scholarly journals N6-(1-carboxyethyl)lysine formation by Streptococcus lactis. Purification, synthesis, and stereochemical structure.

1988 ◽  
Vol 263 (4) ◽  
pp. 2064-2069
Author(s):  
J Thompson ◽  
S P Miller
Keyword(s):  
Stereochemical Structure ◽  
Streptococcus Lactis

Nomenclature Abstract for Streptococcus lactis lactis (Lister 1873) Garvie and Farrow 1982.

2003 ◽  
Author(s):  
Charles Thomas Parker ◽  
Nicole Danielle Osier ◽  
George M Garrity
Keyword(s):  
Streptococcus Lactis

Inoculation of Citric Acid-Fermenting Bacteria into Raw Milk in Farm Bulk Tanks

1979 ◽  
Vol 42 (1) ◽  
pp. 51-54 ◽  
Author(s):  
C. H. WHITE ◽  
S. G. SHILOTRI
Keyword(s):  
Hydrogen Peroxide ◽  
Raw Milk ◽  
Federal Agencies ◽  
Health Departments ◽  
State Health ◽  
Toxic Agent ◽  
Streptococcus Lactis ◽  
Fermenting Bacteria ◽  
Viable Bacteria ◽  
Bulk Tank

Cultures of Streptococcus lactis subsp. diacetylactis and Leuconostoc cremoris were added together in the amount of 0.5% to raw milk in a farm bulk tank. This treatment did not significantly reduce the psychrotrophic or coliform population as hypothesized; however, the shelf-life was extended on products made from this raw milk by an average of 1 day. Also, the legal question of adding viable bacteria to the raw milk needs to be considered by state health departments and appropriate federal agencies. Since hydrogen peroxide is reported to be the toxic agent (to the psychrotrophs) released by the citrate fermenters, the obvious fact is noted that this agent can already be added to milk designed for cheese manufacture.

Constitutive nature of the enzymes of citrate metabolism inStreptococcus lactissubsp.diacetylactis

1981 ◽  
Vol 48 (3) ◽  
pp. 489-495 ◽  
Author(s):  
Timothy M. Cogan
Keyword(s):  
Acetolactate Synthase ◽  
Streptococcus Lactis ◽  
Citrate Metabolism ◽  
Citrate Lyase ◽  
In Cells

SummaryFour enzymes of citrate metabolism (viz. citrate lyase, acetolactate synthase, diacetyl reductase and acetoin reductase) were constitutively present in cells of several strains ofStreptococcus lactissubsp.diacetylactis. In strain DRC1, which was studied in detail, diacetyl reductase and acetoin reductase were partly repressed and acetolactate synthase partly induced by growth on citrate. The stage of growth also affected the formation of each enzyme. The buffer species affected the activity of acetolactate synthase, diacetyl reductase and acetoin reductase.

Behaviour ofStreptococcus lactisin heat treated (80 °C for 30 min) or sterilized cow's and ewe's milk

1983 ◽  
Vol 50 (3) ◽  
pp. 357-363 ◽  
Author(s):  
Francisco J. Chavarri ◽  
Jose A. Nuñez ◽  
Manuel Nuñez
Keyword(s):  
Acid Production ◽  
Generation Time ◽  
Buffer Capacity ◽  
Cow’S Milk ◽  
Cow's Milk ◽  
Vitamin Content ◽  
Streptococcus Lactis ◽  
Generation Times ◽  
Heat Treated ◽  
Ewe's Milk

SummaryGeneration times and acid production after 6 and 24 h by 20 strains ofStreptococcus lactisof dairy origin were determined in heat treated (80 °C for 30 min) and sterilized cow's and ewe's milk. Ewe's milk enhanced growth of the streptococci, with significantly (P< 0·001) shorter generation times and higher acid production after 6 h incubation than cow's milk, probably due to its higher vitamin content. The stronger buffer capacity of ewe's milk allowed a higher (P< 0·001) acid production after 24 h than cow's milk. A stimulatory effect of sterilization on generation time and acid production after 24 h was observed in cow's milk. However, the heat treated ewe's milk was shown to be a better substrate than sterilized ewe's milk forStr. lactis.

Preparation of a highly active form of nisin from Streptococcus lactis

1971 ◽  
Vol 17 (1) ◽  
pp. 61-67 ◽  
Author(s):  
F. J. Bailey ◽  
A. Hurst
Keyword(s):  
Active Form ◽  
Gradient Elution ◽  
Antibiotic Activity ◽  
Complex Medium ◽  
Main Peak ◽  
Acetone Precipitation ◽  
Highly Active ◽  
Streptococcus Lactis ◽  
Constant Ph ◽  
Ph Gradient Elution

Cells of Streptococcus lactis (354/07) synthesized and retained nisin when grown in a complex medium with 2.5% glucose at a constant pH of 6.7. Nisin was extracted from cells by a previously used method with hot 0.05 N HCl but milder methods of extraction from whole and broken cells using a variety of solvents were also tested. In the preferred method broken cells were extracted with 0.05 N HCl at 2 °C. The Cl− ions of the extract were exchanged for acetate on columns of the resin Amberlite CG 4B and the eluate was concentrated by acetone precipitation at −19 °C. The nisin was finally purified by pH gradient elution from CM cellulose columns. Three peaks with antibiotic activity were found, two of the peaks were minor and represented less than 5% of the nisin. The main peak gave a single band on electrophoresis. Electrophoresis of the material from the CM cellulose peaks revealed about 44 bands of basic proteins. Nisin made by the hot or cold HCl extraction behaved similarly in electrophoresis and CM cellulose chromatography but the antibiotic activity of the material isolated from the cold extract was nine times greater than that of the material isolated from the hot extract.

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