Limosilactobacillus pontis

Limosilactobacillus pontis
Scientific classification
Domain:	Bacteria
Phylum:	Bacillota
Class:	Bacilli
Order:	Lactobacillales
Family:	Lactobacillaceae
Genus:	Limosilactobacillus
Species:	L. pontis
Binomial name
	Limosilactobacillus pontis; (Vogel et al. 1994) Zheng et al. 2020
Type strain
	ATCC 51518; CCUG 33456; CIP 104232; DSM 8475; JCM 11051; LMG 14187; LTH 2587
Synonyms
	Lactobacillus pontisVogel et al. 1994;

Last updated January 06, 2024

Limosilactobacillus pontis is a rod-shaped, Gram-positive facultatively anaerobic bacterium.^[1] Along with other Lactobacillus species, it is capable of converting sugars, such as lactose, into lactic acid.^[1]Limosilactobacillus pontis is classified under the phylum Bacillota, class Bacilli, and is a member of the family Lactobacillaceae and is found to be responsible for the fermentation of sourdough, along with many other Lactobacillus species.^[1] This microorganism produces lactic acid during the process of fermentation, which gives sourdough bread its characteristic sour taste.

History and discovery

In 1994, Limosilactobacillus pontis was discovered during an experiment focusing on the microflora found in sourdough preparations for making sourdough bread.^[1] Scientists isolated Limosilactobacillus pontis as well as many common species such as Limosilactobacillus reuteri , Levilactobacillus brevis , and Fructilactobacillus sanfranciscensis by investigating protein patterns in cells, physiological features, and running 16S rRNA sequences to look at each Lactobacillus species separately.^[1] An isolate from rye sourdough was discovered to be a new species by reason of protein configurations, physiological features, and by GC-content.^[1]

Phylogeny

Limosilactobacillus pontis was classified as a new species based on the 16S rRNA gene sequence.^[1] Strain LTH 2587^T, also known as DSM 8475/ LMG 14187, was the first strain discovered and named.^[1]

Other strain names include the following: ATCC 51518, CCM 4540, CCUG 33456, CIP 104232, JCM 11051, KCTC 5074, NCIMB 13406, and VTT E-052865.^[4]

Use in food production

Limosilactobacillus pontis is used in the starter for making sourdough bread. The starter consists of water, flour, yeast, and the starter culture of bacteria. The bacteria begin fermentation by breaking down the sugars, forming lactic acid in the process.^[5] This process lowers the pH of the solution, producing a "sour" taste in the final product.^[6]Limosilactobacillus pontis breaks down sugars that cannot be metabolized by the yeast in the culture, just as many Lactobacillus species do.^[5] When wheat flour and water are in solution together, the amylase enzymes present breakdown the starch into maltose, and maltase performs a further breakdown into glucose.^[6] The lactic acid producing bacteria are responsible for breaking down sugars and the yeast uses by-products from this process to form carbon dioxide. The carbon dioxide causes leavening in the dough.^[6]

Species of sourdough lactobacilli exhibit unique technological properties related to the flavor, texture, and shelf-life of sourdough bread.^[5]^[7]Limosilactobacillus pontis expresses genes coding for Cystathionine lyase (Cxl), which contributes to the development of flavor in the process of cheese ripening and it is shown to improve the taste and flavor of bread.^[6]^[8]^[9]

Exopolysaccharides (EPS) produced by lactic acid bacteria are used as alternative biothickeners for viscosification, stabilization, emulsification, and gelling in a variety of food products.^[6] EPS are generally classified in two groups: homopolysaccharides (HoPS), commonly known as glucose or fructose polymers, and heteropolysaccharides. Currently only HoPS have been shown to be useful in making bread.^[10] Various sourdough-associated lactic acid bacteria synthesize glucans and fructans by extracellular glucansucrases or fructansucrases, respectively.^[10]L. pontis, L. panis, L. reuteri, Limosilactobacillus frumenti and F. sanfranciscensis have been shown to produce fructans (levan or inulin) and glucans (dextran, reuteran or mutan).^[10]

Genomics

Limosilactobacillus pontis LTH 2585 and LTH 2586 possess a GC content of 53%. Strain LTH 2587 was determined to have a 53.3% GC content.^[1]^[4]

Limosilactobacillus pontis strain LTH 2587 16S rRNA gene sequenced at 1570 base pairs.^[1]^[4]

Limosilactobacillus pontis strain DSM 8475 16S rRNA-23S rRNA small intergenic spacer was also sequenced at 207 base pairs along with the large intergenic spacer, tRNA-Ile, and tRNA-Ala genes at 403 base pairs for the complete sequence.^[1]^[4]

Other genes that have been sequenced include the following:^[11]

Partial pheS gene for phenylalanyl-tRNA synthase alpha subunit for strain LMG 14188 and strain LMG 14187T.^[11]

Partial tuf gene for elongation factor tu, type strain DSM 8474T.^[11]

Partial recA gene for recombinase A, strain LMG 14187T.^[11]

Complete rpoA gene for RNA polymerase alpha subunit, type strain LMG 14187T.^[11]

Physiology

The sourdough lactobacilli including Fructilactobacillus sanfranciscensis , L. pontis,^[1] Limosilactobacillus panis , Lactiplantibacillus paraplantarum , Companilactobacillus mindensis are considered typical to sourdough environments, especially with an extended fermentation period and/or higher temperatures. Limosilactobacillus pontis seems to remain dominant for a long time during continuous propagation of sourdoughs suggesting their essential role for fermentation.^[1] Additionally, they are enriched during continuous dough propagation. Their persistence ascribes to their competitive metabolisms and adaptation to this environment.^[12]

The following are some factors contributing to their dominance/persistence in sourdough fermentation. Firstly, their carbohydrate metabolism is highly adapted to the main energy sources in dough, maltose and fructose. Use of maltose via maltose phosphorylase and the pentose phosphate shunt with fructose as co-substrate results in a higher energy yield than homofermentative maltose degradation.^[13]^[14] Secondly, the temperature and pH for their growth fit the conditions of sourdough fermentation. The persistent coexistence of these microorganisms in the same context may result from their similar growth rates, in turn determined by temperature and pH.^[1] Thirdly, they own some stress response mechanisms to overcome high/low temperatures, high dehydration/osmolarity, acid, oxidation, and starvation.^[15] Finally, they produce antimicrobial compounds, such as organic acids (lactate, acetate, and others), bacteriocins, and reutericyclin to enhance their competitiveness against a wide range of bacteria.^[1] However, the temperature is an important factor strongly impacting the competitiveness of lactobacilli in sourdough fermentation.^[1] For example, at a high temperature of 40 °C, L. frumenti and L. panis are dominating over L. pontis and L. reuteri .

The sourdough lactic acid bacteria's response to high salt concentration is species specific.^[16] In general, obligate heterofermentative lactobacilli are more sensitive to NaCl compared to other lactobacilli. For instance, L. pontis and F. sanfranciscensis are inhibited by 4% NaCl, while L. paraplantarum and Lactobacillus amylovorus can tolerate up to 6% NaCl.^[6]

Metabolism

The most primary metabolic activity of these microorganisms in sourdough is to produce acid and carbon dioxide; gas production is necessary for the dough leavening if yeast is not added.^[6]

Limosilactobacillus pontis is capable of using fructose as a carbon source and convert stoichiometrically convert fructose to lactic acid and ethanol.^[16] However, when maltose is present, they use it chiefly as an electron acceptor, and fructose is reduced to mannitol.^[8]^[9] It can also metabolize ribose, D-raffinose, and gluconate, but cannot use glucose, L-arabinose, D-xylose, galactose, aesculin, lactose or melibiose.^[17] Its main products from fermenting fructose or maltose are lactate, acetate, ethanol, glycerol, and carbon dioxide. Limosilactobacillus pontis cannot use citrate as an electron acceptor in the presence of maltose.^[16] There is also no presence of catalase activity.^[9]

Limosilactobacillus pontis has the ability to catabolize arginine.^[16] Three enzymes are involved in the process; including arginine deaminase (ADI), ornithine carbamoyltransferase (OTC), and carbamate kinase (CK).^[16] A fourth protein located at the cell membrane acts as transporter, allowing the antiporter exchange between arginine and ornithine.^[16]

Probiotics

A probiotic organism such as Limosilactobacillus pontis, and other lactobacilli, help by balancing numbers of normal microflora in the human body.^[17] Probiotics also give some protection against pathogens, lower levels of cholesterol, cause stimulation of the immune response, and in some cases, protect against specific types of cancer.^[17]

There are potential health benefits by using these lactobacilli in commercial food products such as the lactic acid fermented beverage hardaliye, which is made from the natural fermentation of the red grape or grape juice.^[18]

Limosilactobacillus pontis has the ability to induce NOD2 pathway where NOD2 plays a key role in the immune system by recognizing bacterial molecules and stimulating an immune reaction.^[19] NOD2 is a nucleotide-binding oligomerization domain-containing protein, which is also known as caspase recruitment domain. It may commonly be referred to as an Inflammatory bowel disease protein.^[20]^[21]

Related Research Articles

Sourdough or sourdough bread is a bread made by the fermentation of dough using wild lactobacillaceae and yeast. Lactic acid from fermentation imparts a sour taste and improves keeping qualities.

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 diverse species; a taxonomic revision of the genus assigned lactobacilli to 25 genera.

<span class="mw-page-title-main">Rugbrød</span> Danish-style rye bread

Rugbrød is a very common form of rye bread from Denmark. Rugbrød usually resembles a long brown extruded rectangle, no more than 12 cm high, and 30–35 cm wide, depending on the bread pan in which it is baked. The basic ingredient is rye flour which will produce a plain or "old-fashioned" bread of uniform, somewhat heavy structure, but the most popular versions today contain whole grains and often other seeds such as sunflower seeds, linseeds or pumpkin seeds. Most Danes eat rugbrød every day.

Lactobacillus acidophilus is a rod-shaped, Gram-positive, homofermentative, anaerobic microbe first isolated from infant feces in the year 1900. The species is most commonly found in humans, specifically the gastrointestinal tract, oral cavity, and vagina, as well as various fermented foods such as fermented milk or yogurt. The species most readily grows at low pH levels, and has an optimum growth temperature of 37 °C. Certain strains of L. acidophilus show strong probiotic effects, and are commercially used in dairy production. The genome of L. acidophilus has been sequenced.

Malolactic conversion is a process in winemaking in which tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. Malolactic fermentation is most often performed as a secondary fermentation shortly after the end of the primary fermentation, but can sometimes run concurrently with it. The process is standard for most red wine production and common for some white grape varieties such as Chardonnay, where it can impart a "buttery" flavor from diacetyl, a byproduct of the reaction.

Lactiplantibacillus plantarum is a widespread member of the genus Lactiplantibacillus and commonly found in many fermented food products as well as anaerobic plant matter. L. plantarum was first isolated from saliva. Based on its ability to temporarily persist in plants, the insect intestine and in the intestinal tract of vertebrate animals, it was designated as a nomadic organism. L. plantarum is Gram positive, bacilli shaped bacterium. L. plantarum cells are rods with rounded ends, straight, generally 0.9–1.2 μm wide and 3–8 μm long, occurring singly, in pairs or in short chains. L. plantarum has one of the largest genomes known among the lactic acid bacteria and is a very flexible and versatile species. It is estimated to grow between pH 3.4 and 8.8. Lactiplantibacillus plantarum can grow in the temperature range 12 °C to 40 °C. The viable counts of the "L. plantarum" stored at refrigerated condition (4 °C) remained high, while a considerable reduction in the counts was observed stored at room temperature.

Fructilactobacillus sanfranciscensis is a heterofermentative species of lactic acid bacteria which, through the production mainly of lactic and acetic acids, helps give sourdough bread its characteristic taste. It is named after San Francisco, where sourdough was found to contain the variety, though it is dominant in Type I sourdoughs globally. In fact, F. sanfranciscensis has been used in sourdough breads for thousands of years, and is used in 3 million tons of sourdough goods yearly.

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 bacteria, usually found in decomposing plants and milk products, produce lactic acid as the major metabolic end product of carbohydrate fermentation, giving them the common name lactic acid bacteria (LAB).

Limosilactobacillus reuteri is a lactic acid bacterium found in a variety of natural environments, including the gastrointestinal tract of humans and other animals. It does not appear to be pathogenic and may have health effects.

In cooking, proofing is a step in the preparation of yeast bread and other baked goods in which the dough is allowed to rest and rise a final time before baking. During this rest period, yeast ferments the dough and produces gases, thereby leavening the dough.

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 fermentation is a genus-specific trait. Lactobacillaceae include the homofermentative lactobacilli Lactobacillus, Holzapfelia, Amylolactobacillus, Bombilactobacillus, Companilactobacillus, Lapidilactobacillus, Agrilactobacillus, Schleiferilactobacillus, Loigolactobacillus, Lacticaseibacillus, Latilactobacillus, Dellaglioa, Liquorilactobacillus, Ligilactobacillus, and Lactiplantibacillus; the heterofermentative lactobacilli Furfurilactobacillus, Paucilactobacillus, Limosilactobacillus, Fructilactobacillus, Acetilactobacillus, Apilactobacillus, Levilactobacillus, Secundilactobacillus, and Lentilactobacillus, which were previously classified in the genus Lactobacillus; and the heterofermentative genera Convivina, Fructobacillus, Leuconostoc, Oenococcus, and Weissella which were previously classified in the Leuconostocaceae.

Levilactobacillus brevis is a gram-positive, rod shaped species of lactic acid bacteria which is heterofermentative, creating CO₂, lactic acid and acetic acid or ethanol during fermentation. L. brevis is the type species of the genus Levilactobacillus (previously L. brevis group), which comprises 24 species. It can be found in many different environments, such as fermented foods, and as normal microbiota. L. brevis is found in food such as sauerkraut and pickles. It is also one of the most common causes of beer spoilage. Ingestion has been shown to improve human immune function, and it has been patented several times. Normal gut microbiota L. brevis is found in human intestines, vagina, and feces.

Limosilactobacillus fermentum is a Gram-positive species in the heterofermentative genus Limosilactobacillus. It is associated with active dental caries lesions. It is also commonly found in fermenting animal and plant material including sourdough and cocoa fermentation. A few strains are considered probiotic or "friendly" bacteria in animals and at least one strain has been applied to treat urogenital infections in women. Some strains of lactobacilli formerly mistakenly classified as L. fermentum have since been reclassified as Limosilactobacillus reuteri. Commercialized strains of L. fermentum used as probiotics include PCC, ME-3 and CECT5716

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Limosilactobacillus mucosae is a rod shaped species of lactic acid bacteria first isolated from pig intestines. It has mucus-binding activity. The species is an obligate anaerobe, catalase-negative, doesn't form spores and is non-motile. Its type strain is S32T, and has been found to be most closely related to Limosilactobacillus reuteri.

Lactiplantibacillus fabifermentans is a member of the genus Lactiplantibacillus and a type of lactic acid bacteria (LAB), a group of Gram-positive bacteria that produce lactic acid as their major fermented end product and that are often involved in food fermentation. L. fabifermentans was proposed in 2009 as a new species, after the type strain LMG 24284^T has been isolated from Ghanaian cocoa fermentation. Analysis of the 16S rRNA gene sequence demonstrated that this species is a member of the Lactobacillus plantarum species group but further analysis demonstrated that it is possible to differentiate it from the nearest neighbors by means of DNA-DNA hybridization experiments, pheS sequence analysis, whole-cell protein electrophoresis, fluorescent amplified fragment length polymorphism analysis and biochemical characterization.

Secundilactobacillus collinoides is a rod shaped species of lactic acid bacteria found in fermenting apple juice or cider. It is part of the Lactobacillaceae family. It is Gram-positive, non-spore forming and non-motile prokaryote.

Kazachstania humilis is a species of yeast in the genus Kazachstania. It commonly occurs in sourdough and kefir cultures, along with different species of lactic acid bacteria. K. humilis is the most representative yeast species found in type I sourdough ecosystems. The effects of electric field strength, pulse width and frequency, or pulse shape is significant on the membranes of Candida humilis, but not very noticeable.

Limosilactobacillus is a thermophilic and heterofermentative genus of lactic acid bacteria created in 2020 by splitting from Lactobacillus. The name is derived from the Latin limosus "slimy", referring to the property of most strains in the genus to produce exopolysaccharides from sucrose. The genus currently includes 31 species or subspecies, most of these were isolated from the intestinal tract of humans or animals. Limosilactobacillus reuteri has been used as a model organism to evaluate the host-adaptation of lactobacilli to the human and animal intestine and for the recruitment of intestinal lactobacilli for food fermentations.

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