Lactobacillus delbrueckii belonging to the Lactobacillus genre, functions as a probiotic bacteria found in the gastrointestinal tract.  

Green colored rod-shaped structures attached to each other

Lactobacillus species are known as good bacteria for their probiotic role in the gastrointestinal tract of humans and animals. This genre is also found in genital areas, the urinary bladder, and other human body parts. The primary function of the lactobacillus species is to prevent the growth of harmful pathogens in the body that causes diseases, regulate immunomodulation, and increase nutrient absorption in the gastrointestinal tract. Lactobacillus delbrueckii has four subspecies; subsp. lactis, subsp. indicus, subsp. bulgaricus, and subsp. delbrueckii. These species are used in the fermentation of dairy products for flavor and texture; therefore, they are utilized in the food industry. They also contain probiotic characteristics in blocking foodborne pathogens from activating. Thus, the lactobacillus species are incorporated into the diet to maintain the microbiota of the human gastrointestinal tract. 

Lactobacillus delbrueckii has four subspecies; L. delbrueckii subsp. lactis, L. delbrueckii subsp. indicus, L. delbrueckii subsp. bulgaricus, and L. delbrueckii subsp. delbrueckii.  These are short or single chained rod-shaped, gram-positive, non-motile, non-spore forming bacteria. They are homofermentative as they produce D(-) lactic acid from carbohydrates. These species are microaerophilic as they can thrive under low oxygen levels. The optimal growth of the Lactobacillus delbrueckii group in milk is observed between 40-45°C. The GC content of their DNA ranges from 49 to 51 mol%. L. delbrueckii subsp. lactis aids in maintaining the flora in the gastrointestinal tract, preventing infections in the urogenital system, and controlling the growth of enteric pathogens in the gastrointestinal tract. L. delbrueckii subsp. indicus is also used to ferment dairy products. 

Orange colored glowing lines

delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis are capable of fermenting lactose used in cheese production by generating bacteriocins. However, L. delbrueckii subsp. delbrueckii are incapable of fermenting lactose and are not utilized in dairy products as a starter. L. delbrueckii subsp. bulgaricus is utilized in association with the growth of Streptococcus thermophilus, primarily to manufacture yogurt. From this association, acetaldehyde is produced, which provides flavor to the yogurt of all these four subspecies of Lactobacillus delbrueckii, L. delbrueckii subsp. Bulgaricus has been majorly used as a starter in fermented products. 


Lactobacillus delbrueckii subsp. bulgaricus is utilized as a starter in most dairy products and yogurt. While, L. delbrueckii subsp. lactis species is in the manufacture of different types of cheeses. These two species are differentiated by their ability to metabolize other carbohydrates, especially with various glucose substrates. Therefore the subspecies of Lactobacillus delbrueckii are utilized in the dairy food industry. Lactobacillus delbrueckii subsp. bulgaricus has been studied to have probiotic effects in the human body against pathogens. They have been observed to have anti-inflammatory characteristics by this subspecies. Furthermore, Lactobacillus delbrueckii subsp. bulgaricus was found to have tolerance against foodborne pathogens such as; Staphylococcus aureus and Escherichia coli at low pH. However, at pH 6.5 and 7, the subsp. bulgaricus tolerance against these two pathogens is observed to have reduced. Therefore, this lactobacillus subspecies has been determined to contain anti-inflammatory, anti-microbial, bile and acid tolerance, and lipid-regulating properties. 

Grey colored thin rod-shaped structures

As these subspecies have probiotic properties, they are incorporated into the healthy diet in the form of industrially produced yogurt, milk drinks, and other food products. Furthermore, yogurt products containing Lactobacillus species have been observed to alleviate symptoms caused by bacterial vaginosis in females. L. delbrueckii subsp. bulgaricus has been shown to mitigate lead toxicity induced for treatment and prevention in vivo. Moreover, they are capable of producing increased amounts of organic acids such as; lactic acid and acetic acid, which can suppress the pathogens in vitro and enhance the immunity system and avoid organ damage. Therefore, Lactobacillus delbrueckii species and its subspecies are applied in the food industry as they contain probiotic properties against disease-causing foodborne pathogens. 

Tags: microbe

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