Buchnera aphidicola

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A Microbial Biorealm page on the genus Buchnera aphidicola

Classification

Higher order taxa:

Kingdom: Bacteria

Phylum: Proteobacteria

Class: Gamma Proteobacteria

Order: Enterobacteriales

Family: Enterobacteriaceae Genus: Buchnera Species: B. aphidicola

Species:

Buchnera aphidicola

Description and Significance

Buchnera aphidicola a member of the Proteobacteria, is the primary endosymbiont of aphids (A. pisum). It is believed that Buchnera was once a free living gram negative ancestor similar to a modern Enterobacteriaceae such as Escherichia coli. Buchnera are 3 µm in diameter and have some of the key characteristics of their Enterobacteriaceae relatives such as a gram-negative cell wall. However, unlike most other gram-negative bacteria, Buchnera lack the genes to produce lipopolysaccharides (LPS) for their outer membrane.

Genome Structure

Buchnera aphidicola has not only one of the smallest known genomes of any living organism, it is also one of the most genetically stable due to the lack of many enzymes involved in metabolisms.

Cell Structure and Metabolism

The long association with aphids and the lack of crossover events due to vertical transmission of genetic materials within its species has caused the deletion of genes required for anaerobic respiration, the synthesis of amino-sugars, fatty acids, phospholipids, and complex carbohydrates. Buchnera also have lost regulatory factors allowing continuous overproduction of tryptophan and other amino acids.

Ecology

The symbiotic relationship with aphids began between 200 million and 150 million years ago, and has persisted through maternal transmission and co-speciation. Aphids have developed bacteriocyte cells to house Buchnera. It is estimated that a mature aphid may carry 5.6 × 10^6 Buchnera cells. Each bacteriocyte contains multiple vesicles, symbiosomes derived from the plasma membrane.

Current Research

Buchnera was first named by Paul Baumann and his graduate student, as well as the first molecular characterization of a symbiotic bacterium using Buchnera. The studies on Buchnera later contributed to many studies on symbionts of many groups of insects, pursued by numerous investigators like Paul and Linda Baumann, Nancy Moran, Serap Aksoy, Roy Gross, who co-investigated symbionts of aphids, tsetse flies, ants, leafhoppers, mealybugs, whiteflies, psyllids, etc.

References

Pérez-Brocal V, Gil R, Ramos S, Lamelas A, Postigo M, Michelena J, Silva F, Moya A, Latorre A (2006). "A small microbial genome: the end of a long symbiotic relationship?". Science 314 (5797): 312-3. PMID 17038625.

Edited by Kyu Hahn student of Rachel Larsen and Kit Pogliano