Exemplar Abstract for Lactococcus lactis cremoris (Orla-Jensen 1919) Schleifer et al. 1986, Streptococcus lactis cremoris (Orla-Jensen 1919) Garvie and Farrow 1982 and Streptococcus cremoris Orla-Jensen 1919 (Approved Lists 1980).

2003 ◽  
Author(s):  
Charles Thomas Parker ◽  
Dorothea Taylor ◽  
George M Garrity
Keyword(s):  
Lactococcus Lactis ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris

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.

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.

Acid Production and Proteolytic Activity in Milk by Gamma-Irradiation Induced Mutants of Lactobacilli

1977 ◽  
Vol 40 (9) ◽  
pp. 600-602 ◽  
Author(s):  
JASJIT SINGH ◽  
B. RANGANATHAN
Keyword(s):  
Gamma Irradiation ◽  
Proteolytic Activity ◽  
Acid Production ◽  
Lactobacillus Casei ◽  
Amino Nitrogen ◽  
Lactobacillus Bulgaricus ◽  
Soluble Nitrogen ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Induced Mutants

Biochemical changes in selected gamma-irradiation induced mutants of Lactobacillus bulgaricus and Lactobacillus casei were examined. Cultures were tested after 24 h of incubation at 37 C for titratable and volatile acidities and proteolytic activity. The gamma-irradiation induced mutants exhibited 50–95% greater proteolytic activity than the unirradiated parent culutres. Some of the mutants produced greater titratable and volatile acidities in milk as compared to parent cultures. Two mutant cultures, Lb/G-1 from L. bulgaricus 59 and Lc/G-1 from L. casei RTS released significantly greater amounts of soluble nitrogen and amino nitrogen in whole casein and selected fractions than did parent cultures. Combining the mutant cultures with Streptococcus lactis C10 or Streptococcus cremoris C1 resulted in greater acid producing ability than that of the parent cultures mixed with the streptococci.

Growth of Streptococcus cremoris and Streptococcus lactis in a chemostat. Production of cells and survival of bacteria during frozen storage

1973 ◽  
Vol 19 (10) ◽  
pp. 1285-1295 ◽  
Author(s):  
I. J. McDonald ◽  
B. Reiter ◽  
P. L. Rogers
Keyword(s):  
Yeast Extract ◽  
Frozen Storage ◽  
Skim Milk ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Constant Ph ◽  
Limiting Nutrient

Streptococcus cremoris HP and Streptococcus lactis 829 were grown in chemostats in tryptone yeast extract broth and in supplemented 2% skim milk medium. In both media, lactose was the limiting nutrient. Cultures were grown at various dilution rates in media poised at constant pH and temperature and also at constant dilution rates in media controlled at different pH levels and temperatures. The effects of the various conditions of growth on production of bacteria, viable counts, and acid-producing activities of cells and on the ability of bacteria to survive subsequent frozen storage were determined. None of the conditions of growth tested had very pronounced effects on the ability of cells to survive or on the inability of cells to retain acid-producing activity after being frozen at −70 °C and stored at −40 °C.

Filamentous forms of Streptococcus cremoris and Streptococcus lactis. Observations on structure and susceptibility to lysis

1971 ◽  
Vol 17 (7) ◽  
pp. 897-902 ◽  
Author(s):  
I. J. McDonald
Keyword(s):  
Electron Micrographs ◽  
Cell Walls ◽  
Normal Cell ◽  
Filament Formation ◽  
Normal Cells ◽  
Base Content ◽  
Daughter Cells ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Dna Base

Filamentous cultures of Streptococcus cremoris and Streptococcus lactis were isolated from growth which formed in orifices of medium inlet tubes of chemostats. Filamentous variants were maintained by biweekly transfer in agar stab cultures. Bacteria from parent and filamentous cultures grown in broth had the same DNA base content and the same bacteriophage susceptibility. Electron micrographs showed that filamentous streptococci had apparently normal cell walls and slightly enlarged cross walls. Filaments appeared to result from failure of daughter cells to separate after division. Filamentous cells were less readily autolyzed and were less susceptible to lysis by Iysozyme than normal cells. The results suggest that filament formation in lactic streptococci was associated with lower autolysin activity.

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