Lactobacillus jensenii

Template:Biorealm genus

Lactobacillus jensenii. From Osel: The Bacterio-Therapeutics Company.

Classification

Higher order taxa

Bacteria; Firmicutes; Bacilli; Lactobacillales; Lactobacillaceae; Lactobacillus

Genus

Lactobacillus jensenii

NCBI: Taxonomy

Description and significance

From the genus Lactobacillus, L. jensenii is a "facultatively anaerobic, catalase-negative, none-spore-forming, Gram Positive, rod-shaped" bacteria. This particular strain is one of the predominant species (along with Lactobacillus crispatus) found in the female lower genital tract. Because this bacteria is a natural vaginal strain, this novel microorganism has become a special interest to HIV/AIDS researchers who are looking for a genetically modifiable container that would express HIV inhibitors (CV-N). So, to facilitate efficient expression of CV-N by this bacterium, L. jensenii 1153 genome was first sequenced by shotgun approach.

Lactobacillus jensenii. From [1]

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

To ensure efficiency of heterologous expression and control the basis of genetic engineering of vaginal lactobacilli, L. jensenii 1153 genome has been sequenced. Analysis shows that its genome contains over 1600 ORFs which include "novel cell wall anchor domains, unique signal sequences, powerful promoter elements, and possible sites for chromosomal integration of heterologous genes." Its DNA has low G+C content and produces D-lactic acid as its major product.

Cell structure and metabolism

L. jensenii, like other members of the Lactobacillus, are rod-shaped, anaerobic gram positive microorganisms. It can be differentiated from other species because of the following characteristics: hydrolysis of arginine, production of D-lactate (only), and fermentation of galatose, ribose, and cellobiose, but not of lactose.

As an anaerobe, L. jensenii is responsible for producing acid in the vagina by anaerobic metabolism of glycogen. The glycogen are deposited in the vaginal epithelium when there is a high level of estrogen, specifically during menstruation period. The vaginal flora and the surrounding epithelial cells metabolize the glycogen into acetic and lactic acid so that the vaginal pH becomes about 4. The strong concentration of the acidic environment help protect the vagina from harmful pathogens in the environment.

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Lactobacillus jensenii (along with Lactobacillus crispatus and Lactobacillus gasseri) is a natural vaginal strain of bacteria colonized in the "biofilms" of the vaginal mucosa of healthy females. Because of its capability to produce H2O2, it is able to reduce the transmission and infections of genital related diseases such as gonorrhea, urinary tract infection, and chlamydia or sexual transmitted disease such as HIV.

Human Lactobacillus strain has difficulty when replicating outside the body.

So far, its pathogenicity for men is unknown.

Application to Biotechnology

Fermented Yoghurt containing antioxdiant activity of L. paracasei subsp. paracasei SM20 and P. jensenii SM11 . Swiss National Science Foundation and a Swiss dairy company. From [2]

Research by Beckman and Ames 1998 demonstrate that free radicals and reactive oxygen species (ROS) helps prevent atherosclerosis, diabetes, and cancer. These radicals that form from aerobic respiration while food digestion can damage cells. Food containing antioxidants are able to help quicken the restoration of damaged tissues/cells, therefore, increasing the defense mechanism of the body. Because anaerobic bacteria such as L. jengenii possess anti-oxidant activity, their ability to break down superoxide anion and H2O2 with milk proteins is the highlight of current studies. Researches are concluding "Lactobacillus jensenii strain showed high antioxidant potential...and it had also high content of hydrophobic amino acids, valine, leucine, phenylalanine and tryptophan." The strain's specific amino acid content matters because its hydrophobic properties of its composition are related to the inhibition of peroxidation activities. Because of this property, we may be able to create fermentated milk that can now possess higher antioxidant activity.

Current Research

Some of the recent researches on Lactobacillus jensenii:

"Inhibition of HIV infectivity by a natural human isolate of Lactobacillus jensenii engineered to express functional two-domain CD4"

Knowing that HIV enters through cervico-vaginal mucosa, Lactobacillus jensenii, which is known to naturally colonize in the vaginal area, is genetically engineered to secrete two-domain CD4 (2D CD4) proteins. The secreted 2D CD4 binds to anti-CD4 receptor and bound HIV-1 gp120, which shows that the engineering did not affect the L. jensenii proteins structure. Moreover, with the usage of luciferase reproter gene, single-cycle infection assays confirmed that the modified L. jensenii is able to inhibit HIV-1 from infecting target cells. Furthermore, when the bacteria was incubated with recombinant HIV-1HxB2 reporter virus, the infectivity of HeLa cells expressing CD4–CXCR4–CCR5 decreased considerably. The decrease in infectivity of HIV-1 with dosage controlled engineered L. jensenii may be a convenient contraception by using natural occuring colonies of bacteria inside the body to block the transmission of HIV.

Engineered Vaginal Lactobacillus Strain for Mucosal Delivery of the Human Immunodeficiency Virus Inhibitor Cyanovirin-N

Lactobacillus jensenii has been genetically engineered to produce and secrete peptide that prevents fusion with HIV using S-protein layer secretion pathway. The modification did not affect the phenotype of the bacteria, but rather was integrated stably into the chromosome. This new Lactobacillus CV-N hybrid was capable of inhibiting "CCR5-tropic HIVBaL infectivity in vitro with a 50% inhibitory concentration of 0.3 nM". Genetically engineered L. jensenii was able to proliferate in the vaginas of estrus phase mice as well as secrete this anti-HIV peptide. This may be an inexpensive and convenient way to block HIV infection and/or replication in women.

Inhibition of Neisseria gonorrhoeae by Lactobacillus Species That Are Commonly Isolated from the Female Genital Tract

Four strains (Lactobacillus jensenii, Lactobacillus crispatus, Lactobacillus acidophilus, and Lactobacillus gasseri) of Lactobacillus were studied because of past reports of the possible link between high colonization of Lactobacillus and low risk of gonorrhea. In this experiment, Neisseria species or Escherichia coli strains serving as target organisms and four clinical isolates of N. gonorrhoeae were added at different pH on plates containing heart infusion agar and saline solutions of respective Lactobacillus strains. All four strains were able to inhibit the gonococcal strains at low pH while L. jensenii and L. crispatus was also able to inhibit N. gonnorrhoeae at neutral pH. None of them were able to inhibit E. coli strains, though L. jensenni was able to inhibit Neisseria cinerea. On the quantitative scale of the assay, L. jensenii were particularly most resistant to N. gonorrhoeae in the four strains. The strains were able to use H2O2 as mediator to resist the infection. The paper was able to conclude that the presence of L. jensenii and L. crispatus helps reduce risk of gonorrhoeae.