Lactic acid bacteria (LAB) play a significant role in the production of several food products for human consumption. Humans exploit and maximize the various benefits from LAB characteristics, especially in foods such as cheese, yogurt and other fermented products. More recently, research discovered that certain LAB, such as Lactococcus species,...
This thesis describes an analysis of the structure/function relationship of the
phage infection protein (Pip) in Lactococcus lactis. Pip is a protein required for phage
infection of L. lactis exclusively by phage c2 species. Pip, which shares no significant
homology to previously studied proteins, contains 6 hydrophobic regions; one residing...
In an attempt to determine the natural habitat of Streptococcus
lactis, Streptococcus cremoris, and Streptococcus diacetilactis 27
different species of vegetables, 18 species of fruits and many individual
cow raw milk samples were examined.
S. lactis was found to occur on potatoes, corn, cucumbers,
peas, beans, and cantaloupe. In each...
The bacteriophage receptor of lactococci was found on the cell
walls. A carbohydrate analysis of the cell walls from phage-resistant
mutants of L. lactis subsp. cremoris KR with reductions in phage binding
indicated that a loss of galactose correlated with a loss in binding
and infection of all phage tested:...
Most pathogens gain access to their host through mucosal surfaces. It is therefore desirable to develop mucosal vaccines that elicit an immune response to prevent this crucial first step in infection. Current mucosal vaccines are live attenuated strains of pathogens. More recent efforts have focused on the use of recombinant...
Novel mucosal vaccines (LL-M2e, LL-HAe, SG-HAe) were constructed from live, non-pathogenic Lactococcus lactis or Streptococcus gordonii that express conserved regions of HA or M2 antigens from avian influenza virus (AIV) A. All three vaccines evoked antigen-specific serum immunoglobulin G (IgG) responses in vaccinated chickens. The addition of the adjuvant cholera...
Strains of Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris with potential use in the food industry which had been previously isolated from nature using 16S rRNA probes were characterized for unique identifying traits and for attributes important for potential use in cheese manufacture. Strains of Lc. cremoris which...
Rapid acid production by lactic streptococci used in the manufacture of fermented dairy products is essential to the economy of the
industry and to the public health of consumers.
There remains to
developed, however, an adequate laboratory procedure to detect and
distinguish between slow and fast strains of these bacteria....
The malty flavor defect produced by Streptococcus lactis var.
maltigenes has been the cause of considerable economic distress to
various segments of the dairy industry. This study was conducted
in order to develop a more thorough understanding of the chemical
nature of this defect, and to formulate a synthetic malty...
Lactococcus lactis subsp. cremoris Ropy 352 and L. lactis
subsp. cremoris Hollandicus produce an exopolysaccharide (EPS) that
imparts commercially desirable textural and rheological properties
to fermented milk products. This ropy phenotype is expressed under
specific environmental conditions. A mucoid EPS phenotype, also
expressed under specific environmental conditions, but not involved...
Lactic Acid Bacteria (LAB), an important group of organisms in modern food production, are known to secrete a unique compound called exopolysaccharide (EPS). EPS is economically important because it enhances functional properties in food and may confer beneficial health effects to consumers. Novel strains of Lactococcus lactis, Streptococcus thermophilus, and...
Lactic acid bacteria (LAB) play a significant role in the production of several food products for human consumption. Humans exploit and maximize the various benefits from LAB characteristics, especially in foods such as cheese, yogurt and other fermented products. More recently, research discovered that certain LAB, such as Lactococcus species,...
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Lactococcus
Roberto A. Garcia III Mentor: Dr. Janine Trempy
Oregon State University; Department of
Lactic acid bacteria (LAB) play a significant role in the production of several food products for human consumption. Humans exploit and maximize the various benefits from LAB characteristics, especially in foods such as cheese, yogurt and other fermented products. More recently, research discovered that certain LAB, such as Lactococcus species,...
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Production in Lactococcus Roberto A. Garcia III Mentor: Dr. Janine Trempy Oregon State University;Department
Several lactic acid bacteria (LAB) of the Lactococcus, Lactobacillus,
Leuconostoc and Pediococcus genera were screened for inhibition of
food-borne pathogens and spoilage microorganisms in raw milk and
dairy products. Listeria monocytogenes was killed by Lactococcus
lactis subsp. lactis and Pediococcus pentosaceus due to their
production of bacteriocin-type inhibitors. Staphylococcus aureus...
The activity of chymosin, plasmin, and Lactococcus
lactis enzymes (cell envelope proteinase, intracellular
peptidases, and glycolytic enzymes) were determined
after 5-min exposures to pressures up to 800 MPa.
Plasmin was unaffected by any pressure treatment.
Chymosin activity was unaffected up to 400 MPa and
decreased at 500 to 800 MPa....
High pressure processing was investigated for controlling Cheddar cheese ripening. One-month- or 4-month-old Cheddar cheeses were subjected to pressures ranging from 200 to 800 MPa for 5 min at 25 °C. The number of viable Lactococcus lactis (starter) and Lactobacillus (nonstarter) cells decreased as pressure increased. Subsequent storage of the...
The work presented in this thesis is concerned with the
effect of several antibiotics and quaternary ammonium
sanitizers upon growth of lactic acid bacteria. Section I
reports the purification of beta-lactamase from Lactococcus
cremoris PR-108, by ion exchange chromatography, using the
chromogenic substrate pyridine-2-azo-p-dimethylaniline
(PADAC) as the enzymatic indicator. Section...
Nisin, bacteriocin produced by Lactococcus lactis, Nisin may have the potential to replace (or reduce) sulfiting agents traditionally added to wines to prevent the growth of spoilage lactic acid bacteria. This may be valuable since sulfites are believed to cause toxic responses in sensitive individuals. As a result, the U.S....
Dairy leuconostocs are frequently used as aroma-producing bacteria in mesophilic cultures used as starters for milk fermentations. Sixty Leuconostoc strains from different culture collections were studied taxonomically for species identification. Based on morphological, physiological and biochemical tests, twenty of these strains were typed as Leuconostoc mesenteroides ssp. cremoris (Leu. cremoris)....
Cheese is a fermented dairy product that is made from animal milk and is considered to be healthy food due to its available nutrients and potential probiotic characteristics. Since the microbes in the cheese matrix directly contribute to the quality and physicochemical properties of cheese, it is important to understand...
Pediococcus cerevisiae, Lactobacillus casei, Lactobacillus plantarum,
Leuconostoc mesenteroides, Lactococcus diacetylactis Bifidobacterium
bifidum, Leuconostoc oenos, and mixed cultures of Propionibacterium
shermanii and P. cerevisiae were used to ferment cucumber juice brine
(CJB) at 22-26°C for 1.5 months. Sugar utilization ranged from 14.6 to 86.1%.
pH of the fermented CJB ranged from...
Roles of lactic acid bacteria in flour pre-ferment and white
bread were investigated. Volatile compounds produced by the
organisms were identified using gas-liquid chromatography (GLC).
Lactic acid bacteria were isolated from domestic commercial
compressed yeast and active dry yeast. Numbers per gram of
sample were 10⁸ to 10⁹ in compressed...
The genes coding for the expression of a ropy exopolysaccharide responsible for commercially desirable textural and rhealogical traits in fermented milk products by a natural lactococcal ropy isolate were sought. Using a transposon mutagenesis vector, pGh9:ISS1, three mutants lacking expression of the ropy exopolysaccharide were isolated. One of the mutants...
Non-starter lactic acid bacteria (NSLAB) are found at low levels in fresh raw milk and are important to the dairy industry because of their potential impact on the flavor and texture of yogurt, sour cream, and cheese. The purpose of this study was to evaluate three methods for the identification...
Nisin, an antimicrobial peptide used in food preservation was
evaluated for thermal stability. Nisin retained antimicrobial
activity after having been heated at 121°C for seven hours.
Anhydrous nisin and concentrated nisin solutions (5-10 mg/ml) were
still active after having been heated up to 190°C or 230°C. When
exposed to high...
Given the many significant roles that bacteria play in modern food manufacturing, it is crucial that we have a fundamental understanding of how bacterial communities assemble and behave in the food manufacturing environment. The focus of this dissertation was to investigate both the spatial and temporal distributions of microbial communities...
Our objective is to develop methodologies to allow winemakers to precisely control the malotactic fermentation and to prevent spoilage of wines by undesirable bacteria.
Variation in cheese quality due to geographic location is important to cheese producers, consumers, and retailers on a global level. Understanding the impacts of geographic location of cheese plants may be useful to businesses for marketing, cost reduction, and quality improvement. Many aspects of variation due to geography have been...
Homebrewed ginger beer is a naturally fermented carbonated beverage that is flavored with ginger. Many people who make ginger beer at home, realized that it is a probiotic beverage which can aid in gastrointestinal health. The purpose of this thesis is to analyze the microbiome of homebrewed ginger beer in...
Cheddar Cheese samples (good cheese, weak cheese, cheese made with pasteurized milk, cheese made with heat-shocked milk, cheese from production plant A, cheese from production plant B, cheese made with adjunct culture, and cheese made without adjunct culture), were evaluated during the ripening stage. Proteolysis was studied by a fractionation...
Listeria monocytogenes contamination continues to pose challenges for the food industry and there is demand for effective methods of food preservation and protection that can also be considered clean label. A promising source of antilisterial compounds may be sourced from bacteria that produce novel byproducts. Ribosomally synthesized and post-translationally modified...
Lactobacilli are microorganisms with many applications in the
fermented food and dairy industries. In addition to the actual
fermentation of food products, lactobacilli are involved in the
metabolic breakdown of lactose in dairy products, enabling a large
population of lactose-intolerant humans to ingest milk. Lactobacilli
are also used as health...
Eight foodborne pathogenic and spoilage Gram-positive bacteria were
evaluated for their spontaneous resistance frequencies to the peptide
antimicrobial nisin. In brain heart infusion (BHI) medium, nisin resistance
frequencies were in the range of l06 to l08 when exposed to nisin at
concentrations 2 to 4 times the minimal inhibitory concentrations....
This study investigated potential application of lactic acid bacteria (LAB) in depuration for
reducing Vibrio parahaemolyticus in oysters. Lactobacillus plantarum ATCC 8014, which
exhibited strong bactericidal effects against V. parahaemolyticus in vitro, was added to artificial
seawater for depuration of Pacific oysters (Crassostrea gigas) inoculated with V.
parahaemolyticus BE 98-2029...
Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit to the host”. A wide variety of putative probiotics exist on the market; however, clinical evidence of their efficacy is lacking. Probiotics have been previously used in the treatment of metabolic diseases like type...
Whey protein is a functional food comprised of numerous bioactive peptides and proteins, including glycomacropeptide (GMP), a hydrophilic casein peptide that separates with the whey fraction during cheesemaking. GMP has a unique amino acid composition, making it a viable nutritional therapy in disorders where certain amino acids are implicated, while...
The objective of this study was to identify aroma volatiles in sweet whey powder. Volatiles were isolated by solvent extraction and solvent assisted flavor evaporation. Fractionation was followed to separate acidic volatiles from nonacidic volatiles. Gas chromatography/olfactometry and gas chromatography-mass spectrometry were used for the identification ofaroma compounds. Osme methodology...
Antimicrobial coatings used to reduce the risk of infection caused by tissue-contacting medical devices must address specific biocompatibility requirements including prevention of thrombosis and rise of bacterial resistance. An antimicrobial-loaded poly(ethylene-oxide) (PEO) coating has been tentatively shown to be non-fouling with sustained antimicrobial activity. However, the presence of the antimicrobial,...
Cooling of freshly formed Cheddar
cheese is thought to be one of the processing
steps that requires tighter control
to achieve more uniform and consistent
product quality. Cheese samples, obtained
after pressing, were rapidly cooled
to 5, 15, 25, or 35°C. Commercial samples
and test cheese at 7, 30, 60,...
Nisin, a bactericidal polypeptide, has the potential to inhibit spoilage bacteria and control rnatolactic fermentation in wines. Nisin activity has previously been observed to remain stable in white wines but to decrease in red wines. This decrease is believed to be directly proportional to the concentration of polyphenolic compounds in...
Western diets are high in fat and sucrose and can influence behavior and gut microbiota. There is growing evidence that altering the microbiome can influence the brain and behavior. This study was designed to determine whether diet-induced changes in the gut microbiota could contribute to alterations in anxiety, memory or...
Agricultural and companion animals are integral to our way of life as they provide us with nourishment, financial resources, transportation, and companionship. However, pets, managed animals in the agricultural industry, as well as wild populations of food animals are all subject to health and mortality risks. The gut microbiome is...
Streptococcus gordonii (S. gordonii) is being developed as a Gram-positive
expression vector for the expression of heterologous proteins. This bacterial
expression system takes advantage of the natural pathway of protein export and
anchoring on the surface of the bacterium. The expression of heterologous proteins
relies on the homologous recombination of...
Lambic and other barrel-aged beer styles are gaining popularity in the United States and Europe and are often treated as a premium product that can command a premium price. However, these styles can be prone to spoilage during the barrel-aging process, which represents a significant time and product commitment by...
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Figure 4.16 Box and whisker plot of relative abundance of Lactococcus between sample time
Molecular biological approaches were used to study and interfere with the life
cycle of infectious hematopoietic necrosis virus (IHNV). These included the control
of IHN disease in rainbow trout by genetic immunization or interference in vitro by
synthesis of sense and antisense expression of the viral nucleocapsid (N) gene, and...
Using a systems biology approach, we discovered and dissected a three-way interaction between the immune system, the intestinal epithelium and the microbiota. We found that, in the absence of B cells, or of IgA, and in the presence of the microbiota, the intestinal epithelium launches its own protective mechanisms, upregulating...
Bitterness is a common flavor attribute of aged cheese, but excessive levels are a flaw leading to consumer rejection. Bitterness in cheese has been primarily associated with milk casein-derived peptides of medium size (500–3,000 Da) and relative hydrophobicity. Herein, we demonstrate a novel approach for the identification of bitter peptides...
Mold growth on cheddar-style cheese, though not a food safety issue, causes significant loss to the industry due to consumer rejection. For this reason, it is common for at-risk products, such as cheese shreds, to be coated with the mold inhibitor natamycin. While highly effective at extending shelf-life, preferences for...
Vibrio parahaemolyticus is a human pathogen which is prevalent in marine environment. Consumption of raw or undercooked seafood contaminated with V. parahaemolyticus can cause foodborne illness. This study investigated the application of probiotics in depuration for reducing V. parahaemolyticus in raw Pacific oysters (Crassostrea gigas) and the utilization of green...
Streptococcus gordonii is a bacterial species that naturally colonizes the oral cavity of most healthy humans. It resides in the mouth as an adherent to dental surfaces and, with few exceptions, does not cause disease in individuals it inhabits. It possesses qualities that encourage its use as a vector to...
Raw milk microbiome is important to food safety and security. However, understanding the complexities of how the dairy farm environment may affect the microbiome is difficult. Since there are a variety of operating parameters for dairy farmers to use on their farms, each farming environment is unique. What makes the...
The production of Cheddar cheese is a complex process with multiple potential sources of undesirable bacteria, including those that have negative impacts on product quality (spoilage organisms) and those that are used to evaluate sanitary conditions in the production environment (indicator organisms). The dairy industry commonly uses coliform bacteria as...
A year-long, bench-scale treatability study was performed to assess whether an activated sludge sequencing batch reactor could be used to treat an influent stream of 50/50 (v/v) municipal wastewater and landfill leachate to discharge standards established by the Oregon Department of Environmental Quality. One primary obstacle that was exposed during...
The traditional filter paper assay for saccharifying cellulase
originally described by M. Mandels et al (1976) has been modified to
make possible low activity determinations of Trichoderma
cellulases. The enzymatic activity appears to decline during a
prolonged incubation period if no precautions have been taken. By
means of adding bovine...
This thesis is compromised of two distinct formulation sections, which are described below:
New compression-coated tablet formulations were developed for amoxicillin/clavulanate. Amoxicillin in an outer coat was separated from clavulanic acid in a core tablet by inactive ingredients in a middle coat. A chewable compression-coated tablet formulation with 50% stearic...
A moderate high-pressure processing (HPP) treatment is proposed to accelerate the shredability of Cheddar cheese. High pressure processing (345 and 483 MPa for 3 and 7 min) applied to unripened (1 d old) stirredcurd Cheddar cheese yielded microstructure changes that differed with pressure level and processing time. Untreated and pressure-treated...
High hydrostatic pressure (HHP) affects the pH of weak acids due to an increased degree of acid dissociation while under pressure. The temporary pH reduction by high pressure in such a case may influence the barotolerance of microorganisms. The objective of this study was to determine the impact of weak...
CodY is known to regulate various virulence properties in several Gram-positive bacteria but has not yet been studied
in the important histotoxic and intestinal pathogen Clostridium perfringens. The present study prepared an isogenic codY-null
mutant in C. perfringens type D strain CN3718 by insertional mutagenesis using the Targetron system. Western...
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protease production significantly increases after inacti-
vation of the codY gene in Lactococcus lactis (15
The concept of terroir is commonly used as marketing tool to highlight unique characteristics of regional food products, however there is little scientific evidence of terroir pertaining to cheese. The purpose of this research was to investigate the potential impact of milk origin, pasteurization, and commingling on the sensorial, chemical,...
In this study, we developed a simple and efficient Bacillus subtilis genome editing method in which targeted gene(s) could be inactivated by single-stranded PCR product(s) flanked by short homology regions and in-frame deletion could be achieved by incubating the transformants at 42 degrees C. In this process, homologous recombination (HR)...
Infections in hospitals account for over 100,000 deaths per year. These infections occur at the
hospital from complications following bacterial adhesion to intravenous catheters, coronary
stents and other implanted devices. Another common problem is protein adsorption to the
surface of the device and subsequent blood clotting. Methods for combating these...
The opportunistic pathogen Pseudomonas aeruginosa possesses two LuxR-LuxI
type quorum-sensing systems that use diffusible acyl-homoserine lactone molecules to
autoinduce and coordinate expression of multiple virulence factors. We conducted a highthroughput
screen for mutants deficient in skim-milk proteolysis—a quorum-sensing
dependent phenotype—using a nonredundant transposon-insertion library representing
most nonessential genes in P....
The fecal flora of healthy bottle or breast-fed infants was
examined for the presence of Bifidobacterium. Identification was
based on the presence of fructose-6-phosphate phosphoketolase,
which is found only in these bacteria. No bifidobacteria were
recovered from bottle-fed infants. However, bifidobacteria were
readily isolated from 15 day to 3 month...
Proteins are the metabolic machines of the cell and as such, the study of proteins could illuminate the dominant biological activities that are occurring within cells and reveal how an organism interacts with its environment. Here, we used proteomic techniques to study the abundant marine bacterium SAR11 both as an...
Vibrio coralliilyticus (Vcor) is a bacterial pathogen that is well adapted to shellfish hatcheries and is very pathogenic to the larvae of the Pacific oyster Crassostrea gigas. Vcor has been associated with several large scale larval mortality events in the Pacific Northwest that interrupt the supply of seed oysters available...
The present investigation was undertaken to characterize a
number of strains of Lactobacillus bulgaricus and Streptococcus
thermophilus intended for use by a commercial starter supply
company. Thorough characterization of each culture was required in
order to combine compatible strains so that their usefulness in
Mozzarella cheese manufacture would be maximized....
Lactose intolerance is a common food intolerance that occurs because of a post-weaning deficiency of lactase, an enzyme that cleaves the glyosidic bond of lactose. About 75% of the world's population is lactose intolerant. Common symptoms of lactose intolerance are abdominal pain, bloating and diarrhea. ~25% of the world’s population...
Victoria blight of oats (Avena sativa) is caused by the fungus, Cochliobolus victoriae, which produces the toxin, victorin. Victorin production is required for pathogenicity of the fungus. In oats, sensitivity to the toxin and susceptibility to the pathogen is conditioned by a dominant allele at the 1'b locus, while oats...
Microbial electrochemical systems (MESs) have attracted much research attention in recent years due to their promising applications in renewable energy generation, bioremediation, and wastewater treatment. In a MES, microorganisms interact with electrodes via electrons, catalyzing oxidation and reduction reactions at the anode and the cathode.
The bacterial community of a...
β-lactoglobulin (β-Lg), bovine serum albumin (BSA), α-lactalbumin
(α-Lac), and β-casein were adsorbed onto
silanized silica surfaces of low and high hydrophobicity
for 8 h, and β-Lg and BSA for 1 h. The surfaces were
incubated in buffer for 0, 5, 10, or 15 h and then contacted
with Listeria monocytogenes...
Sweet whey powder is mainly used as an ingredient in foods and has a potential for increased use with the development of new foods. In view of the many whey powder producers, there is need to establish the quality of the whey powders currently on the market in terms of...
Aquifers are an important storage location and source of fresh groundwater. They may become polluted by a number of contaminants including mobile divalent radionuclides such as strontium-90 which is a byproduct of uranium fission. A method for remediating such divalent radionuclides is sequestration through co-precipitation into calcium carbonate. Calcium carbonate...
Ammonia oxidation is the first and rate-limiting step in nitrification and is dominated by two distinct groups of microorganisms in soil: ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). AOA are often more abundant than AOB and dominate activity in acid soils. The mechanism of ammonia oxidation under acidic conditions has...
This study was undertaken to determine the role Leuconostoc
citrovorum may play in carbon dioxide production in milk. The
ability of L. citrovorum strains to produce gas was studied by two
methods. A qualitative method used visual measurement of gas where
an agar plug was forced up the neck of...
Dietary selenium (Se) alters whole-blood Se concentrations in sheep, dependent upon Se source and dosage administered, but little is known about effects on immune function. We used footrot (FR) as a disease model to test the effects of supranutritional Se supplementation on immune function. To determine the effect of Se-source...
Nisin is an antibacterial peptide, which when adsorbed
on a surface can inhibit bacterial adhesion and viability.
The ability of noncovalently immobilized nisin to withstand
exchange by the milk proteins bovine serum albumin, β-lactoglobulin, α-lactalbumin, and β-casein on surfaces that
had been silanized with dichlorodiethylsilane to exhibit
high and low...
Streptomycin resistance in both gram-positive and gram-negative bacteria is usually caused by a single mutation in the rpsL gene. The rpsL gene encodes the S12 protein of the ribosomal complex. The rpsL genes of various bacteria have consensus regions in their sequences. Primers were designed from these consensus pockets and...
Varying concentrations of the food preservatives nisin and lysozyme were adsorbed onto glass surfaces chemically modified to exhibit different degrees of hydrophobicity. The antimicrobial activity of the adsorbed preservatives was evaluated by documenting the ability of Listeria monocytogenes to adhere and grow on the glass surfaces. A bioluminescence protocol was...
The effects of various pressure treatments (OK, 30K, 60K, 75K psig) and packing medium (water or cocktail sauce) on shucked oysters were investigated. The pH, moisture content, microbiological tests (including aerobic plate count (APC) and anaerobic plate count (ANPC)), enzyme assays (i.e. α-amylase, β-amylase, lipase and peroxidase activities) were conducted...
Published May 1993. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Pseudomonas aeruginosa is a ubiquitous environmental microbe, opportunistic pathogen, and a highly social organism. P. aeruginosa utilizes a wide array of cooperative behaviors to adapt to the environmental conditions around it. These behaviors include quorum sensing (QS), a form a cell-to-cell signaling that coordinates the expression of secreted products in...
Microscopic organisms inhabit virtually every niche on this planet, where they perform functions vital to all life on earth. Accordingly, humans host a complex community of microorganisms (i.e. the gut microbiome) that inhabit the gastrointestinal tract and modulate host physiology. Insight into the specific mechanisms through which gut microbes influence...
Cell-cell communication in bacteria is understood to facilitate the coordination of population-wide cooperative behavior in the form of concerted gene expression. The opportunistic pathogen Pseudomonas aeruginosa uses such a communication mechanism to regulate a large group of genes important to virulence strategies in this bacterium. This general mechanism of communication...
Corals have multiple roles in maintaining ocean health and are some of the world’s most diverse ecosystems. The coral animal is host to a multitude of taxa, including symbiotic dinoflagellate algae, fungi, bacteria, protists, and viruses. Environmental stressors and disease agents can perturb the delicate balance of the coral host...
Rapid degradation of certain short lived "timing" proteins is
an effective mechanism for cells to control important regulatory
pathways. The mechanisms by which regulatory proteases
recognize their substrates are not well understood. Escherichia coli
Lon, an energy dependent protease highly conserved in many
prokaryotes and eukaryotes provides a model system...
The purpose of this study was to identify antimutagens in yogurt active against the
experimental colon carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Our
initial experiments showed that acetone extracts of yogurt, or milk fermented by various
lactic acid bacteria were antimutagenic against MNNG and 3,2'-dimethyl-4-aminobiphenyl
(DMAB) in the Ames test (Salmonella typhimurium TA...
