''Lacticaseibacillus casei ''is an organism that belongs to the largest genus in the family ''
Lactobacillaceae'', 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-01''. This bacteria has been identified as
facultatively anaerobic or microaerophilic, acid-tolerant, non-spore-forming bacteria. The taxonomy of this group has been debated for several years because researchers struggled to differentiate between the strains of ''L. casei'' and ''
L. paracasei
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, th ...
''. It has recently been accepted as a single species with five subspecies:
''L. casei'' subsp. ''rhamnosus'', ''L. casei'' subsp. ''alactosus'', ''L. casei'' subsp. ''casei'', ''L. casei'' subsp. ''tolerans'', and ''L. casei'' subsp. ''pseudoplantarum''.
The taxonomy of this genus was determined according to the phenotypic, physiological, and biochemical similarities.
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.
Uses
Dairy
The most common application of ''L. casei'' is industrial, specifically for
dairy
A dairy is a business enterprise established for the harvesting or processing (or both) of animal milk – mostly from cows or buffaloes, but also from goats, sheep, horses, or camels – for human consumption. A dairy is typically located on ...
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. Cheddar originates from the English village of Cheddar in Somerset.
C ...
, 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
The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' 'M ...
.
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, and ...
'' growth of ''
Helicobacter pylori
''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, microaerophilic, spiral (helical) bacterium usually found in the stomach. Its helical shape (from which the genus name, helicobacter, derives) is th ...
'', 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
probiotic, and may be effective in alleviation of gastrointestinal pathogenic bacterial diseases. According to
World Health Organization
The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...
, 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 ''
Clostridium difficile
''Clostridioides difficile'' (syn. ''Clostridium difficile'') is a bacterium that is well known for causing serious diarrheal infections, and may also cause colon cancer. Also known as ''C. difficile'', or ''C. diff'' (), is 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
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 fermentat ...
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 of beans to lower levels of the compounds causing flatulence upon digestion.
Commercial probiotic
Among the best-documented, probiotic ''L.casei'', ''L. casei'' DN-114001, and ''L. casei'' Shirota have been extensively studied and are widely available as
functional food
A functional food is a food claimed to have an additional (often one related to health promotion or disease prevention) by adding new ingredients or more of existing ingredients. The term may also apply to traits purposely bred into existing ed ...
s (see
Actimel/DanActive,
Yakult
is a Japanese sweetened probiotic milk beverage fermented with the bacteria strain ''Lacticaseibacillus casei'' Shirota. It is sold by Yakult Honsha, based in Tokyo. It is distributed through convenience stores and supermarkets in single-se ...
).
Others
In the past few years, many studies have been conducted in the decolorization of
azo dyes 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 unicellular and/or multicellular organisms other than by the ("vertical") transmission of DNA from parent to offspring ( reproduction). ...
(HGT) influenced the evolution of the ''Lactobacillus'' genus.
HGT in ''L. casei'' includes
transformation,
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 ...
, and
transduction. The mobile genetic elements found within the genome, known as
mobilomes, play an important role in ''Lactobacillaceae'' transfer. This includes
insertion sequences,
bacteriophage
A bacteriophage (), also known informally as a ''phage'' (), is a duplodnaviria virus that infects and replicates within bacteria and archaea. The term was derived from "bacteria" and the Greek φαγεῖν ('), meaning "to devour". Bact ...
s,
integrons,
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; howev ...
s,
genomic islands, and
transposons
A transposable element (TE, transposon, or jumping gene) is a nucleic acid sequence in DNA that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Trans ...
. 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
Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. This takes place through a pilus. It is a parasexual mode of reproduction in bacteri ...
. 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 ( ) 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 ''lysate''. In molecular bio ...
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.
See also
*
Prebiotic (nutrition)
*
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 ...
References
External links
Type strain of ''Lactobacillus casei'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q139777
Bacteriology
Digestive system
Probiotics
Gut flora bacteria
Cattle
Dairy farming
Lactobacillaceae
Alternative medicine
Bacteria used in dairy products
Bacteria described in 1916
Gram-positive bacteria