Lactobacillus Bulgaricus: Characteristics, Morphology, Benefits

Lactobacillus bulgaricus  is a species of bacteria belonging to the group called lactic bacilli, with probiotic activity. It has very peculiar characteristics, since it establishes symbiotic associations with yeasts and forms conglomerates that can vary in appearance. FIt was discovered by Dr. Stamen Grigorov in 1905 when he was still a student.

Lactobacillus bulgaricus and Streptococcus thermophilus were the first known bacteria with probiotic activity, being used for the fermentation of sheep’s milk and obtaining yogurt, cheese, among other products.

Today L. bulgaricus is one of the main probiotics at the food industry level, which is used for the preservation and development of the organoleptic characteristics of processed products such as taste, smell and texture.

These microorganisms, along with other probiotics, can be found in tablets, powders, or incorporated into various foods such as milk and its fermented derivatives, chewable gums, sweets, desserts, drinks, soy-based preparations, among others.


Lactobacillus bulgaricus does not form spores and is nonmotile . They are acidophilic microorganisms, since they require a low pH in order to grow and develop (pH between 5.4 to 4.6).

It is a thermophilic bacterium, that is, the temperature range for its growth ranges from 45  o C to 115  o C

It does not have a capsule, but the industry has tried to create an artificial capsule of alginate plus denatured whey proteins to protect probiotics from environmental changes and thus give it greater viability within the body.


This bacterium is native to Bulgaria. Therefore, it is found in the gastrointestinal tract of mammals from that locality.

Meanwhile, a specific strain (GLB44) has been isolated from vegetables in the same country, specifically from the leaves of Galanthus nivalis ( snowdrop flower).

Features that make it ideal for the industry

It is used in industry as starters for a large number of foods, for example yogurts. In this sense, it acts synergistically with Streptococous thermophilus.

The two species work together to form lactic acid, which gives yogurt a pleasantly sour taste.

The acidic pH works as a preservative, since under this pH very few bacteria can grow, in addition this causes the milk proteins to coagulate, which gives it the perfect consistency of yogurt.

During this process, acetaldehyde is also formed, which gives it the characteristic aroma of yogurt, along with other compounds. In the production of yogurt, this microorganism is crucial especially in the post acidification stage.

Some strains, such as the one isolated from plants ( L. bulgaricus GLB44) are capable of eliminating certain bacteria in vitro , thanks to the production of bacteriocins.

Consuming yogurt causes the intestine to be seeded with beneficial bacteria and thus displaces certain bacteria such as Clostridium.

These are bacteria of the intestine that have proteolytic activity, being responsible for the production of toxic substances such as phenols, ammonia and indoles by the digestion of protein. These substances seem to contribute to the aging of cells.


Domain: Bacteria

Division: Firmicutes

Class: Bacilli

Order: Lactobacillales

Family: Lactobacillaceae

Genus: Lactobacillus

Species: delbrueckii

Subspecies : bulgaricus.


They are Gram positive rods that are characterized by being long, and sometimes form filaments.

The Lactobacillus bulgaricus have a structurally complex, as they may be presented in 3 different ways: laminar and convolute wound.

The conglomerates in general are elastic and yellowish-white in color.

The laminar shape is so called because it has two surfaces, one smooth and one rough. The first is characterized by the presence of short bacilli and the second by yeast. Between both layers an intermediate layer can be distinguished where both converge.

The convolute form has three layers: outer, middle, and inner.

Short lactobacilli abound on the outside. The stocking has a variety of shapes, including long straight lactobacilli, long curved lactobacilli, and some yeasts. The internal one presents lactobacilli and abundant yeasts intermixed in a cavernous matrix. Filamentous lactobacilli abound in the curly one.


Health benefits

The consumption of foods that contain probiotics provide special protection in diarrhea associated with antibiotics, Rotavirus and Clostridium difficile diarrhea in children and adults.

It has also been seen to be able to reduce the symptoms of irritable bowel syndrome, ulcerative colitis, and is involved in the prevention of necrotizing enterocolitis.

Likewise, this bacterium during the fermentation process produces short chain fatty acids that give energy, which contributes to the production of digestive enzymes. These help the absorption of metabolites such as essential vitamins and minerals.

On the other hand, there is evidence that it may have a beneficial effect on obesity and insulin resistance, although it is not scientifically proven.

They are useful in patients suffering from lactose intolerance. Yogurt with probiotics contains the enzyme that is deficient in these patients, namely lactase (Beta-galactosidase).

Likewise, it favors the decrease of harmful metabolites such as ammonium and procancerogenic enzymes in the colon.

It modulates the immune response, increasing the secretion of immunoglobulin A as a protective barrier and stimulates the production of cytokines that lead to the activation of local macrophages.

It also reduces allergic reactions to food.

Finally, it has been suggested that the consumption of foods with L. bulgaricus may have a role in the normalization of blood hypertension, due to the presence of inhibitor peptides of the angiotensin-converting enzyme I produced in the fermentation of dairy products with probiotics.

Benefits for the environment

Currently, other uses are being sought for Lactobacilus bulgaricus together with Streptococcus thermophilus and some fungi for the conservation of the environment, especially for the protection of water sources.

Cheese industries dispose of a toxic waste product for the environment called whey, polluting the waters. After much research, it has been seen that these microorganisms can be used to transform whey.

It serves as a raw material to obtain lactic acid useful for making food, chemical, cosmetic and pharmaceutical products. Also lactic acid can be used to produce a biopolymer called poly lactic acid (PLA).

This material is biodegradable, biocompatible, friendly to the environment and could replace plastics derived from the petrochemical industry.


  1. Wikipedia contributors. Lactobacillus delbrueckii subsp. bulgaricus . Wikipedia, The Free Encyclopedia. August 8, 2018, 15:16 UTC. Available at:
  2. Vázquez C, Botella-Carretero J., García-Albiach R, Pozuelo M, Rodríguez-Baños M, Baquero F, et al. Screening in a Lactobacillus delbrueckii subsp. bulgaricus Collection to select a strain able to survive to the human intestinal tract. Nutr. Hosp.   2013; 28 (4): 1227-1235. Available in: scielo .
  3. Rojas A, Montaño L, and Bastidas M. Production of lactic acid from whey using Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus.  Colombian Journal of Chemistry , 2015; 44 (3), 5-10. Available at:
  4. Meng-Yan Ch, Wei Z, Qiu-Yue D, Zhen-Hua L, Lu-E S, Zhen-Xing T. Activity of encapsulated Lactobacillus bulgaricus in alginate-whey protein microspheres. Braz. arch. biol. technol.   2014; 57 (5): 736-741. Available from:
  5. Stamatova I, Meurman JH, Kari K, Tervahartiala T, Sorsa T, Baltadjieva M. Safety issues of Lactobacillus bulgaricus with respect to human gelatinases in vitro. FEMS Immunol Med Microbiol . 2007; 51 (1): 194-200.

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