''Lacticaseibacillus casei'' is an organism that belongs to the largest genus in the family ''

Lactobacillaceae The ''Lactobacillaceae'' are a family of lactic acid bacteria. It is the only family in the lactic acid bacteria which includes homofermentative and heterofermentative organisms; in the ''Lactobacillaceae,'' the pathway used for hexose fermentati ...

'', a

lactic acid bacteria Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bact ...

(LAB), that was previously classified as ''Lactobacillus casei''. This bacteria has been identified as

facultatively anaerobic A facultative anaerobic organism is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent. Some examples of facultatively anaerobic bacteria are ''Staphylococcus' ...

or microaerophilic, acid-tolerant, non-spore-forming bacteria. This species is a non-sporing, rod-shaped, gram positive microorganism that can be found within the reproductive and digestive tract of the human body. Since ''L. casei'' can survive in a variety of environmental habitats, it has and continues to be extensively studied by health scientists. Commercially, ''L. casei'' is used in fermenting dairy products and its application as a

probiotic Probiotics are live microorganisms that provide health benefits when consumed, generally by improving or restoring the microbiota in the gut. Probiotics are considered generally safe to consume, but may cause bacteria– host interactions ...

In bacteraemia, it is regarded to be similar in pathogenicity to Lactobacillus and associated with

infective endocarditis Infective endocarditis is an infection of the inner surface of the heart (endocardium), usually the heart valve, valves. Signs and symptoms may include fever, petechia, small areas of bleeding into the skin, heart murmur, feeling tired, and anem ...

Taxonomy

The taxonomy of the ''L. casei'' group has been debated for several years because researchers struggled to differentiate between the strains of ''L. casei'' and '' L. paracasei'' using methods of traditional bacteriology, i.e. phenotypic, physiological, and biochemical similarities. In the 1990s, researchers began to realize that the

type strain The International Code of Nomenclature of Prokaryotes (ICNP) or Prokaryotic Code, formerly the International Code of Nomenclature of Bacteria (ICNB) or Bacteriological Code (BC), governs the scientific names for Bacteria and Archaea.P. H. A. Sneath ...

for ''L. casei'', ATCC 393, does not quite match most other strains classified as "L. casei" by then. To solve this discrepancy, Dellaglio ''et al.'' argued to simply replace the type with ATCC 334, which is closer to these "other strains", and to bury the name "L. paracasei". This argument was not accepted by the ICSP, which ruled in 1994 and 2008 that the type strain should not be changed. ICSP also mentions that ATCC 334 is a strain of ''L. paracasei'', meaning that it's the aforementioned "other strains" that need to be moved to ''paracasei''. The next major event in taxonomic revision came with Zheng ''et al.'' 2020, which split ''

Lactobacillus ''Lactobacillus'' is a genus of gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically div ...

'' into several genera on phylogenomic grounds. ''L. casei'' was made the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of '' Lacticaseibacillus'', containing more than 20 species. As of December 2023, the accepted taxonomy under the

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

is as follows: * ''Lacticaseibacillus casei'' ** ''Lactobacillus casei'' subsp. ''pseudoplantarum'' was not adjusted by Zheng, but remains valid. It is, however, phylogenomically problematic: the type strain is classified by ATCC, JCM, and BCCM as ''L. paracasei'' subsp. ''paracasei''. * '' Lacticaseibacillus chiayiensis'' * '' Lacticaseibacillus paracasei'' ** ''Lacticaseibacillus paracasei'' subsp. ''paracasei'' ** ''Lacticaseibacillus paracasei'' subsp. ''tolerans'' * '' Lacticaseibacillus rhamnosus'' * '' Lactobacillus zeae''

Uses

Dairy

The most common application of ''L. casei'' is industrial, specifically for

dairy A dairy is a place where milk is stored and where butter, cheese, and other dairy products are made, or a place where those products are sold. It may be a room, a building, or a larger establishment. In the United States, the word may also des ...

production. ''Lacticaseibacillus casei'' is typically the dominant species of nonstarter lactic acid bacteria (i.e. contaminant bacteria) present in ripening

cheddar cheese Cheddar cheese (or simply cheddar) is a natural cheese that is relatively hard, off-white (or orange if colourings such as annatto are added), and sometimes sharp-tasting. It originates from the English village of Cheddar, Somerset, Cheddar in ...

, and, recently, the complete genome sequence of ''L. casei'' ATCC 334 has become available. ''L. casei'' is also the dominant species in naturally fermented Sicilian green olives.

Medical

A commercial beverage containing ''L. casei'' strain Shirota has been shown to inhibit the ''

in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, an ...

'' growth of ''

Helicobacter pylori ''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, Flagellum#bacterial, flagellated, Bacterial cellular morphologies#Helical, helical bacterium. Mutants can have a rod or curved rod shape that exhibits l ...

'', but when the same beverage was consumed by humans in a small trial, ''H. pylori'' colonization decreased only slightly, and the trend was not statistically significant. Some ''L. casei'' strains are considered to be

, and may be effective in alleviation of gastrointestinal pathogenic bacterial diseases. According to

World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...

, those properties have to be demonstrated on each specific strain—including human clinical studies—to be valid. ''L. casei'' has been combined with other probiotic strains of bacteria in randomized trials studying its effects in preventing antibiotic-associated diarrhea (AAD) and ''

Clostridioides difficile ''Clostridioides difficile'' ( syn. ''Clostridium difficile'') is a bacterium known for causing serious diarrheal infections, and may also cause colon cancer. It is known also as ''C. difficile'', or ''C. diff'' (), and is a Gram-positive spec ...

'' infections (CDI), and patients in the trials who were not given the placebo had significantly lower rates of AAD or CDI (depending on the trial) with no adverse effects reported. Additionally, trials have shown significantly shorter recovery times in children suffering from acute diarrhea (primarily caused by rotavirus) when given different ''L. casei'' treatments when compared to placebo. Studies suggest that lactobacilli are a safe and effective treatment for acute and infectious diarrhea. In the preparation of food, ''L. casei'' bacteria can be used in the natural

fermentation Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduce ...

of beans to lower levels of the compounds causing flatulence upon digestion. Another strain that has been studied is "01", also known as "Lc-01" or ''Lacticaseibacillus casei''-01.

Commercial probiotic

Among the best-documented probiotic strains of ''L. casei'', ''L. casei'' DN-114001 ( Actimel/DanActive) and ''L. casei'' Shirota ( Yakult) have been extensively studied and are widely available as

functional food A functional food is a food claimed to have an additional benefit beyond just nutrition (often one related to health promotion or disease prevention) by modifying the horticulture, cultivation of the native food or by food additive, adding ingr ...

s. The genomes of these two strains have been sequenced from commercial yogurt, re-designated "LcA" and "LcY" respectively. They were found to be extremely closely related.

Others

In the past few years, many studies have been conducted in the decolorization of

azo dyes Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C−N=N−C li ...

by lactic acid bacteria such as ''L. casei'' TISTR 1500, ''L. paracasei'', ''Oenococcus oeni'', etc. With the azoreductase activity, mono- and diazo bonds are degraded completely, and generate other aromatic compounds as intermediates.

Characteristics of ''Lactocaseibacillus casei''

The following table includes the colony, morphological, physiological, and biochemical characteristics of ''L. casei''.

Transformation

Lactic acid bacteria (LAB) is widely exploited for its probiotic and fermenting properties, so understanding how its genetic material is exchanged was crucial for researchers. A wide variety of comparative analyses were used to determine that

horizontal gene transfer Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). HGT is an important factor in the e ...

(HGT) influenced the evolution of the ''Lactobacillus'' genus. HGT in ''L. casei'' includes

transformation Transformation may refer to: Science and mathematics In biology and medicine * Metamorphosis, the biological process of changing physical form after birth or hatching * Malignant transformation, the process of cells becoming cancerous * Trans ...

conjugation Conjugation or conjugate may refer to: Linguistics *Grammatical conjugation, the modification of a verb from its basic form *Emotive conjugation or Russell's conjugation, the use of loaded language Mathematics *Complex conjugation, the change o ...

, and transduction. The mobile genetic elements found within the genome, known as

mobilome The mobilome is the entire set of mobile genetic elements in a genome. Mobilomes are found in eukaryotes, prokaryotes, and viruses. The compositions of mobilomes differ among lineages of life, with transposable elements being the major mobile ele ...

s, play an important role in ''Lactobacillaceae'' transfer. This includes insertion sequences,

bacteriophage A bacteriophage (), also known informally as a phage (), is a virus that infects and replicates within bacteria. The term is derived . Bacteriophages are composed of proteins that Capsid, encapsulate a DNA or RNA genome, and may have structu ...

integron Integrons are genetic mechanisms that allow bacteria to adapt and evolve rapidly through the stockpiling and expression of new genes. These genes are embedded in a specific genetic structure called gene cassette (a term that is lately changing to i ...

plasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria and ...

s, genomic islands, and

transposons A transposable element (TE), also transposon, or jumping gene, is a type of mobile genetic element, a nucleic acid sequence in DNA that can change its position within a genome. The discovery of mobile genetic elements earned Barbara McClinto ...

. Within LAB, they are responsible for metabolizing different molecules, hydrolyzing proteins, resisting antibiotics, DNA, and phages, and modifying genetic elements. The first form of gene transfer used by ''Lactobacillus'' is transformation. This includes the uptake of naked DNA by a recipient bacterial cell to gain the genetic information of a donor cell. This occurs after a donor bacterium has undergone autolysis and its DNA fragments are left within the free extracellular fluid. The recipient bacterium will then ingest the DNA fragments and will result in either a bacterial cell with a plasmid or recombination of the recipient DNA will transpire within the chromosome. The next form of transfer is conjugation, a process that involves the transfer of DNA from a ''Lactobacillus'' donor to a recipient via cell-to-cell contact or direct cytoplasmic contact. In this process, the recipient cell is known as the transconjugant. Once the cells come together, fragments of DNA are directly transferred from the donor to the transconjugant. This is mediated by pheromone-induced cell aggregation and mobilization proteins since many of the plasmids are unable to transfer on their own. Afterward, the mating cells will separate and a recombinant cell will be produced after homologous recombination. Finally, transduction in ''Lactobacillus'' cells is a bacteriophage-mediated transfer of plasmid or chromosomal genetic information. To initiate this process, a bacteriophage must first infect the donor cell so that

lysis Lysis ( ; from Greek 'loosening') is the breaking down of the membrane of a cell, often by viral, enzymic, or osmotic (that is, "lytic" ) mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a ...

of the cell will occur. At this point, the cell lysate will be filled with phages that carry donated genome fragments and the recipient cell will be injected with abnormal phage. This will result in a recombination cell whether the cell is infected after homologous recombination or after the infection occurs by bacteriophage integrase.

References

External links

Type strain of ''Lactobacillus casei'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Authority control Bacteriology Digestive system Probiotics Gut flora bacteria Dairy farming Lactobacillaceae Alternative medicine Bacteria used in dairy products Bacteria described in 1916 Gram-positive bacteria