BacterTube™ Half-Fraiser Broth

The medium used for selective enrichment and differentiation (primary enrichment broth) of Listeria monocytogenes and Listeria spp.
Code: 08045
Packaging: 50 tubes/ box or as per customer request.
Storage Conditions: 2–8°C.
Transportation: Ambient temperature.
Shelf Life: 6 months from the date of manufacture.

INTENDED USE

BacterTube™ Half-Fraiser Broth The Half Fraser broth is used for selective primary enrichment and detection of Listeria sp. in food and environmental samples.

PRINCIPLES

BacterTube™ Half-Fraiser Broth is a recovery medium for Listeria monocytogenes, ensured by the difference in the concentrations of nalidixic acid and acriflavine between Half-Fraser and Fraser, as well as the two-step enrichment process for Listeria monocytogenes. Half Fraser serves as the primary enrichment step, while Fraser Broth is used as the secondary enrichment step.
Polypeptone, yeast extract, and meat extract provide the essential nutrients for the growth of Listeria. The high concentration of sodium chloride increases the selectivity of the medium. Phosphates act as a buffer to maintain the pH of the medium. Esculin is hydrolyzed by Listeria into glucose and esculetin, and the latter forms a black complex with ferric ions from ferric citrate, which is added just before use to support the growth of Listeria. Lithium chloride inhibits the growth of most enterococci that hydrolyze esculin. Nalidixic acid prevents DNA replication in bacteria sensitive to this antimicrobial agent. Additionally, Gram-positive bacteria are inhibited by acriflavine.

Prior to inoculation, allow medium to equilibrate to room temperature
Use a sterile inoculation loop to transfer a sample from an isolated colony on the agar plate into the test tube containing the medium.
Incubate the tube at 30 ± 1°C.
Examine the tube after 24 – 26 hours of incubation.
Observe and record the results

RESULTS

After incubating for the required time, typically 24 – 26 hours, observe the colony growth within the medium.
To identify the isolated bacteria, further appropriate tests must be performed

BacterLab ensures the quality of each product batch by testing with ATCC reference strains.

Reference strains	Incubation conditions	Expected results
Listeria monocytogenes 4b ATCC 13932 · Enterococcus faecalis ATCC 19433 · Escherichia coli ATCC 25922	18 – 24 hours, 35 – 37^oC	Good growth
Listeria monocytogenes 1/2a ATCC 35152 · Enterococcus faecalis ATCC 19433 · Escherichia coli ATCC 29522		Good growth
Enterococccus faecalis ATCC 19433 Escherichia coli ATCC 25922		Inhibition

For 1 liter of medium