The Microbyte Series - Lactobacillus acidophilus- It's in the name!

Neha Rao

Jun 11, 2025

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4 min read

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MicroByte Series

History and naming

L. acidophilus was first isolated in 1900 from infant feces by Moro and originally named Bacillus acidophilus. The species has undergone multiple taxonomic revisions due to limitations in early methods that relied on morphology and biochemistry. Many human isolates were incorrectly labeled as L. acidophilus from 1920 to the 1970s. Phenotypic similarity among lactic acid bacteria led to frequent misidentifications and misclassifications, including strains now reclassified (e.g., L. johnsonii). Several strains with the same genetic identity have been labeled differently across culture collections and commercial uses. Despite taxonomic confusion, L. acidophilus became a widely used probiotic, particularly in dairy products like yogurt.

Feces- Poop or solid waste material excreted from the body after food has been digested and nutrients have been absorbed.

Taxonomic- Relating to taxonomy, the scientific system used to name, describe, and classify living organisms into organized groups based on shared characteristics.

Morphology- The study of the physical shape, size, structure, and external appearance of an organism or its parts (such as how a bacterium looks under a microscope).

Phenotypic similarity- When two different organisms look, function, or behave alike due to shared physical traits, even if their underlying genetics are different.

Genetic identity- The exact DNA sequence or genetic blueprint that uniquely defines a specific organism or strain.

Culture- In biology, a laboratory method of growing microbes (like bacteria or yeast) in a controlled environment, such as a Petri dish, so they can be studied.

Health benefits

Lactobacillus acidophilus exhibits several key characteristics that play an important role in maintaining overall health. Lactobacillus acidophilus guards the gut by producing acids, making the gut environment unfavourable for the growth of harmful bacteria and supporting the beneficial ones. It also plays a crucial role in strengthening the gut barrier integrity by increasing the expression of tight junction proteins and the production of protective substances like mucin. Lactobacillus acidophilus produces lactase (β-galactosidase), which helps break down lactose into simpler sugars, easing symptoms like bloating and cramps in lactose-intolerant people. It also supports heart health by reducing cholesterol absorption in the gut and helping remove cholesterol from arteries, lowering the risk of plaque build-up. For immunity, it boosts protective antibodies (like IgG and IgA), increases helpful immune cells (CD4⁺), and reduces inflammation by lowering inflammatory markers like IL-6 and TNF-α. In oral health, it competes with harmful bacteria, reducing plaque and the risk of cavities. In pregnant women with gestational diabetes, taking L. acidophilus through probiotic yogurt lowered blood sugar and HbA1c levels, likely by producing beneficial acids that improve insulin sensitivity and reduce inflammation. It also helps in managing skin issues like eczema in children with allergies by lowering inflammation and reducing allergy-related markers when taken daily.

Gut barrier integrity- The strength and health of the intestinal lining, which acts as a protective shield to let nutrients into the body while keeping harmful bacteria and toxins from leaking out.

Tight junction proteins- Specialized molecular "stitches" that lock the cells of our gut lining tightly together, preventing unwanted substances from slipping between them into the bloodstream.

Mucin- A thick, slippery protein that forms the core of mucus, coating and protecting delicate internal tissues like the stomach and intestines from irritation and germs.

Lactose-intolerant- The inability to fully break down and digest lactose, the natural sugar found in dairy products, often leading to gas, bloating, or stomach cramps.

Antibodies- Custom-made protective proteins created by the immune system to recognize, latch onto, and neutralize specific invading germs.

Inflammatory markers- Measurable chemicals or proteins in the body that spike when the immune system is actively fighting off an infection, injury, or irritation.

Plaque- A sticky, stubborn buildup; this most commonly refers to the film of bacteria that forms on teeth or the fatty deposits that accumulate inside arteries.

HbA1c levels- A standard blood test measurement that reveals a person's average blood sugar levels over the past two to three months, crucial for tracking diabetes risk.

Applications of Lactobacillus acidophilus

Lactobacillus acidophilus is broadly utilised in the fermentation of dairy, meat, and plant-based products, where it enhances their nutritional value, sensory attributes, and shelf life. Fermentation by Lactobacillus acidophilus boosts nutritional and antioxidant properties in fruit and vegetable juices. Lactobacillus acidophilus produces organic acids, which results in increasing acidity and prevents spoilage by hindering the growth of bad microbes, thus extending the shelf life of the product. Acidophilus milk, a fermented drink enriched with Lactobacillus acidophilus, aids in better digestion and controls cholesterol levels.

Fermentation- A natural process where microbes (like bacteria or yeast) break down sugars and carbs without oxygen, turning them into beneficial acids, gases, or alcohol (as seen in yogurt, kimchi, and sourdough).

Sensory attributes- The physical characteristics of a food or product that you experience directly through your senses, including its taste, smell, texture, and color.

Antioxidant- A helpful compound that shields human cells from damage caused by harmful, unstable molecules called free radicals, effectively lowering cellular stress.

Microbe profile

Shape: Rod-shaped

Gram nature: Gram-positive

Spore formation: No

Oxygen requirement: Microaerobic- requires oxygen for survival but cannot tolerate normal atmospheric oxygen concentrations.

Optimal temperature: 35–38°C

Optimal pH: 5.5–6.0

Food source: Glucose, fructose, lactose, and sucrose

Taxonomic Classification

Domain: Bacteria

Phylum: Bacillota

Class:Bacilli

Order:Lactobacillales

Family:Lactobacillaceae

Genus:Lactobacillus

Species:Lactobacillus acidophilus

Reference

Bull, M., Plummer, S., Marchesi, J., & Mahenthiralingam, E. (2013). The life history of Lactobacillus acidophilus as a probiotic: a tale of revisionary taxonomy, misidentification and commercial success. FEMS microbiology letters, 349(2), 77–87. https://doi.org/10.1111/1574-6968.12293

Gao, H., Li, X., Chen, X., Hai, D., Wei, C., Zhang, L., & Li, P. (2022). The Functional Roles of Lactobacillus acidophilus in Different Physiological and Pathological Processes. Journal of microbiology and biotechnology, 32(10), 1226–1233. https://doi.org/10.4014/jmb.2205.05041

Liu, Y., Nawazish, H., Farid, M. S., Abdul Qadoos, K., Habiba, U. E., Muzamil, M., Tanveer, M., Sienkiewicz, M., Lichota, A., & Łopusiewicz, Ł. (2024). Health-Promoting Effects of Lactobacillus acidophilus and Its Technological Applications in Fermented Food Products and Beverages. Fermentation, 10(8), 380. https://doi.org/10.3390/fermentation10080380

Huang, Y., Wang, J., Quan, G., Wang, X., Yang, L., & Zhong, L. (2014). Lactobacillus acidophilus ATCC 4356 prevents atherosclerosis via inhibition of intestinal cholesterol absorption in apolipoprotein E-knockout mice. Applied and environmental microbiology, 80(24), 7496–7504. https://doi.org/10.1128/AEM.02926-1

Gao, H., Li, X., Chen, X., Hai, D., Wei, C., Zhang, L., & Li, P. (2022). The Functional Roles of Lactobacillus acidophilus in Different Physiological and Pathological Processes. Journal of microbiology and biotechnology, 32(10), 1226–1233. https://doi.org/10.4014/jmb.2205.05041

Tahmourespour, A., & Kermanshahi, R. K. (2011). The effect of a probiotic strain (Lactobacillus acidophilus) on the plaque formation of oral Streptococci. Bosnian journal of basic medical sciences, 11(1), 37–40. https://doi.org/10.17305/bjbms.2011.2621

Sahhaf Ebrahimi, F., Homayouni Rad, A., Mosen, M., Abbasalizadeh, F., Tabrizi, A., & Khalili, L. (2019). Effect of L. acidophilus and B.lactis on blood glucose in women with gestational diabetes mellitus: a randomized placebo-controlled trial. Diabetology & metabolic syndrome, 11, 75. https://doi.org/10.1186/s13098-019-0471-5

Nakata, J., Hirota, T., Umemura, H., Nakagawa, T., Kando, N., Futamura, M., Nakamura, Y., & Ito, K. (2019). Additive effect of Lactobacillus acidophilus L-92 on children with atopic dermatitis concomitant with food allergy. Asia Pacific allergy, 9(2), e18. https://doi.org/10.5415/apallergy.2019.9.e18

PROBIOTICS

LACTOSE INTOLERANCE

LACTOBACILLUS ACIDOPHILUS

Frequently Asked Questions

From what source was Lactobacillus acidophilus first isolated in 1900?

It was originally isolated from infant feces by a researcher named Moro.

How does L. acidophilus help people who are lactose-intolerant?

It produces lactase, an enzyme that breaks down milk sugar to ease symptoms like bloating and cramps.

How does this bacterium help protect against arterial plaque build-up?

It reduces cholesterol absorption in the gut and assists in clearing cholesterol directly from the arteries.

What clinical benefit does L. acidophilus offer to pregnant women with gestational diabetes?

Consuming it via probiotic yogurt helps successfully lower blood sugar and long-term HbA1c levels.

What does a "microaerobic" oxygen requirement mean for this microbe?

It means the bacterium needs oxygen to survive but cannot tolerate normal, full atmospheric concentrations.

BugSpeaks®

BugSpeaks®, developed by Leucine Rich Bio Pvt Ltd, South Asia’s first microbiome company, is headquartered in Bengaluru, India. Since 2014, the company has pioneered advanced analytics to analyze complex genomics data. Collaborating with leading research institutes globally, Leucine Rich Bio has leveraged its expertise to create BugSpeaks®, South Asia’s first gut microbiome test.

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