Lactobacillus fermentum
Encyclopedia
Lactobacillus fermentum is a Gram-positive
species of bacterium in the genus Lactobacillus
. It is associated with active dental caries
lesions. It is also commonly found in fermenting animal and plant material. It has been found in sourdough
. 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 classified as Lactobacillus fermentum (such as RC-14) have since been reclassified as Lactobacillus reuteri
. Commercialized strains of L. fermentum used as probiotics include PCC and ME-3.
. Species in this genus are used for a wide variety of applications. These applications include food and feed fermentation. It has been found that some strains for Lactobacillus fermentum have natural resistances to certain antibiotics and chemotherapeutics. They are considered potential vectors of antibiotic resistance
genes from the environment to humans or animals to humans.
Lactobacillus fermentum can also be a normal inhabitant of the human intestinal tract and some strains have been associated with cholesterol
metabolism.
is considered a probiotic
by meeting certain characteristics, such as being of human origin, non-pathogenic, having high resistance to passing through the intestine, and being beneficial to the immune system. In general, they are seen as beneficial to the host’s body and the human health. Lactobacillus fermentum has been identified as potential probiotic
.
The use of gut microbes as probiotics in food is aimed towards preventing and treating various health problems. Among these health problems allergies, neoplastic growth, and inflammatory bowel disease are included. Recent areas of study have focused on the influence of probiotics on metabolic functions of their host. One area has been the metabolism of cholesterol
by LABs acting as probiotics. Research has shown that Lactobacillus species have been proven to remove cholesterol in vitro
through various ways such as assimilation, binding to the surface cells, and incorporation into cellular membranes.
concentration solutions revealed that it has a strong pH tolerance by its ability to grow and survive a few hours after being incubated in a 3-pH level solution. Strains of Lactobacillus fermentum have also been tested in different bile
concentrations and demonstrated to have good bile tolerance when incubated with 3 g L-1 of bile salt. The pH and bile tolerance that L. fermentum demonstrates is significant in terms of its consideration as a probiotic
. It has to be strong enough to survive the stresses of the digestive system. The stomach has a pH between 1.5 and 3, and the upper intestine contains 3-5 g L-1 of bile. Lactobacillus fermentum has been found to survive in these conditions further supporting the idea that it can act as a probiotic.
is by its ability to reduce cholesterol levels. Tests conducted using several strains of Lactobacillus and cholesterol broths demonstrated that lactobacillus fermentum had the largest removal of cholesterol. One of the mechanisms by which L. fermentum may remove cholesterol through in vivo is by the absorption of cholesterol, which as a result accelerates cholesterol metabolism. Another method is by the incorporation of cholesterol in the host body into its cell membrane or walls. This would also increase resistance of the bacterial cell membranes to environmental challenge. A third mechanism is by causing the body to consume more cholesterol. L. fermentum would interfere with the recycling of bile salt and facilitate its elimination, which as a result would increase the demand for bile salt made from cholesterol.
and antioxidative probiotic. This strain of Lactobacillus fermentum was discovered from the analysis of human fecal samples in 1994. One of the important characteristics of a probiotic microbe is the tolerance to conditions in the digestive tract. Tests conducted on the ME-3 strain in different bile
concentrations found that it was able to survive without large loss in numbers. It has also been found that Lactobacillus fermentum ME-3 has a tolerance to survive drops of pH levels. It can withstand a drop in values from 4.0 to 2.5 without decreasing in numbers. These characteristics of tolerance to bile concentrations and pH levels serve to classify ME-3 as a probiotic
.
Lactobacillus fermentum ME-3 has also been found to have the capability to suppress mainly gram-negative bacteria. To a lesser extent, ME-3 has also been observed to be able to suppress Enterococci and Staphylococcus aureus. This would serve a beneficial purpose to the host. ME-3 has several antimicrobial
characteristics. These include acetic, lactic and succinic acids, and putrescine. Research on the antioxidant properties of strain ME-3 in soft cheese products revealed that it prevented spoilage.
Experimentation has also been conducted on the consumption of the ME-3 strain. The consumption had a positive influence on the microbiota of the gut. Volunteers were given goat milk fermented by strain ME-3 and capsulated ME-3. After three weeks analysis of fecal samples revealed that the ME-3 strain increased the number of beneficial Lactobacilli in comparison to those who were given non-fermented milk,
Properties of the strain ME-3 can serve to classify it as a probiotic
that has the ability to protect its host against food-derived infections and also help in the prevention of oxidative damage of food. Its multi-abilities have been tested and proven. Mice treated with a combination of ofloxacin and ME-3 revealed a reduction in liver and spleen granulomas of Salmonella thphimurium.
have been considered safe because of their association with food and because they are normal inhabitants of the human microflora. They have also been identified to have a low pathogenic potential further reinforcing the idea that they are safe microbes.
Recent research in regards to the safety of Lactobacillus fermentum has been carried out on mice. Mice were fed (intragastrically) different concentrations of Lactobacillus fermentum while a control group was also observed. After twenty-eight days blood samples were taken from the mice and analyzed. There was no health difference observed between the control mice and those fed Lactobacillus fermentum in terms of blood biochemistry, protein, albumin, glucose, and cholesterol. Also no negative side effects during the experiment such as change in body weight, feed intake, or clinical signs such as diarrhea and ruffled fur, were observed. The indigestion of Lactobacillus fermentum in mice appeared safe which led to further support that the use of lactobacillus fermentum in food is also safe.
, it must not contain any transferable resistant genes. If a resistance gene is transferable, it could lessen the effect of the use of antibiotics. Out of ten common antibiotic
genes that were tested (gatamicin, cefazolin, penicillin, trimethoprim/sulfmethoxazole, ampicillin, carbenicillin, erythromycin, amikacin, chloramphenicol, and norfloxacin), Lactobacillus fermentum was found to only be resistant to amikacin and norfloxacin. Others studies have reported that most LABs are also resistant to these antibiotics, which led to the conclusion that it was a common characteristic of LABs. The resistance to these antibiotics can be considered natural or intrinsic. So far no observed Lactobacillus fermentum strains have been observed to have transferable resistance or acquired resistance genes
spp., Shigella
spp., and urinary tract infections that are caused by E. coli and Staphylococcus
spp. Also the introduction of Lactobacillus fermentum strains such as ME-3 in goat milk revealed that it was actually favorable to the host, resulting in an increase in number of beneficial Lactobacilli.
genus have been identified to be the causative organisms. Research was carried out to observe the chemical constituents of tomato juice that stimulate the growth of bacteria that are responsible for the spoilage. These bacteria can resist high temperatures. A strain of Lactobacillus fermentum was extracted from a tomato juice concentrate. Meanwhile, eight different tomato juice mixtures were heated and the survival rate of Lactobacillus fermentum was measured. It was concluded that pectins are the main tomato juice constituents that protect the bacteria cells against destruction from heating. The breakdown of pectin from enzymic action would make the bacteria cells more susceptible to heat. However, it was found in previous research that heating had inactivated natural pectolytic enzymes and therefore Lactobacillus fermentum remained heat resistant. Heat resistance has also been found to correlate with the medium in which the bacteria are cultured, the better the medium used will result in a higher resistance to heat.
against clinically important agents by using broth dilution tests. Different strains of Lactobacillus fermentum demonstrated uniform resistance patterns demonstrating resistance to glycopeptide vancomycin and to tetracycline.
resistant properties, other studies have demonstrated that lactobacillus fermentum is sensitive to some common antibiotics such as gentamicin, cefazolin, penicillin, trimethoprim/sulfamethoxazole, ampicillin, carbenicillin, erythromycin, amikacin, and cholorampehnicol.
Gram-positive
Gram-positive bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink...
species of bacterium in the genus Lactobacillus
Lactobacillus
Lactobacillus is a genus of Gram-positive facultative anaerobic or microaerophilic rod-shaped bacteria. They are a major part of the lactic acid bacteria group, named as such because most of its members convert lactose and other sugars to lactic acid. They are common and usually benign...
. It is associated with active dental caries
Dental caries
Dental caries, also known as tooth decay or a cavity, is an irreversible infection usually bacterial in origin that causes demineralization of the hard tissues and destruction of the organic matter of the tooth, usually by production of acid by hydrolysis of the food debris accumulated on the...
lesions. It is also commonly found in fermenting animal and plant material. It has been found in sourdough
Sourdough
Sourdough is a dough containing a Lactobacillus culture, usually in symbiotic combination with yeasts. It is one of two principal means of biological leavening in bread baking, along with the use of cultivated forms of yeast . It is of particular importance in baking rye-based breads, where yeast...
. A few strains are considered probiotic
Probiotic
Probiotics are live microorganisms thought to be beneficial to the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host"...
or "friendly" bacteria in animals and at least one strain has been applied to treat urogenital infections in women. Some strains of lactobacilli formerly classified as Lactobacillus fermentum (such as RC-14) have since been reclassified as Lactobacillus reuteri
Lactobacillus reuteri
Lactobacillus reuteri is a Gram-positive bacterium that naturally inhabits the gut of mammals and birds. First described in the early 1980s, some strains of L. reuteri are used as probiotics. BioGaia AB in Sweden owns several commercially important strains and a large number of different patents...
. Commercialized strains of L. fermentum used as probiotics include PCC and ME-3.
Characteristics
Lactobacillus fermentum belongs to the genus LactobacillusLactobacillus
Lactobacillus is a genus of Gram-positive facultative anaerobic or microaerophilic rod-shaped bacteria. They are a major part of the lactic acid bacteria group, named as such because most of its members convert lactose and other sugars to lactic acid. They are common and usually benign...
. Species in this genus are used for a wide variety of applications. These applications include food and feed fermentation. It has been found that some strains for Lactobacillus fermentum have natural resistances to certain antibiotics and chemotherapeutics. They are considered potential vectors of antibiotic resistance
Antibiotic resistance
Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic. While a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs, genes that confer resistance can be transferred between bacteria in a...
genes from the environment to humans or animals to humans.
Lactobacillus fermentum can also be a normal inhabitant of the human intestinal tract and some strains have been associated with cholesterol
Cholesterol
Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...
metabolism.
Probiotic
A microorganismMicroorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...
is considered a probiotic
Probiotic
Probiotics are live microorganisms thought to be beneficial to the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host"...
by meeting certain characteristics, such as being of human origin, non-pathogenic, having high resistance to passing through the intestine, and being beneficial to the immune system. In general, they are seen as beneficial to the host’s body and the human health. Lactobacillus fermentum has been identified as potential probiotic
Probiotic
Probiotics are live microorganisms thought to be beneficial to the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host"...
.
The use of gut microbes as probiotics in food is aimed towards preventing and treating various health problems. Among these health problems allergies, neoplastic growth, and inflammatory bowel disease are included. Recent areas of study have focused on the influence of probiotics on metabolic functions of their host. One area has been the metabolism of cholesterol
Cholesterol
Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...
by LABs acting as probiotics. Research has shown that Lactobacillus species have been proven to remove cholesterol in vitro
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...
through various ways such as assimilation, binding to the surface cells, and incorporation into cellular membranes.
pH and Bile Tolerance
Testing of Lactobacillus fermentum against different pHPH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
concentration solutions revealed that it has a strong pH tolerance by its ability to grow and survive a few hours after being incubated in a 3-pH level solution. Strains of Lactobacillus fermentum have also been tested in different bile
Bile
Bile or gall is a bitter-tasting, dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the process of digestion of lipids in the small intestine. In many species, bile is stored in the gallbladder and upon eating is discharged into the duodenum...
concentrations and demonstrated to have good bile tolerance when incubated with 3 g L-1 of bile salt. The pH and bile tolerance that L. fermentum demonstrates is significant in terms of its consideration as a probiotic
Probiotic
Probiotics are live microorganisms thought to be beneficial to the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host"...
. It has to be strong enough to survive the stresses of the digestive system. The stomach has a pH between 1.5 and 3, and the upper intestine contains 3-5 g L-1 of bile. Lactobacillus fermentum has been found to survive in these conditions further supporting the idea that it can act as a probiotic.
Cholesterol Reduction
One of the ways in which Lactobacillus fermentum has been seen as a probioticProbiotic
Probiotics are live microorganisms thought to be beneficial to the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host"...
is by its ability to reduce cholesterol levels. Tests conducted using several strains of Lactobacillus and cholesterol broths demonstrated that lactobacillus fermentum had the largest removal of cholesterol. One of the mechanisms by which L. fermentum may remove cholesterol through in vivo is by the absorption of cholesterol, which as a result accelerates cholesterol metabolism. Another method is by the incorporation of cholesterol in the host body into its cell membrane or walls. This would also increase resistance of the bacterial cell membranes to environmental challenge. A third mechanism is by causing the body to consume more cholesterol. L. fermentum would interfere with the recycling of bile salt and facilitate its elimination, which as a result would increase the demand for bile salt made from cholesterol.
Lactobacillus fermentum ME-3
The strain Lactobacillus fermentum ME-3 has recently been discovered and identified as an antimicrobialAntimicrobial
An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...
and antioxidative probiotic. This strain of Lactobacillus fermentum was discovered from the analysis of human fecal samples in 1994. One of the important characteristics of a probiotic microbe is the tolerance to conditions in the digestive tract. Tests conducted on the ME-3 strain in different bile
Bile
Bile or gall is a bitter-tasting, dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the process of digestion of lipids in the small intestine. In many species, bile is stored in the gallbladder and upon eating is discharged into the duodenum...
concentrations found that it was able to survive without large loss in numbers. It has also been found that Lactobacillus fermentum ME-3 has a tolerance to survive drops of pH levels. It can withstand a drop in values from 4.0 to 2.5 without decreasing in numbers. These characteristics of tolerance to bile concentrations and pH levels serve to classify ME-3 as a probiotic
Probiotic
Probiotics are live microorganisms thought to be beneficial to the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host"...
.
Lactobacillus fermentum ME-3 has also been found to have the capability to suppress mainly gram-negative bacteria. To a lesser extent, ME-3 has also been observed to be able to suppress Enterococci and Staphylococcus aureus. This would serve a beneficial purpose to the host. ME-3 has several antimicrobial
Antimicrobial
An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...
characteristics. These include acetic, lactic and succinic acids, and putrescine. Research on the antioxidant properties of strain ME-3 in soft cheese products revealed that it prevented spoilage.
Experimentation has also been conducted on the consumption of the ME-3 strain. The consumption had a positive influence on the microbiota of the gut. Volunteers were given goat milk fermented by strain ME-3 and capsulated ME-3. After three weeks analysis of fecal samples revealed that the ME-3 strain increased the number of beneficial Lactobacilli in comparison to those who were given non-fermented milk,
Properties of the strain ME-3 can serve to classify it as a probiotic
Probiotic
Probiotics are live microorganisms thought to be beneficial to the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host"...
that has the ability to protect its host against food-derived infections and also help in the prevention of oxidative damage of food. Its multi-abilities have been tested and proven. Mice treated with a combination of ofloxacin and ME-3 revealed a reduction in liver and spleen granulomas of Salmonella thphimurium.
Safety
In general, strains of LactobacillusLactobacillus
Lactobacillus is a genus of Gram-positive facultative anaerobic or microaerophilic rod-shaped bacteria. They are a major part of the lactic acid bacteria group, named as such because most of its members convert lactose and other sugars to lactic acid. They are common and usually benign...
have been considered safe because of their association with food and because they are normal inhabitants of the human microflora. They have also been identified to have a low pathogenic potential further reinforcing the idea that they are safe microbes.
Recent research in regards to the safety of Lactobacillus fermentum has been carried out on mice. Mice were fed (intragastrically) different concentrations of Lactobacillus fermentum while a control group was also observed. After twenty-eight days blood samples were taken from the mice and analyzed. There was no health difference observed between the control mice and those fed Lactobacillus fermentum in terms of blood biochemistry, protein, albumin, glucose, and cholesterol. Also no negative side effects during the experiment such as change in body weight, feed intake, or clinical signs such as diarrhea and ruffled fur, were observed. The indigestion of Lactobacillus fermentum in mice appeared safe which led to further support that the use of lactobacillus fermentum in food is also safe.
Transferable Resistance Genes
One important consideration to determine the safety of Lactobacillus fermentum is transferable resistant genes. In order for L. fermentum to be considered as a potential probioticProbiotic
Probiotics are live microorganisms thought to be beneficial to the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host"...
, it must not contain any transferable resistant genes. If a resistance gene is transferable, it could lessen the effect of the use of antibiotics. Out of ten common antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
genes that were tested (gatamicin, cefazolin, penicillin, trimethoprim/sulfmethoxazole, ampicillin, carbenicillin, erythromycin, amikacin, chloramphenicol, and norfloxacin), Lactobacillus fermentum was found to only be resistant to amikacin and norfloxacin. Others studies have reported that most LABs are also resistant to these antibiotics, which led to the conclusion that it was a common characteristic of LABs. The resistance to these antibiotics can be considered natural or intrinsic. So far no observed Lactobacillus fermentum strains have been observed to have transferable resistance or acquired resistance genes
Dairy Products
Experiments conducted by introducing the strain ME-3 of Lactobacillus fermentum into diary products as a probiotic ingredient revealed that it was able to suppress the reputed contaminants of food such as pathogenic SalmonellaSalmonella
Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...
spp., Shigella
Shigella
Shigella is a genus of Gram-negative, nonspore forming, non-motile, rod-shaped bacteria closely related to Escherichia coli and Salmonella. The causative agent of human shigellosis, Shigella causes disease in primates, but not in other mammals. It is only naturally found in humans and apes. During...
spp., and urinary tract infections that are caused by E. coli and Staphylococcus
Staphylococcus
Staphylococcus is a genus of Gram-positive bacteria. Under the microscope they appear round , and form in grape-like clusters....
spp. Also the introduction of Lactobacillus fermentum strains such as ME-3 in goat milk revealed that it was actually favorable to the host, resulting in an increase in number of beneficial Lactobacilli.
Heat Resistance
Although LABs have been associated with potential health advantages, they are also responsible for negative outcomes. They are the main organisms involved in the spoilage of tomato products. Species in the LactobacillusLactobacillus
Lactobacillus is a genus of Gram-positive facultative anaerobic or microaerophilic rod-shaped bacteria. They are a major part of the lactic acid bacteria group, named as such because most of its members convert lactose and other sugars to lactic acid. They are common and usually benign...
genus have been identified to be the causative organisms. Research was carried out to observe the chemical constituents of tomato juice that stimulate the growth of bacteria that are responsible for the spoilage. These bacteria can resist high temperatures. A strain of Lactobacillus fermentum was extracted from a tomato juice concentrate. Meanwhile, eight different tomato juice mixtures were heated and the survival rate of Lactobacillus fermentum was measured. It was concluded that pectins are the main tomato juice constituents that protect the bacteria cells against destruction from heating. The breakdown of pectin from enzymic action would make the bacteria cells more susceptible to heat. However, it was found in previous research that heating had inactivated natural pectolytic enzymes and therefore Lactobacillus fermentum remained heat resistant. Heat resistance has also been found to correlate with the medium in which the bacteria are cultured, the better the medium used will result in a higher resistance to heat.
Antibiotic Resistance
Studies have shown that L. fermentum has antibiotic resistances. DNA was isolated from Lactobacillus fermentum and tested for antibiotic resistanceAntibiotic resistance
Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic. While a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs, genes that confer resistance can be transferred between bacteria in a...
against clinically important agents by using broth dilution tests. Different strains of Lactobacillus fermentum demonstrated uniform resistance patterns demonstrating resistance to glycopeptide vancomycin and to tetracycline.
Drug Resistance Plasmids
Research done on Lactobacillus fermentum strains has revealed the existence of tetracycline and erythromycin resistance plasmids.Sensitivity to Antibiotics
While Lactobacillus fermentum has been found to have antibioticAntibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
resistant properties, other studies have demonstrated that lactobacillus fermentum is sensitive to some common antibiotics such as gentamicin, cefazolin, penicillin, trimethoprim/sulfamethoxazole, ampicillin, carbenicillin, erythromycin, amikacin, and cholorampehnicol.