[Skip to Content](https://www.sigmaaldrich.com#main-content) [](https://www.sigmaaldrich.com/US/en) Products Cart0 USEN Products [Login / Register](https://www.sigmaaldrich.com/oidc-sign-in) [Order Lookup](https://www.sigmaaldrich.com/US/en/order-lookup) [Quick Order](https://www.sigmaaldrich.com/US/en/quick-order) Cart0 [Home](https://www.sigmaaldrich.com/US/en)[Bacteriology](https://www.sigmaaldrich.com/US/en/applications/clinical-testing-and-diagnostics-manufacturing/bacteriology)*Lactobacilli* Basics, Testing & Identification # *Lactobacilli* Basics, Testing & Identification __Jvo Siegrist__ *Microbiology Focus Edition 1.1* ## Structure and Metabolism of *Lactobacillus* *Lactobacilli* \[sing: lactobacillus] are rod-shaped, gram-positive, fermentative, facultative anaerobic, or microaerophilic organotrophs that play an important and varied role in human health. Normally, they form straight rods but under certain conditions spiral or coccobacillary forms have been observed. In most cases, they form chains of varying lengths. *Lactobacilli* belong to the lactic acid bacteria and comprise a major part of this group. As their name implies, they produce lactic acid and derive energy from the fermentation of lactose, glucose, and other sugars to lactate *via* homofermentative metabolism.  Rod-shaped *Lactobacillus bacteria* About 85-90% of the sugar utilized in the fermentative process is converted to lactic acid. Also, some heterofermentative *lactobacilli* produce alcohol in addition to lactic acid from sugars. This acid-producing mechanism inhibits the growth of other organisms and favors the growth of *lactobacilli* that thrive in low-pH environments. ATP is generated during the process by non-oxidative substrate-level phosphorylation. ### Read more about - [](https://www.sigmaaldrich.com)[*Lactobacillus* Species Groups](https://www.sigmaaldrich.com#lactobacillus) - [Natural Source](https://www.sigmaaldrich.com#natural) - [Advantage of *Lactobacilli*](https://www.sigmaaldrich.com#advantage) - [Identification of *Lactobacilli* and Bifidobacteria](https://www.sigmaaldrich.com#identification) - [Watch HybriScan Rapid Microbial System Video](https://www.sigmaaldrich.com#hybriscan-video) - [Product Listings](https://www.sigmaaldrich.com#product-listings) [Request More Information](https://www.sigmaaldrich.com/US/en/campaigns/microbial-culture-media-more-info) * * * ### *[](https://www.sigmaaldrich.com)Lactobacillus* are divided into three groups based on their metabolism (According to Kandler and Weiss): - Obligately homofermentative (Group I) *L. acidophilus,* L. delbrueckii, *L. salivarius, L. helveticus* - Facultatively heterofermentative (Group II) *L. casei, L. plantarum, L. curvatus, L. sakei* - Obligately heterofermentative (Group III) *L. brevis, L. buchneri, L. fermentum*, *L. reuteri* *Lactobacilli* have a generation time ranging from 25 to several hundred minutes. The optimal growth temperature ranges from 30 to 40 °C, although some thermophilic strains grow well and have highly activated metabolism at temperatures around 45 °C. ## [](https://www.sigmaaldrich.com)NATURAL SOURCE *Lactobacilli* are ubiquitous and normally harmless. In humans and animals, they are found in the intestinal tract and perform many beneficial functions, including immunomodulation, suppression of enteric pathogens, and maintenance of intestinal flora. On the contrary, *Lactobacilli* decompose plant material and are responsible for spoiling vegetables, fruits, beverages, and other nutrients. *L. casei* and *L. brevis* are two of the most common beer-spoilage organisms. Certain *lactobacilli* like *L.* *delbrueckii* are known to cause urinary tract infections.1 [Download the brochure to learn about the portfolio of products and workflow for spoilage testing in beverages](https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/378/001/beverage-safety-testing-br5194en-ms.pdf). ## [](https://www.sigmaaldrich.com)ADVANTAGES OF *LACTOBACILLI* Life without *Lactobacilli* is unimaginable: They are used in the production of yogurt, cheese, chocolate, sourdough bread, sauerkraut, pickles, kimchi (a traditional Korean pickled dish), beer, wine, cider, and many other fermented foods. *Lactobacilli* are also important in animal feed (silage) production. They produce lactic acid, lower the pH and thereby inhibit the growth of bacteria. Many studies have shown the beneficial effect of a healthy intestinal *Lactobacilli*-containing microflora. Their potential therapeutic roles include anti-inflammatory, anti-cancer, and boosting the immune system, among other benefits. As a result, *Lactobacilli* are often added to foods as a probiotic supplement. ## [](https://www.sigmaaldrich.com)IDENTIFICATION OF *LACTOBACILLI* AND BIFIDOBACTERIA Selective media is widely used to differentiate *lactobacilli* based on their phenotype. Classical phenotypic tests for the identification of *lactobacilli* are based on physiological characteristics, like motility, growth temperature, respiratory type, and growth in sodium chloride, as well as on diverse biochemical characteristics, such as fermentation type, metabolism of carbohydrate substrates, production of lactic acid isomers, coagulation of milk and presence of specific enzymes like arginine dihydrolase. In Bergey’s Manual, *Lactobacillus* is described as a Gram-positive rod, non-spore forming, acid-fast negative, and catalase negative. The colony morphology on certain media is taken for presumptive identification. There are also three API tests (API 50 CH, LRA Zym, and API Zym) for identification, but the reliability of these tests has been questioned 2. Another interesting method is the protein fingerprint, where an SDS gel electrophoresis is made of the whole bacteria cell. [](https://www.sigmaaldrich.com)As a modern alternative, molecular biology-based methods, like PCR, can be consulted. However, they are often quite expensive. We provide a revolutionary molecular biology method – [HybriScan® Rapid Microbial Test System](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/microbiological-testing/pathogen-and-spoilage-testing/hybriscan-rapid-test) that is rapid, easy, and cost-effective. Based on the detection of rRNA, this method completely avoids the need for PCR amplification. The sandwich hybridization test, called HybriScan®, is performed on a microtiter plate. The range of *Lactobacilli* detected by HybriScan® tests is listed in Table below. [Learn More](https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/microbiological-testing/pathogen-and-spoilage-testing/new-fast-and-innovative) * * * ## Product Listings Sorry, an unexpected error has occurred Response not successful: Received status code 500 * * * ### References 1\. Darbro BW, Petroelje BK, Doern GV. 2009. Lactobacillus delbrueckii as the Cause of Urinary Tract Infection. Journal of Clinical Microbiology. 47(1):275-277. [https://doi.org/10.1128/jcm.01630-08](https://doi.org/10.1128/jcm.01630-08) 2\. Coeuret V, Dubernet S, Bernardeau M, Gueguen M, Vernoux JP. 2003. Article. Lait. 83(4):269-306. 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