Lactobacillus fornicalis is a novel species belonging to the genus Lactobacillus, probiotics found in the female genital area. 

Small green rod-shaped structures

Illustration of lactobacillus species

The Lactobacillus genre is considered the probiotic bacteria (good bacteria) found in the gastrointestinal tract of humans and animals. The lactobacillus species are also found in the urinary tract and female genital areas in the human body. The primary function of this genre is to protect the gastrointestinal tract from harmful pathogens, regulate immunomodulation, increase absorption of nutrients in the intestine, and control the microbiome in the body. Moreover, the lactobacillus genre is also utilized in the food and pharmaceutical industries to replenish the lost lactobacillus species. In the female genital area, there is a microbiota containing multiple species belonging to the lactobacillus genre. These species include Lactobacillus gasseri, Lactobacillus jensenii, Lactobacillus crispatus, Lactobacillus raoultii, and Lactobacillus iners. Lactobacillus fornicalis is a new species found in the female vagina that helps control harmful pathogens’ growth. 

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Overview of Lactobacillus fornicalis

Lactobacillus fornicalis is a rod-shaped, non-motile, non-spore-forming gram-positive bacteria that do not have catalase to convert hydrogen peroxide (H2O2) into oxygen and water. These bacteria do not have cytochrome c oxidase enzyme to oxidize the test agent; therefore, they are oxidase-negative. They are facultative anaerobic bacteria that grow well without incubating the culture under microaerophilic conditions. This bacteria was observed to increase within the range of 20 and 40°C. The optimum temperature was found to be in the range of 35 and 37°C. These species are obligately homofermentative as they produce D- lactic acid and L- lactic acid from glucose, with no gas production from gluconate or glucose. 

A person swabbing inside of the transparent container

Experimental analysis of bacterial culture in the laboratory,

To determine the lactobacillus strains, a sample was collected from the posterior fornix secretions of the vagina. The collected swabs were spread in the Petri dish containing MRS agar after incubating for 48 hours at 37°C. The bacterial colonies were observed to be smooth, round, and white with 1mm in diameter, approximately. The GC content was recorded to be 37 mol%. The new species Lactobacillus fornicalis can be differentiated from other lactobacillus species based on the fermentation of a few carbohydrates. These species include; Lactobacillus gallinarum, Lactobacillus gasseri, Lactobacillus johnsonii, Lactobacillus crispatus, Lactobacillus acidophilus, and Lactobacillus jensenii

Frequency of Lactobacillus fornicalis

In healthy females, lactobacillus species dominate the vagina as they play a significant role in protecting the female from urogenital infections. In the vagina, there are good bacteria like Lactobacillus species and harmful pathogens. However, if the good bacteria dominate the vaginal flora, then the harmful pathogens cannot grow. The lactobacillus species produces lactic acid as a byproduct which lowers the pH to acidic conditions making the vaginal environment an unfavorable condition for the pathogens to develop. However, when the population of the lactobacillus species decreases, the pathogens grow, increasing their population, thus disturbing the vaginal microbiota and causing bacterial vaginosis. 

Rugged pink rod-shaped structures

Close-up illustration of lactobacillus bacterial species, 

There has been minimal research conducted to determine the frequency of occurrence of the Lactobacillus fornicalis in the human vagina. A couple of studies followed by the initial experimentation of identifying Lactobacillus fornicalis were unsuccessful in isolating this bacterial species. Initial research was conducted on 18 healthy female patients in South Africa, where the researchers isolated a new lactobacillus species, Lactobacillus fornicalis. However, another study undertaken later among 23 healthy Swedish women did not identify Lactobacillus fornicalis among the vagina flora. In contrast, among the Mexican female population, the studies showed Lactobacillus fornicalis to be one of the notable lactobacillus species found in the vaginal microbiota. We can determine from various research studies that Lactobacillus fornicalis species is not found in the general healthy female population. Instead, this lactobacillus species is identified only in healthy females in some countries. Similarly, the occurrence of different Lactobacillus species varies among other geographical population groups. Therefore, further research is required to determine the frequency of Lactobacillus fornicalis in a healthy female vaginal microbiome.

Asha Rachel Thomas


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