Lactobacillus hamsteri was first studied and mentioned by Fujisawa and Mitsouka in 1988.

What is Lactobacillus hamsteri?

  1. hamsteri is a species of bacteria belonging to the Lactobacillus family. It is classified as such because it is a facultative anaerobe, meaning it can survive even in the absence of oxygen. It also shares the same physiological and morphological characteristics as those of other lactobacillus species.

Significant characteristics of L.hamsteri:

  • It is non-spore forming.
  • It is non-motile.
  • It is rod-shaped.
  • It is a Gram-positive bacterial species.
  • The major by-product of glucose fermentation in the case of this bacterial species is lactic acid.
  • It sometimes occurs in the form of chains but most of the time it occurs singly.

Lactobacillaceae art

Electron microscope image of Lactobacillus spp.

The Lactobacillus family:

Bacteria belonging to this genus are usually found in the microbiota of all humans and most animals. These bacteria are known as “good” or probiotic bacteria and are usually non-pathogenic. They are usually found in the gastrointestinal and urogenital tracts of humans and help to maintain the pH and balance of these mucosal-lined tracts.

Lactobacillus bacteria usually produce slime-like films which protect them from the harsh environment of the gut and help them survive the highly acidic environment of the gastrointestinal and urogenital tracts. They are defined as facultative anaerobes as they can survive even in the absence of oxygen. Their main metabolic by-product is lactic acid, hence the name Lactobacillus. Such bacterial species are rod-shaped and non-spore forming, reducing their pathogenicity. They are also non-motile. All Lactobacillus species are Gram-positive.

Where is it found?

Lactobacillus hamsteri is found in the intestinal flora of adult hamsters. Hamsters, now commonly identified as house pets, belong to the order Rodentia and are also known as rodents. 

They can be classified as nocturnal. They are omnivorous and can live on a diet of both meat and vegetables. Hence, they possess a very varied gut microflora. They are also classified as hind-gut fermenters.

The evolution of hamsters can be dated back to 15.2 million years ago via the study of fossils of 15 genera. Hamsters are small-bodied rodents with stout noses and tails that are considerably shorter than their body length. They have wide feet and short legs and are characterised by the presence of pointed ears. They are generally solitary animals.

Hamsters- diet, habits and types

A hamster in the wild

Culturing of Lactobacillus hamsteri:

The intestinal flora of hamsters can be studied by isolating various bacterial species from their faecal matter. Out of 91 species, 83 have been isolated and identified. Lactobacillus hamsteri was also isolated similarly, via the following steps-

  • The collected faecal matter must be emulsified in an anaerobic buffer and then solubilised in it.
  • The solution must then be cultured on a glucose-blood-liver agar plate.
  • The plate must be incubated at room temperature for 2 days (while being kept in a steel-wool covered jar.
  • It is important to note that the agar plate must be kept in a carbon dioxide-rich environment.

Characteristics of the isolated culture:

  • 0.7 – 3.0 mm in diameter- this can be observed using a microscope and a millimetre scale.
  • Umbonate- this refers to the presence of a protuberance near the edges of the colony.
  • Brown colouration- the pigments present in bacterial colonies are usually checked for their solubility in water.
  • Singly produced- this refers to the production of the bacterium individually, it is usually present as a single cell and not in pairs.
  • Rough profile- the elevation of the culture is such that the texture of the colony seems rough.
  • Irregular edges- the edges of the observed colony are not regular.
  • Opaque and round the observed colony is not transparent and does not irradiate any light unlike iridescent colonies

Culture Media


Blood-Liver agar


Not much is still known about this isolated bacterial species, however as it belongs to the Lactobacillus family it can be hypothesised that it might possess probiotic and cholesterol mitigating properties that other Lactobacilli possess.

In hamsters, these bacterial species maintain the pH and chemical balance of the gut, such a dynamic can be classified as a symbiotic interaction. This species is in no way harmful to the host organism and is beneficial in the sense that it improves digestion and gut health.

Deepika Thilakan


Tags: Lactobacillus hamsteri

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