Gardenerella vaginalis

A Microbial Biorealm page on the genus Gardenerella vaginalis

Classification

Higher order taxa

Bacteria; Actinobacteria; Actinobacteridae; Bifidobacteriales; Bifidobacteriaceae; Gardnerella

Species

Gardnerella vaginalis

Description and significance

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.

Gardnerella vaginalis, the only species of its genus and formerly known as Haemophilus vaginalis and Corynebacterium vaginale, is a facultative anaerobic, nonmotile, pleomorphic gram-negative to gram-variable rod. It is a well-recognized colonizer of the female genital tract and survives high pH(2). It also survives poorly in human urine at 37 degrees C (3).

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Gardnerella vaginalis is a gram-variable microbe, and therefore displays both, gram-negative and gram-positive bacteria characteristics. When analyzing a culture, it may appear gram positive during the exponential growth phase but gram negative as it ages because the peptidoglycan layer becomes too thin to retain the crystal-violet iodine aggregates(5). These organisms are surrounded by a exopolysaccharide layer and pili that aid in adhering to the epithelial cells of the vagina. The cell wall is comprised of straight chain saturated and unsaturated non-hydroxylated fatty acids with hexadecanoic acid and octadecenoic acid along with major amounts of alanine, glycine, glutamic acid and lysine(4). G. vaginalis has a very complex metabolism. Gardnerella vaginalis are facultative anaerobes, which means that they can metabolism glucose (and other simple sugars) in under both aerobic and anaerobic conditions. Under the aerobic metabolism of glucose, G. vaginalis forms lactic acid and acetic acid. However, under anaerobic conditions, the metabolism of glucose yields only lactic acid.

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Gardnerella vaginalis, unlike Lactobaccilus crispatus and Lactobaccilus jensenii, is not one of the vaginal microorganisms that can survive in low pH. Lactobacillus secrete hydrogen peroxide to keep harmful organims from proliferating. Therefore, G. vaginalis requires a pH imbalance or exogenous supplements such as antibiotics, to grow.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

G. vaginalis is one of few microorganisms that cause Vaginal Bacteriosis. They are found in humans and some animals such as mares. Apart from the urinary and the bladder, they are also found in the endometrium, fetal membranes, and newborn infants and are caused by maternal infections, neonatal infections, and suppurative lesions.

Gardnerella vaginalis attaches better to urogenital squamous epithelial cells due to the exopolysaccharide layer and pili. And this attachment provides a means of migration from the vagina to the primary colonization site in the bladder. Women have squamous cells in their vagina and their bladder and these cells are absent in a man's bladder, therefore, they are less susceptible to this pathogen.

Some symptoms associated with vaginosis caused by G. vaginalis may include thin, white, yellow, homogeneous discharge with a fishy odor, clue cells on microscopy, pH of vaginal fluid greater than 4.5 (ph imbalance)(5).

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

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References

1. Joe Bischoff, Mikhail Domrachev, Scott Federhen, Carol Hotton, Detlef Leipe, Vladimir Soussov, Richard Sternberg, Sean Turner. "Gardnerella Vaginalis" <http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=2702>

2. S M Smith, T Ogbara, and R H Eng. "Involvement of Gardnerella vaginalis in urinary tract infections in men." J Clin Microbiol Volume 30. p. 1575–1577. <http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=265332>

Edited by Jaspreet Singh, student of Rachel Larsen