Candidatus

Overview of the term "Candidatus" in microbiology

Candidatus is a term used in microbiology to denote a provisional status for a bacterium or other microorganism that has been detected and described but not yet cultured in a laboratory setting. This term is used to acknowledge the existence of these organisms based on molecular and genetic evidence, even though they have not been isolated in pure culture.

Overview

The term "Candidatus" is applied to microorganisms that are known primarily through DNA sequencing and other indirect methods. These organisms often belong to groups that are difficult to culture using traditional laboratory techniques. The use of "Candidatus" allows scientists to communicate about these organisms and their potential roles in various environments, even when full taxonomic classification is not possible.

The concept of "Candidatus" was introduced to address the limitations of the International Code of Nomenclature of Bacteria, which traditionally required a pure culture for the valid publication of a new bacterial name. By using "Candidatus," researchers can describe and name organisms that are significant in their ecological niches or have potential medical importance.

Examples

One well-known example of a "Candidatus" organism is Candidatus Pelagibacter ubique, a member of the SAR11 clade, which is one of the most abundant groups of bacteria in the ocean. Another example is Candidatus Liberibacter, which includes species associated with plant diseases such as citrus greening disease.

Significance

The "Candidatus" designation is crucial for advancing our understanding of microbial diversity and ecology. It allows researchers to study the genetic and functional characteristics of these organisms, providing insights into their roles in various ecosystems, including human health and disease.

Challenges

One of the main challenges with "Candidatus" organisms is the difficulty in obtaining pure cultures, which limits the ability to perform traditional microbiological studies. Advances in metagenomics and single-cell genomics are helping to overcome these challenges by providing more detailed information about the genomes and potential functions of these uncultured organisms.

Also see

• Microbial ecology
• Metagenomics
• Bacterial taxonomy
• Uncultured microorganism