paracasei) is a gram-positive, homofermentative species of lactic acid bacteria that are commonly used in dairy product fermentation and as probiotic cultures.

[2][3] A protracted refrigeration period before in vitro gastrointestinal transit (GIT) did not affect or influenced very weakly cell resistance.

[5][3][7] Its fermentative properties allows it to be used as biological food processors and supplements for diets and medical disorders, especially in the gastrointestinal tract.

paracasei is part of the phylum Bacillota, the class Bacilli,[6] the order Lactobacillales and the family Lactobacillaceae respectively.

[2] L. paracasei has been found to show specific differences with other lactobacilli in that it is somewhat heat resistant, grows well in ripening cheese, and it has high proteolytic activity.

[16] Lacticaseibacillus paracasei's genome contains circular DNA and varies slightly among the different strains isolated.

[3] The difference in the genomes of these strains lies in variant cell envelopes, secretory proteins, and polysaccharides.

[2] Genetic diversity for the different L. paracasei genomes was assessed using multilocus sequence typing (MLST) and amplified fragment length polymorphism (AFLP).

[23] 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.

[24] Oral administration of heat-killed Lactobacillus paracasei MoLac-1 increased the proportion of NK cells in spleen, and ameliorated the symptoms of influenza virus(IFV) infection in mice.

[25] 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.

[31] The Lactobacillus paracasei may reduce GI symptom severity and improve the psychological well-being of individuals with certain IBS subtypes.

Strain 8700:2 breaks down oligofructose and inulin, while also growing rapidly on both and producing lactic acid as the end product.

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.

[9] Some people, such as those with immune compromise, short bowel syndrome, central venous catheters, cardiac valve disease and premature infants, may be at higher risk for adverse events.

In 1991, Martinus Beijerinck, a Dutch microbiologist, separated Lactobacillus as gram positive bacteria from the previously known LAB group.

paracasei was proposed for rejection in 1996 by Dicks, Duplessis, Dellaglio, and Lauer[6] but subsequent work confirmed the validity of the species.