Candidatus Carsonella ruddii facts for kids

"Candidatus Carsonella ruddii" is a very tiny type of bacteria. It must live inside other living things. Scientists call this an obligate endosymbiotic Gammaproteobacterium. It has one of the smallest genomes (its complete set of DNA) of any known bacteria.

This bacteria is the first species found in the genus Candidatus Carsonella. It was named after Rachel Carson, a famous scientist. As of February 2022, it is still the only species described in this group.

What is Endosymbiosis?

Candidatus Carsonella ruddii is an endosymbiont. This means it lives inside another organism. You can find this bacteria in all types of psyllids. Psyllids are small insects that feed on plant sap.

The bacteria live in a special part of the insect's body. This part is called a bacteriome.

How do they help each other?

C. ruddii is not completely harmful to its host insect. It actually helps the insect by giving it important amino acids. These are like building blocks for proteins.

Scientists think this bacteria might be changing over time. It could be becoming like an organelle. An organelle is a tiny part inside a cell that does a specific job. A good example is the mitochondria in our own cells. Mitochondria also started as bacteria living inside other cells a long, long time ago.

Discovering its Tiny Genome

A genome is all the genetic information of an organism. It's like a complete instruction manual for life. In 2006, scientists studied the genome of Ca. C. ruddii. They looked at a specific type found in the hackberry petiole gall psyllid. This insect is called Pachypsylla venusta.

How small is its genome?

Scientists at RIKEN in Japan and the University of Arizona studied its genome. They found it has a circular chromosome with 159,662 base pairs. Base pairs are the basic units of DNA.

This bacteria's genome is very compact. About 97% of it contains instructions for making things. Many of its genes (parts of the DNA that carry specific instructions) overlap. The genes themselves are also very short.

It has only 182 predicted genes. This was the lowest number ever found at the time. For comparison, Mycoplasma genitalium has 521 genes. That bacteria has the smallest genome of any organism that can live on its own.

What's missing?

Many genes that are usually needed for life seem to be missing in C. ruddii. This suggests that the bacteria might be becoming more like an organelle. This means it relies heavily on its host for many basic life functions.

When its genome was first studied, C. ruddii was thought to have the smallest bacterial genome. Now, another bacteria called Nasuia deltocephalinicola is known to have an even smaller one. Its genome is only 112,000 base pairs long.

C. ruddii and similar bacteria seem to be losing genes over time. This process is called genomic reduction.

See also

In Spanish: Candidatus Carsonella ruddii para niños