Lacticaseibacillus paracasei

Lacticaseibacillus paracasei is a gram-positive, facultatively heterofermentative, non-spore forming microorganism. The cells of Lc. paracasei are typically rod shaped, with a size range of 2.0μm to 4.0μm in width, and 0.8 to 1.0μm in length. The organism is nonmotile. Lc. paracasei cells often have square ends, and may exist either in single form or in chains. No growth takes place above 40 °C. The organism is able to survive for approximately 40 seconds in a maximum temperature of 72 °C. Freezing at -20 degrees C and -70 degrees C had much less adverse effect on viability than did storage at 7 degrees C Lacticaseibacillus paracasei temporarily exists as a common inhabitant of the human gastrointestinal tract as part of the normal microbiota. Naturally fermented vegetables, milk, and meat may also contain strains of L. paracasei. == Phylogeny ==

Lacticaseibacillus paracasei belongs to kingdom Bacteria. Lc. paracasei is part of the phylum Bacillota, the class Bacilli, == Genomics ==

''Lacticaseibacillus paracasei's'' genome contains circular DNA and varies slightly among the different strains isolated. On average, the genomes are 2.9 to 3.0 million base pairs (commonly abbreviated Mb). It has a GC-content between 46.2 and 46.6% and is predicted to encode about 2800 to 3100 proteins. AFLP is a Polymerase Chain Reaction (PCR) tool used in DNA profiling to amplify a desired DNA fragment with the use of restriction enzymes and ligands. == Clinical and research applications==

Lacticaseibacillus paracasei has been identified as a bacterium that has probiotic properties. Allergic respiratory disease A systematic review provided significant evidence of beneficial clinical and immunologic effects of Lc. paracasei LP-33 strains in the treatment of Allergic rhinitis. Ingestion of LP-33(Lactobacillus paracasei 33 )-fortified fermented milk for 30 days can effectively and safely improve the quality of life of patients with allergic rhinitis, and may serve as an alternative treatment for allergic rhinitis. Lacticaseibacillus paracasei BRAP01 are the dominant strains inducing IFN-γ/IL-10 production in Taiwanese individuals. For allergic rhinitis (AR), oral administration of Lactobacillus paracasei (all stored at 4°C before consumption) with more than 10 billion bacteria (1x1010CFU) per day for 8 weeks can improve nasal itching (AR's key clinical features) and reduced secretion of the pro-inflammatory mediator IL-5. Atopic dermatitis, Urticaria Oral administration of L. paracasei KBL382 significantly reduced atopic dermatitis(AD)-associated skin lesions, epidermal thickening, serum levels of immunoglobulin E, and immune cell infiltration. Common cold L. paracasei MCC1849 has the potential to improve resistance to common cold infections in susceptible subjects and maintain a desirable mood state, even under mental stress conditions. Coronavirus disease (COVID-19) The Lacticaseibacillus paracasei DG strain significantly induced the expression of genes involved in protective antiviral immunity and prevented the expression of proinflammatory genes triggered by SARS-CoV-2 infection. Inflammatory bowel disease A formulation of live bacteria including Lc. paracasei may be used in combination with conventional therapies to treat ulcerative colitis. Lipoteichoic acid from the cell wall of a heat killed Lacticaseibacillus paracasei D3-5 ameliorates aging-related leaky gut, inflammation and improves physical and cognitive functions in mice Diarrhea Lactobacillus paracasei has been shown to inhibit the bacterial activity of Escherichia coli, a common strain of diarrhea-causing bacteria, so Lactobacillus paracasei is used in the treatment of diarrhea. 。 Helicobacter pylori Infection Lacticaseibacillus paracasei showed bacteriostatic and bactericidal activity vs. H. pylori. Irritable bowel syndrome The Lactobacillus paracasei may reduce GI symptom severity and improve the psychological well-being of individuals with certain IBS subtypes. Cancer L. paracasei IMPC2.1 may be a chemoprophylactic in gastrointestinal cells. Gastrointestinal cells are susceptible to apoptosis and cell growth from both heat-killed and viable IMPC2.1 strains. == Health concerns ==

The manipulation of the gut microbiota is complex and may cause bacteria-host interactions. Although probiotics are considered safe, when they are used by oral administration there is a risk of passage of viable bacteria from the gastrointestinal tract to the internal organs (bacterial translocation) and subsequent bacteremia, which can cause adverse health consequences. Currently, the probiotic strain, frequency, dose and duration of the probiotic therapy are not established. == History ==

LAB (Lactic Acid Bacteria) were classified and grouped in the early 1900s after gaining scientists' attention after observing the bacteria's interactions in different foods, especially dairy products. In 1991, Martinus Beijerinck, a Dutch microbiologist, separated Lactobacillus as gram positive bacteria from the previously known LAB group. L. paracasei has been recently classified as a part of the Lacticaseibacillus casei group of probiotics. The name Lc. paracasei was proposed for rejection in 1996 by Dicks, Duplessis, Dellaglio, and Lauer but subsequent work confirmed the validity of the species. == References ==