Conductimetric Analyses of Bacteriophage Infection of Two Groups of Bacteria in DL-Lactococcal Starter Cultures

Two conductimetric methods were used for simple and rapid detection of bacteriophages against the two major groups of bacteria in DL-lactococcal, mixed-strain starter cultures. Bacteriophages against the acid-producing bacteria Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris in a...

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Bibliographic Details
Published in:Journal of dairy science 1994-12, Vol.77 (12), p.3524-3531
Main Author: Svensson, Ulla K.
Format: Article
Language:English
Subjects:
BACTERIOFAGOS
BACTERIOPHAGE
bacteriophage analysis
Biological and medical sciences
conductance
CONDUCTIVIDAD ELECTRICA
CONDUCTIVITE ELECTRIQUE
CULTIVOS INICIADORES
CULTURE STARTER
DIOXIDO DE CARBONO
DIOXYDE DE CARBONE
Food industries
Fundamental and applied biological sciences. Psychology
indirect conductance method
INFECCION
INFECTION
LACTOCOCCUS LACTIS
LACTOSERUM
MEDIO DE CULTIVO
MILIEU DE CULTURE
Milk and cheese industries. Ice creams
starter culture activity
SUERO DE LA LECHE
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Summary:Two conductimetric methods were used for simple and rapid detection of bacteriophages against the two major groups of bacteria in DL-lactococcal, mixed-strain starter cultures. Bacteriophages against the acid-producing bacteria Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris in a starter were analyzed in a Malthus® instrument using reconstituted skim milk as the medium. The presence of phages against Lactococcus lactis ssp. lactis biovar. diacetylactis strains in a starter could be analyzed by measurement of CO2 production with an indirect conductance method in the Rabit® instrument. For both methods, the presence of phages against bacteria in a starter increased the detection time. At 30°C and .1% inoculum, a very sensitive assay was obtained that detected phages against acid-producing strains in a starter within 3 to 4h. The presence of 40 to 1000 infectious phages was sufficient for detection with a mixed-strain starter culture. Bacteriophages against CO2- producing bacteria were detected after 7 to 9h with a .1% inoculum at 30°C. Bacteriophage infection of single strains of bacteria reduced total change in conductance. For pure strains of an acid- or a CO2-producing strain, the detection limits were 1 and 100 pfu, respectively.
ISSN:0022-0302
1525-3198
DOI:10.3168/jds.S0022-0302(94)77294-5