Lactobacillus ultunensis is a Gram-positive bacterium. It is also mesophilic and anaerobic. It was isolated from human stomach mucosa and gastric biopsies. Lactobacillus ultunensis pertains to Ultuna, where the Swedish University of Agricultural Sciences is situated. The bacterial cells are non-spore-forming and non-motile. They are 162–30 mm in size and are catalase-negative rods. They occur as single cells, filaments, or pairs. They form colonies on MRS agar with a diameter in the range of 2–3 mm, after anaerobic growth at 37°C for 48. They are white, have a dry appearance, and are irregular. Lactobacillus ultunensis, in addition to being a beneficial organism, is a major isolate obtained from lesions in advanced dental caries. In many serious infections, it acts as a causative agent, especially in individuals who are immunocompromised and hospitalized for a long duration. The presence of the bacterium in blood specimens has gained medical importance. Bacteremia and endocarditis caused by the bacterium lead to a high mortality rate. As a potential predisposing factor, a dental condition or procedure was suggested in Lactobacillus endocarditis. In its sequenced genome, Lactobacillus ultunensis is composed of S-layer protein genes.

Shape of Lactobacillus ultunesis

SEM image of Lactobacillus ultunesis

Lactobacillus ultunesis

Schematic of Lactobacillus ultunesis


  1. Food Preservation. Another benefit of using these bacteria in food production is the  enhancement of food preservation.  The lactic acid obtained in the fermentation process increases the acidity of the food, thereby acting as a natural preservative. 
  2. Food Production. These bacteria consume sugars and produce lactic acid and other by-products that give a tangy flavor to fermented foods.  Humans had discovered a long time ago the presence of these bacteria in foods such as vegetables, fruits, milk, and in an environment where other bacteria don’t live.
  3. Health. The human gut microbiome contains these bacteria, which help in food digestion. These bacteria often act as probiotic supplements and support gut health.
  4. Medicine. In addition to supporting general health in humans, studies have shown that these bacteria actively prevent diseases such as cancer.  These bacteria reduce the risk of lymphoma and cancer of the lymph system.  Follow-up studies showed promising results on the survival of these bacteria through the human stomach to live in the intestine. 
  5. Farming. These bacteria act as biological control agents and are used to prevent bacterial and fungal diseases in crops, in addition to the availability of commercial foliar sprays.  For example, in the Korean Natural Farming method, these bacteria are collected on site and used to prevent diseases in plants caused by other organisms, thereby enhancing plant growth.


Dental caries

 Schematic of Lactobacillus ultunesis and dental caries

  1. In the initial years of a child’s life, these bacteria appear in the oral cavity. Many factors such as natural anfractuosities in the teeth, orthodontic devices, and third molars that are partly erupted lead to the growth of these bacteria. 
  2. There is a strong correlation between the bacterial count in the saliva and dental caries. Historically, these bacteria were the first microorganisms found in the development of dental caries. A large number of these bacteria are present in the saliva, mucous membranes, dorsum of the tongue, dental plaque, hard palate, tooth surfaces, etc. Fissures and pits in the oral cavity provide a favorable environment for the growth of these bacteria. 
  3. Other studies have revealed a significant correlation between the rate of these bacteria in the saliva and the smoking habit. In older patients, the bacterial rate tends to increase. Higher bacterial counts have been found in those consuming a lot of medicine and using removable prostheses. 
  4. The association between nervous breakdown and the bacterial count in the saliva has been found in a study. Therefore, there is a high risk of dental diseases among patients who are depressed. 
  5. Diet could play a major part in the correlation of these bacteria with a nervous breakdown, as patients who are depressed tend to consume a high amount of sweet products. 
  6. A large number of these bacteria in the saliva is related to xerostomia or hyposalivation. A study described the relationships between medication intake and the rate of tooth demineralization, saliva composition, saliva flow, the feeling of dry mouth, and the level of these bacteria in the saliva in adults aged 4484 years. 
  7. It was shown that patients who exhibited low unstimulated flow rates had more than 20 times bacterial counts per milliliter of saliva when compared with those who exhibited normal flow rates; especially, it was high in patients who underwent radiotherapy.

Ramya Kasinathan


Tags: Lactobacillus ultunensis

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