistake made the synthetic organism functional.
The main reason for building a cell with synthetic genes was to test their methods. They wanted to see if they could truly build a living thing from a computer design. While the genes were made in the lab, they were put into a natural cell that already had all the necessary proteins and other parts. Some people debated if this was a "true" synthetic organism, since it still relied on parts from a natural cell.
Hidden Messages (Watermarks)
One cool thing about JCVI-syn1.0 is that it has secret messages hidden in its DNA! These are called "watermarks." The scientists wrote four different messages into the DNA sequence. They used a special code, not the usual genetic code that cells use to make proteins. They even challenged people to figure out their secret code!
Here's what the hidden messages said:
- Message 1: A message congratulating whoever decoded it and instructions on how to email the scientists.
- Message 2: A list of the scientists who worked on the project and a quote from writer James Joyce: "To live, to err, to fall, to triumph, to recreate life out of life."
- Message 3: More scientists' names and a quote from Robert Oppenheimer: "See things not as they are, but as they might be."
- Message 4: Even more scientists' names and a quote from physicist Richard Feynman: "What I cannot build, I cannot understand."
JCVI-syn3.0
In 2016, the Venter Institute created an even smaller synthetic organism called JCVI-syn3.0. They used genes from JCVI-syn1.0 to make a genome with only 531,560 DNA building blocks and 473 genes.
Back in 1996, some scientists thought that a living cell might need only about 256 genes to survive. But with JCVI-syn3.0, the scientists found they needed 473 genes. What's really interesting is that about 149 of these genes have functions that are still completely unknown! By 2022, they narrowed this down to about 100 unknown genes. In 2019, scientists even created a full computer model of how all the parts of a Syn3.0 cell work together.
