Behavior of Listeria monocytogenes in the Presence of Lactic Acid Bacteria in an Agitated Medium with Internal pH Control

1991 ◽  
Vol 54 (3) ◽  
pp. 183-188 ◽  
Author(s):  
JANE M. WENZEL ◽  
ELMER H. MARTH
Keyword(s):  
Lactic Acid ◽  
Statistical Analysis ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Lactococcus Lactis ◽  
Ph Control ◽  
Lactococcus Lactis Subsp ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Internal Ph

An agitated medium with internal pH control (IPCM-2) was inoculated to contain Listeria monocytogenes (strain V7, Scott A or California) at ca. 103 CFU/ml and Streptococcus cremoris (Lactococcus lactis subsp. cremoris) or Streptococcus lactis (Lactococcus lactis subsp. lactis) at 0.25 or 1.0% The inoculated medium was incubated with shaking in a waterbath at 30°C for 30 h. L. monocytogenes and lactic acid bacteria were enumerated and pH was determined at appropriate intervals. The area on a figure between curves for the control and treatment and designated as the area of inhibition (AI) was calculated and used to quantify inhibition of each strain of L. monocytogenes for a particular set of conditions in IPCM-2. Statistical analysis of AI values calculated from data obtained at 6, 24, and 30 h of incubation revealed no significant (p < 0.05) difference in inhibition among the three strains of L. monocytogenes for each type of lactic streptococcus present. Streptococcus cremoris was significantly (0.01 < p < 0.05) more inhibitory to all three strains of L. monocytogenes than was S. lactis at 24 and 30 h of incubation. IPCM-2 is considered ready for use at a pH of 5.4 or less, which was reached between 12 and 15 h of incubation in samples containing 0.25 or 1.0% S. cremoris. Populations of L. monocytogenes in such samples were ca. 104 to 106 CFU/ml regardless of strain of Listeria or percentage of S. cremoris added as inoculum. In samples initially containing 0.25 or 1.0% S. lactis, pH 5.4 was not reached until after 18–24 h of incubation. At this point all three strains of L. monocytogenes had grown to ca. 105 CFU/ml regardless of percentage of S. lactis added as inoculum. Despite the inhibition seen, substantial numbers of the pathogen were present when the medium was ready for use.

Behavior of Listeria monocytogenes in Skim Milk during Fermentation with Mesophilic Lactic Starter Cultures

1988 ◽  
Vol 51 (8) ◽  
pp. 600-606 ◽  
Author(s):  
MICHELLE M. SCHAACK ◽  
ELMER H. MARTH
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Skim Milk ◽  
Starter Cultures ◽  
Plate Count ◽  
Inoculum Level ◽  
Plate Count Agar ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris

The ability of Listeria monocytogenes to grow and compete with mesophilic lactic acid bacteria was examined. Autoclaved skim milk was inoculated with 103 cells of L. monocytogenes (strain V7 or Ohio)/ml, and with 5.0, 1.0, 0.5 or 0.1% of a milk culture of either Streptococcus cremoris or Streptococcus lactis. Inoculated milks were fermented for 15 h at 21 or 30°C, followed by refrigeration at 4°C. Samples were plated on McBride Listeria Agar to enumerate L. monocytogenes and on either APT Agar or plate count agar to enumerate lactic acid bacteria. L. monocytogenes survived in all fermentations, and commonly also grew to some extent. Incubation at 30°C with 5% S. lactis as inoculum appeared to be the most inhibitory combination for strain V7, causing 100% inhibition in growth based on maximum population attained. S. cremoris at the 5.0% and 0.1% inoculum levels, was slightly less inhibitory to L. monocytogenes at 37°C, but it was slightly more inhibitory to L. monocytogenes at the 1.0% inoculum level than was S. lactis. In general, S. lactis reduced the pH of fermented milks more than did S. cremoris. The population of L. monocytogenes began to decrease before 15 h in only one test combination, which was use of a 5.0% inoculum of S. cremoris and 30°C incubation. In most instances, growth of the pathogen appeared to be completely inhibited when the pH dropped below 4.75.

scholarly journals Autochthonous Enterococcus durans PFMI565 and Lactococcus lactis subsp. lactis BGBU1–4 in Bio-Control of Listeria monocytogenes in Ultrafiltered Cheese

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1448
Author(s):  
Marina Ivanovic ◽  
Nemanja Mirkovic ◽  
Milica Mirkovic ◽  
Jelena Miocinovic ◽  
Ana Radulovic ◽  
...  
Keyword(s):  
Lactic Acid ◽  
High Temperature ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Lactococcus Lactis ◽  
Chemical Additives ◽  
Enterococcus Durans ◽  
Lactococcus Lactis Subsp ◽  
Bacteriocin Producer ◽  
Cheese Production

Nowadays, consumers are interested in cheese produced without chemical additives or high-temperature treatments, among which, protective lactic acid bacteria (LAB) cultures could play a major role. In this study, the aims were to isolate, identify and characterize antilisterial LAB from traditionally produced cheese, and utilize suitable LAB in cheese production. Among 200 isolated LAB colonies, isolate PFMI565, with the strongest antilisterial activity, was identified as Enterococcus durans. E. durans PFMI565 was sensitive to clinically important antibiotics (erytromicin, tetracycline, kanamycin, penicillin, vancomycin) and had low acidifying activity in milk. E. durans PFMI565 and the previously isolated bacteriocin producer, Lactococcus lactis subsp. lactis BGBU1–4, were tested for their capability to control Listeria monocytogenes in experimentally contaminated ultrafiltered (UF) cheeses during 35 days of storage at 4 °C. The greatest reductions of L. monocytogenes numbers were achieved in UF cheese made with L. lactis subsp. lactis BGBU1–4 or with the combination of L. lactis subsp. lactis BGBU1–4 and E. durans PFMI565. This study underlines the potential application of E. durans PFMI565 and L. lactis subsp. lactis BGBU1–4 in bio-control of L. monocytogenes in UF cheese.

Inhibition of Enteropathogenic Escherichia coli by Homofermentative Lactic Acid Bacteria in Skimmilk

1977 ◽  
Vol 40 (11) ◽  
pp. 754-759 ◽  
Author(s):  
J. F. FRANK ◽  
E. H. MARTH
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Starter Culture ◽  
Enteropathogenic Escherichia Coli ◽  
Plate Method ◽  
E Coli ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Plating Method

Inhibition of enteropathogenic Escherichia coli in skimmilk at 21 and 32 C by 0.25 and 2.0% of added Streptococcus lactis, Streptococcus cremoris, or a mixed strain starter culture was studied. After 15 h of fermentation, fermented milks were refrigerated at 7 C and then were tested periodically for survival of E. coli. Three methods for enumeration of E. coli during these fermentations were compared. They included trypticase soy agar (TSA) pour plates, violet red bile agar (VRB) pour plates, and TSA surface plating with a VRB overlay. Lactic cultures had similar inhibitory properties at 32 C, but there were differences at 21 C, with S. lactis being least inhibitory and the mixed strain culture most inhibitory. The VRB pour plate method gave poorest recovery of E. coli when fermentation was at 32 C and when fermented milks were refrigerated. The TSA surface plating method apparently allowed for recovery of injured E. coli cells and gave results similar to the TSA pour plate method.

Expression of mptC of Listeria monocytogenes induces sensitivity to class IIa bacteriocins in Lactococcus lactis

Microbiology ◽  
2004 ◽  
Vol 150 (8) ◽  
pp. 2663-2668 ◽  
Author(s):  
Manilduth Ramnath ◽  
Safia Arous ◽  
Anne Gravesen ◽  
John W. Hastings ◽  
Yann Héchard
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Lactococcus Lactis ◽  
Inhibitory Activity ◽  
Bacteriocin Activity ◽  
Phosphotransferase System ◽  
Enterocin A ◽  
Leucocin A

Sensitivity to class IIa bacteriocins from lactic acid bacteria was recently associated with the mannose phosphotransferase system (PTS) permease, , in Listeria monocytogenes. To assess the involvement of this protein complex in class IIa bacteriocin activity, the mptACD operon, encoding , was heterologously expressed in an insensitive species, namely Lactococcus lactis, using the NICE double plasmid system. Upon induction of the cloned operon, the recombinant Lc. lactis became sensitive to leucocin A. Pediocin PA-1 and enterocin A also showed inhibitory activity against Lc. lactis cultures expressing mptACD. Furthermore, the role of the three genes of the mptACD operon was investigated. Derivative plasmids containing various combinations of these three genes were made from the parental mptACD plasmid by divergent PCR. The results showed that expression of mptC alone is sufficient to confer sensitivity to class IIa bacteriocins in Lc. lactis.

BEHAVIOR OF SALMONELLA TYPHIMURIUM IN SKIMMILK DURING FERMENTATION BY LACTIC ACID BACTERIA1

1972 ◽  
Vol 35 (8) ◽  
pp. 482-488 ◽  
Author(s):  
H. S. Park ◽  
E. H. Marth
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Salmonella Typhimurium ◽  
Streptococcus Thermophilus ◽  
Mixed Cultures ◽  
Lactobacillus Bulgaricus ◽  
Complete Inactivation ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Incubation Temperatures

Skimmilk was inoculated with Salmonella typltimurium (approximately 103/ml) and with Streptococcus cremoris, Streptococcus lactis, mixtures of S. cremoris and S. lactis, Streptococcus diacetilactis, Streptococcus thermophilus, Lactobacillus bulgaricus, mixtures of S. thermophilus and L. bulgaricus, a mixture of L. helveticus and S. thermophilus, and Leuconostoc citrovorum. Inocula of lactic acid bacteria ranged from 0.25 to 5.0% and incubation temperatures from 21 to 42 C. Streptococcus cremoris, S. lactis, and mixtures of the two repressed growth but did not inactivate S. typhimurium during 18 hr of incubation at 21 or 30 C when the lactic inoculum was 0.25%. An increase in inoculum to 1% resulted in inactivation of S. typhimurium at 30 C by some of the mixed cultures. Both S. diacetilactis and L. citrovorum were less inhibitory to S. typhimurium than were S. cremoris or S. lactis. When added at the 1% level, Streptococcus thermophilus was more detrimental to S. typhimurium at 42 C than was L. bulgaricus. Mixtures of these two lactic acid bacteria, when added at levels of 1.0 and 5.0%, caused virtually complete inactivation of S. typhimurium during the interval between 8 and 18 hr of incubation at 42 C.

Preservation of Lactic Acid Bacteria on Anhydrous Silica Gel for Three Years

1983 ◽  
Vol 46 (8) ◽  
pp. 699-701 ◽  
Author(s):  
MARIA C. T. DE SILVA ◽  
MARIA A. TESSI ◽  
MARIA A. MOGUILEVSKY
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Silica Gel ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Helveticus ◽  
Lactobacillus Bulgaricus ◽  
Preservation Methods ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Negative Effect

This study, which covers three years of storage. analyzes the application of silica gel preservation methods to lactic acid bacteria widely used in yogurt and cheese fermentation. Strains of Streptococcus lactis, Streptococcus lactis subsp. diacetylactis, Streptococcus cremoris, Streptococcus thermophilus. Lactobacillus bulgaricus, Lactobacillus helveticus and a yogurt culture were adsorbed on anhydrous silica gel in screw-cap tubes or in ordinary test tubes which were subsequently flame-sealed under vacuum. During 3 years. the bacteria were tested for viability by incubation in sterile milk. All of the bacteria retained their acidifying activity, with the exception of the yogurt culture. Extending preservation for more than 2 years had a negative effect on the activity of the yogurt culture. Results obtained support the use of screw-cap tubes which, in general, were suitable to preserve suspensions of lactic acid bacteria adsorbed on anhydrous silica gel.

Behavior of Listeria monocytogenes in the Presence of Streptococcus lactis in a Medium with Internal pH Control

1990 ◽  
Vol 53 (11) ◽  
pp. 918-923 ◽  
Author(s):  
JANE M. WENZEL ◽  
ELMER H. MARTH
Keyword(s):  
Listeria Monocytogenes ◽  
Starter Culture ◽  
Ph Control ◽  
Experimental Conditions ◽  
Initial Inoculum ◽  
Dairy Foods ◽  
Streptococcus Lactis ◽  
Significant Difference ◽  
Internal Ph ◽  
Before And After

Growth of Listeria monocytogenes strains V7, Scott A, and California (initial inoculum 103/ml) at 21 or 30°C in the presence of Streptococcus Iactis (initial inoculum 0.25 or 1.0%) was determined using a medium with internal pH control (IPCM-1). The pH of the uninoculated medium (control) was 7.0 before and after incubation. Populations of L. monocytogenes in IPCM-1 without S. lactis after 30 h at 21°C were ca. 107/ml for strains V7 and Scott A and ca. 106/ml for strain California, and at 30°C they were ca. 108/ml for all three strains. When data were plotted, areas of graphs between curves representing controls and treatments were calculated to quantitate the extent of inhibition of L. monocytogenes caused by S. lactis. Each such area is called the “area of inhibition” (AI). Growth of the pathogen was inhibited by S. lactis; the degree was dependent on temperature and concentration of lactic culture and, in some instances, strain of Listeria. Greatest inhibition of each strain occurred with the largest inoculum of S. lactis and at the highest temperature. No significant difference (p>0.05) in AI or pH among the three strains was observed at 21°C. At 30°C, strain California was inhibited significantly more (p<0.05) than V7 or Scott A by both concentrations of S. lactis at 24 and 30 h of incubation. No significant difference (p>0.05) in pH was found at this temperature regardless of concentration of S. lactis or strain of Listeria. IPCM-1 inoculated with a lactic starter culture is ready for use at pH 5.5 after 15–18 h of incubation. Inhibition of Listeria was not complete at this pH under any of the experimental conditions. Substantial numbers of L. monocytogenes (103–105 CFU/ml) were present when this medium was ready for use to produce cultured dairy foods.

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