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.

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 Enterobacter Species and Hafnia Species in Skimmilk During Fermentation by Lactic Acid Bacteria

1980 ◽  
Vol 43 (9) ◽  
pp. 720-728 ◽  
Author(s):  
J. L. RUTZINSKI ◽  
E. H. MARTH
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Necessary Conditions ◽  
Starter Culture ◽  
Enterobacter Aerogenes ◽  
Starter Cultures ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Enterobacter Species ◽  
The Individual

Enterobacter cloacae, Enterobacter aerogenes and two strains of Hafnia sp. were cultured individually in skimmilk together with Streptococcus lactis, Streptococcus cremoris or with one of two commercial lactic starter cultures. Incubation was at 21 or 32 C, and the lactic culture inoculum was 0.25, 1.0 or 2.0%. Growth of E. cloacae and E. aerogenes was markedly inhibited by S. lactis and S. cremoris at 32 C, and less so at 21 C. The commercial starter cultures were less inhibitory than the individual lactic streptococci. An increase in inoculum of lactic acid bacteria was accompanied by an increase in inhibition of Enterobacter sp., especially at 32 C. Both strains of Hafnia were inhibited more by S. lactis than by S. cremoris and the commercial starter cultures. Incubation at 32 rather than 21 C and increasing the amount of added lactic starter culture increased inhibition of Hafnia sp. All of the test coliforms were partially or completely inactivated toward the end of the 15-h incubation, provided the necessary conditions prevailed.

Low-Temperature Activity of Lactic Streptococci Isolated from Cultured Buttermilk

1982 ◽  
Vol 45 (13) ◽  
pp. 1208-1211 ◽  
Author(s):  
STEVEN L. HOGARTY ◽  
JOSEPH F. FRANK
Keyword(s):  
Low Temperature ◽  
Skim Milk ◽  
Potential Effect ◽  
Starter Cultures ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Generation Times ◽  
Significant Difference ◽  
Selection Of

Psychrotrophic and mesophilic lactic streptococci were isolated from commercial cultured buttermilk to determine their potential effect on the quality of this product. These isolates consisted primarily of Streptococcus lactis subsp. diacetylactis, with S. lactis, Streptococcus cremoris, and Leuconostoc spp. also being present. Psychrotrophic isolates of S. lactis subsp. diacetylactis were compared to mesophilic isolates in regard to their ability to grow and reduce diacetyl in acidified milk (pH 4.7) incubated at 7°C. There was no significant difference detected in the ability of the two groups to reduce diacetyl (P<.05). The mesophilic isolates grew more rapidly in acidified refrigerated milk than did the psychrotrophs, indicating that the psychrotrophic isolates were more acid sensitive. The psychrotrophic isolates exhibited generation times of 9 to 11 h when grown in skim milk (pH 6.7) at 7°C. Both psychrotrophic and mesophilic strains of S. lactis subsp. diacetylactis could rapidly reduce diacetyl in refrigerated acidified milk. The results of this study suggest that procedures for selection of starter cultures for buttermilk manufacture should be improved.

Yogurt production from reconstituted skim milk powders using different polymer and non-polymer forming starter cultures

1993 ◽  
Vol 60 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Carmen Wacher-Rodarte ◽  
Marcia V. Galvan ◽  
Amelia Farres ◽  
Francisco Gallardo ◽  
Valerie M. E. Marshall ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Skim Milk ◽  
Starter Cultures ◽  
Synergic Effect ◽  
Total Solids ◽  
Total Milk ◽  
Solids Content ◽  
Milk Solids ◽  
Viscosity Polymer

SummaryUsing polymer producing (ropy) strains of lactic acid bacteria it was possible to reduce considerably the syneresis of yogurt, even with 12% total milk solids. The viscosities obtained with these strains were also similar to those obtained using normal strains and milk with 17% total solids content. The concentration of milk and the polymer produced by ropy starters had a synergic effect in increasing viscosity. Polymer production was not affected in most cases by milk concentration. One type of ropy culture (Wiesby) seemed to produce a different kind of polymer as it could not be determined by alcohol precipitation, in spite of being able to reduce syneresis and increase viscosity in yogurt. A limited number of yogurts were evaluated organoleptically, one prepared with a ropy starter strain (NCFB at 12, 14·5 and 17% total solids) and one prepared with a non-ropy strain (LL-I at 17% total solids). The results suggest that the ropy strain yogurts had different mouthfeel from the non-ropy strain yogurts; the most acceptable product overall was the ropy strain made with 12% total solids.

scholarly journals The Viability of Lactobacillus plantarum From Intestines of Laying Ducks Encapsulated With Arabic Gum and Skimmed Milk

2021 ◽  
Vol 16 (3) ◽  
pp. 190-199
Author(s):  
Badat Muwakhid ◽  
Anik Maunatin ◽  
Anif Mukaromah Wati
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Spray Drying ◽  
Skim Milk ◽  
Plate Count ◽  
Resistance Testing ◽  
Drying Process ◽  
Arabic Gum ◽  
Before And After ◽  
Skimmed Milk

The aim of this study was to evaluate the effect of the types of encapsulation materials, that is skimmed milk and Arabic gum on two probiotics Lactic Acid Bacteria (LAB), including L. plantarum DJ2 and L. plantarum DJ3. The methods of this study were separated into two stages that is probiotic resistance testing during the spray drying process and the viability of LAB after spray drying during storage of probiotic powder for one month at 4oC. Changes in the viability of LAB probiotics before and after the drying process using spray drying were determined by the total plate count. The viability of lactic acid bacteria (LAB) was observed every week for one month of storage at 4oC. The results showed that different encapsulation materials had significant different (P ≤ 0.05) on changes in resistance of probiotics powder during spray drying process. The use of Arabic gum could increase the resistance of probiotics during the spray drying process, meanwhile, the use of skimmed milk was better to be able to maintain the viability of dry probiotic powder both on L.plantarum DJ2 and L.plantarum DJ3 during storage. After four weeks of storage, there was mold and yeast in the skimmed milk and Arabic gum materials. In conclusion, both Arabic gum and skim milk could be used for encapsulation where storage of dry probiotic products is recommended during one month at 4 oC.

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.

scholarly journals In vitro evaluation of bacteriocin-like inhibitory substances produced by lactic acid bacteria isolated during traditional Sicilian cheese making

2016 ◽  
Vol 5 (1) ◽  
Author(s):  
Giusi Macaluso ◽  
Gerlando Fiorenza ◽  
Raimondo Gaglio ◽  
Isabella Mancuso ◽  
Maria Luisa Scatassa
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Salmonella Enteritidis ◽  
Raw Milk ◽  
Starter Cultures ◽  
Proteinase K ◽  
Alternative Methods ◽  
Diffusion Assay

Bacteriocins are antimicrobial proteins produced by bacteria that inhibit with a bactericidal or bacteriostatic mode of action, the growth of other bacteria. Many lactic acid bacteria (LAB) produce a high diversity of different bacteriocins. Bacteriocinogenic LAB are generally recognized as safe (GRAS) and useful to control the frequent development of pathogens and spoilage microorganisms; for this reason they are commonly used as starter cultures in food fermentations. In this study, the authors describe the results of a screening on 699 LAB isolated from wooden vat surfaces, raw milk and traditional Sicilian cheeses, for the production of bacteriocin-like inhibitory substances (BLIS), by comparing two alternative methods. The antagonistic activity of LAB and its proteinaceous nature were evaluated using the <em>spot on the lawn</em> and the <em>well-diffusion assay</em> and the sensitivity to proteolytic (proteinase K, protease B and trypsin), amylolytic (α-amylase) and lipolytic (lipase) enzymes. The indicator strains used were: <em>Listeria monocytogenes</em>, <em>Staphylococcus aureus</em>, <em>E. coli</em>, <em>Salmonella enteritidis</em>. A total of 223 strains (belonged to the species <em>Enterococcus</em> spp., <em>Lactobacillus</em> spp., <em>Pediococcus</em> spp., <em>Streptococcus</em> spp., <em>Leuconostoc</em> spp. and <em>Lactococcus lactis</em>) were found to inhibit the growth of <em>Listeria monocytogenes</em> by using the <em>spot on the lawn</em> method; only 37 of these were confirmed by using the well-diffusion assay. The direct addition of bacteriocin-producing cultures into dairy products can be a more practical and economic option for the improvement of the safety and quality of the final product.

Behavior of Listeria monocytogenes in the Presence of Flavobacteria in Skim Milk at 7 or 13°C

1991 ◽  
Vol 54 (9) ◽  
pp. 677-680 ◽  
Author(s):  
SEHAM A. FARRAG ◽  
ELMER H. MARTH
Keyword(s):  
Listeria Monocytogenes ◽  
Skim Milk ◽  
Mixed Cultures ◽  
Plate Count ◽  
Time Intervals ◽  
Plate Count Agar ◽  
Pure Cultures

Sterile samples of skim milk were inoculated with Listeria monocytogenes (strain Scott A, California, or V7), Flavobacterium lutescens or Flavobacterium species, or a combination of L. monocytogenes plus flavobacteria and incubated at 7 or 13°C for 8 weeks. McBride Listeria agar was used to determine populations of L. monocytogenes at 0, 7, 14, 28, 42, or 56 d, and plate count agar was used to enumerate flavobacteria at the same time intervals. Growth of L. monocytogenes was significantly (P&lt;0.05) enhanced during incubation at 7 or 13°C in mixed cultures with F. lutescens. When tested with Flavobacterium sp. ATCC 21429, numbers of L. monocytogenes decreased insignificantly (P&lt;0.05) in mixed cultures compared to pure cultures. L. monocytogenes did not affect growth of flavobacteria; also, no marked changes in pH of the milk were caused either by L. monocytogenes alone or by mixed cultures.

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