Lactobacillus bulgaricus is a probiotic bacterium primarily used in the production of yogurt. This bacterium ferments lactose, the sugar in milk, producing lactic acid which helps coagulate milk proteins, giving yogurt its characteristic texture and tanginess. 

The name describes the structure of the molecule:

• Lactobacillus is a genus of bacteria that are part of the lactobacilli family. They are known for their ability to convert sugars into lactic acid, a process that makes them crucial in milk fermentation and other food fermentations.
• bulgaricus indicates the Bulgarian origin of this particular strain. The name refers to Bulgaria, where these bacteria were extensively studied and are central to the production of traditional Bulgarian yogurt.

Industrial Production Process

• Strain selection. The process begins with the selection of a pure strain of Lactobacillus bulgaricus that exhibits optimal characteristics for dairy product fermentation.
• Culture medium preparation. A specific culture medium is prepared, enriched with nutrients such as peptones, meat extracts, and lactose, to support bacterial growth.
• Fermentation. The selected strain is inoculated into sterile fermenters where fermentation takes place under controlled conditions of temperature (generally between 37°C and 45°C), pH, and anaerobiosis.
• Growth monitoring. During fermentation, bacterial growth is continuously monitored to ensure optimal conditions and prevent contamination.
• Bacteria harvesting. Once fermentation is complete and the desired cell count is achieved, the bacteria are harvested via centrifugation.
• Stabilization. The bacteria can be stabilized through lyophilization or freezing processes to preserve vitality and facilitate transport and storage.
• Formulation. The final product can be formulated as a dry or frozen starter culture, ready to be used in the production of yogurt and other dairy products.
• Quality control. Each batch produced undergoes rigorous quality control to ensure vitality, purity, and effectiveness in lactic fermentation.

What it is used for and where

Lactobacillus bulgaricus is known for its health-promoting properties, including promoting a healthy balance of gut flora. It is particularly effective in aiding lactose digestion, which can be beneficial for people with lactose intolerance. It is also associated with improved immunity and potential positive effects on reducing cholesterol.

Lactobacillus bulgaricus is a type of lactic acid bacteria that plays a key role in the production of yogurt and other fermented dairy products. It is particularly known for its benefits to intestinal health (1) and its ability to enhance the properties of fermented products. Here are some of the main uses and benefits of Lactobacillus bulgaricus.

Yogurt Production. Lactobacillus bulgaricus is one of the primary bacteria used in the production of yogurt, contributing to its distinctive taste and texture (2).

Digestive Health. It promotes a healthy balance of intestinal flora and can help improve overall digestion, especially lactose digestion, making it beneficial for people with lactose intolerance.

Probiotic Properties. It supports gut health and boosts the immune system by stimulating antibody production and enhancing resistance to intestinal infections.

Improvement of Sensory Properties. It contributes to the pleasant flavor and texture of yogurt and other fermented products, making them tasty and appealing.

Lactic Acid Production. It produces lactic acid which helps inhibit the growth of pathogenic bacteria, improving food safety and preservation (3).

Availability. It is available in the form of starter cultures for home yogurt production and in probiotic supplements, offering an easy and accessible way to incorporate this probiotic into the diet.

References_____________________________________________________________________

(1) Takamura T, Harama D, Fukumoto S, Nakamura Y, Shimokawa N, Ishimaru K, Ikegami S, Makino S, Kitamura M, Nakao A. Lactobacillus bulgaricus OLL1181 activates the aryl hydrocarbon receptor pathway and inhibits colitis. Immunol Cell Biol. 2011 Oct;89(7):817-22. doi: 10.1038/icb.2010.165. 

Abstract. Increasing evidence suggests that the aryl hydrocarbon receptor (AhR) pathway has an important role in the regulation of inflammatory responses. Most recently, we have shown that the activation of the AhR pathway by a potent AhR agonist inhibits the development of dextran sodium sulfate (DSS)-induced colitis, a model of human ulcerative colitis, by the induction of prostaglandin E2 (PGE2) in the large intestine. Because several strains of probiotic lactic acid bacteria have been reported to inhibit DSS-induced colitis by unidentified mechanisms, we hypothesized that particular strains of lactic acid bacterium might have the potential to activate the AhR pathway, thereby inhibiting DSS-induced colitis. This study investigated whether there are specific lactic acid bacterial strains that can activate the AhR pathway, and if so, whether this AhR-activating potential is associated with suppression of DSS-induced colitis. By using AhR signaling reporter cells, we found that Lactobacillus bulgaricus OLL1181 had the potential to activate the AhR pathway. OLL1181 also induced the mRNA expression of cytochrome P450 family 1A1 (CYP1A1), a target gene of the AhR pathway, in human colon cells, which was inhibited by the addition of an AhR antagonist, α-naphthoflavon (αNF). In addition, mice treated orally with OLL1181 showed an increase in CYP1A1 mRNA expression in the large intestine and amelioration of DSS-induced colitis. Thus, OLL1181 can induce activation of the intestinal AhR pathway and inhibit DSS-induced colitis in mice. This strain of lactic acid bacterium has therefore the potential to activate the AhR pathway, which may be able to suppress colitis.

(2) Guarner F, Perdigon G, Corthier G, Salminen S, Koletzko B, Morelli L. Should yoghurt cultures be considered probiotic? Br J Nutr. 2005 Jun;93(6):783-6. doi: 10.1079/bjn20051428. 

Abstract. Probiotics are live micro-organisms that when administered in adequate amounts confer a health benefit on the host. Consumption of yoghurt has been shown to induce measurable health benefits linked to the presence of live bacteria. A number of human studies have clearly demonstrated that yoghurt containing viable bacteria (Streptococcus thermophilus and Lactobacillus delbrueckii sp. bulgaricus) improves lactose digestion and eliminates symptoms of lactose intolerance. Thus, these cultures clearly fulfil the current concept of probiotics.

(3) Yang S, Bai M, Kwok LY, Zhong Z, Sun Z. The intricate symbiotic relationship between lactic acid bacterial starters in the milk fermentation ecosystem. Crit Rev Food Sci Nutr. 2023 Nov 20:1-18. doi: 10.1080/10408398.2023.2280706.

Abstract. Fermentation is one of the most effective methods of food preservation. Since ancient times, food has been fermented using lactic acid bacteria (LAB). Fermented milk is a very intricate fermentation ecosystem, and the microbial metabolism of fermented milk largely determines its metabolic properties. The two most frequently used dairy starter strains are Streptococcus thermophilus (S. thermophilus) and Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus). To enhance both the culture growth rate and the flavor and quality of the fermented milk, it has long been customary to combine S. thermophilus and L. bulgaricus in milk fermentation due to their mutually beneficial and symbiotic relationship. On the one hand, the symbiotic relationship is reflected by the nutrient co-dependence of the two microbes at the metabolic level. On the other hand, more complex interaction mechanisms, such as quorum sensing between cells, are involved. This review summarizes the application of LAB in fermented dairy products and discusses the symbiotic mechanisms and interactions of milk LAB starter strains from the perspective of nutrient supply and intra- and interspecific quorum sensing. This review provides updated information and knowledge on microbial interactions in a fermented milk ecosystem.