What is the Difference Between Lactobacillus and Lactic Acid Bacteria

The main difference between lactobacillus and lactic acid bacteria is that Lactobacillus is a rod-shaped bacterium that produces lactic acid from the fermentation of carbohydrates whereas lactic acid bacteria are either rod-shaped (bacilli) or spherical (cocci) bacteria that belong to the order Lactobacillales.

Lactobacillus and lactic acid bacteria are two types of Gram-positive bacteria that share a common metabolic pathway, which is the formation of lactic acid in their carbohydrate metabolism. 

Key Areas Covered

1. What is Lactobacillus
   • Definition, Characteristics, Metabolism
2. What are Lactic Acid Bacteria
   • Definition, Characteristics, Metabolism
3. Similarities Between Lactobacillus and Lactic Acid Bacteria
   • Outline of Common Features
4. Difference Between Lactobacillus and Lactic Acid Bacteria
   • Comparison of Key Differences

Key Terms

Lactic Acid Bacteria, Lactobacillus

What is Lactobacillus

Lactobacillus is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. It contains more than 260 species of bacteria that are phylogenetically, ecologically, and metabolically diverse.  Lactobacillus is a component of the human and animal microbiota and occurs in the digestive system and the female genital system. Lactobacillus forms biofilms in the vaginal and gut microbiota to avoid harsh environmental conditions. Moreover, the relationship between humans and Lactobacillus is mutualistic. Generally, Lactobacillus protects the human body from invading pathogens while Lactobacillus relies on nutrition from the human body. On the other hand, Lactobacillus is the most common probiotic that occurs in food and yogurt. It is diverse in its application to maintain human well-being, as it can help treat diarrhea, vaginal infections, and skin disorders such as eczema.

Figure 1: Lactobacillus near Endothelial Cell

Furthermore, Lactobacillus can be either homofermentative or heterofermentative. Here, homofermentative Lactobacillus metabolizes hexoses into the major end product, lactate, while heterofermentative Lactobacillus metabolizes hexose into lactate, carbon dioxide, and acetate or ethanol.

What is Lactic Acid Bacteria

Lactic acid bacteria are the order of bacteria in decomposing plants and milk products and produce lactic acid as the major metabolic end product of carbohydrate fermentation. It belongs to the order Lactobacillales. In addition, lactic acid bacteria are Gram-positive, low-GC, acid-tolerant, generally nonsporulating, non-respiring, either rod-shaped (bacilli) or spherical (cocci) bacteria that share common metabolic and physiological characteristics. As mentioned earlier, lactic acid bacteria are important in food fermentation and the acidification by the bacteria inhibits the growth of spoilage agents.

Figure 2: Streptococci

Moreover, some of the genera that comprise the LAB are Lactobacillus, Leuconostoc, Pediococcus, Lactococcus, and Streptococcus, as well as the more peripheral Aerococcus, Carnobacterium, Enterococcus, Oenococcus, Sporolactobacillus, Tetragenococcus, Vagococcus, and Weissella. All but Sporolactobacillus are members of the Lactobacillales order, and all are members of the Bacillota phylum.

Similarities Between Lactobacillus and Lactic Acid Bacteria

• Lactobacillus and lactic acid bacteria are two groups of bacteria that share a common metabolic process, carbohydrate fermentation into lactic acid.
• They can be rod-shaped bacteria.
• Both Lactobacillus and lactic acid bacteria include Gram-positive, low-GC, acid-tolerant, generally nonsporulating, and non-respiring.

Difference Between Lactobacillus and Lactic Acid Bacteria

Definition

Lactobacillus refers to a rod-shaped bacterium that produces lactic acid from the fermentation of carbohydrates while lactic acid bacteria refers to Gram-positive bacteria that do not form spores and are able to grow both in the presence and absence of oxygen.

Significance

Usually, Lactobacillus is a genus of the order Lactobacillales while lactic acid bacteria represent the order Lactobacillales.

Shape

Furthermore, Lactobacillus is rod-shaped while lactic acid bacteria can be either rod-shaped or cocci.

Importance

Lactobacillus occurs in the human microbiota and is important commercially in the dairy industry while lactic acid bacteria produce lactic acid as the major metabolic end product of carbohydrate fermentation.

Conclusion

In brief, Lactobacillus and lactic acid bacteria are two groups of lactic acid fermenting bacteria. Lactobacillus is a rod-shaped bacterium while lactic acid bacteria can be either rod-shaped or cocci. In addition, lactic acid bacteria belong to the order Lactobacillales. However, Lactobacillus is a part of the human microbiota and is important in food fermentation. Therefore, the main difference between Lactobacillus and lactic acid bacteria is their classification.

References:

1. Wikimedia Foundation. (2022, August 22). Lactobacillus. Wikipedia. Retrieved September 4, 2022.
2. Wikimedia Foundation. (2022, May 16). Lactic acid bacteria. Wikipedia. Retrieved September 4, 2022.

Image Courtesy:

1. “Lactobacillus sp 01” By Photo Credit: Janice Carr, Content Providers(s): CDC/Dr. Mike Miller (Public Domain) via Commons Wikimedia
2. “Streptococci ” By User:Graham Beards – Own Work  (CC BY-SA 3.0) via Commons Wikimedia