LS5003 – Half Fraser Broth Selective Supplement

//LS5003 – Half Fraser Broth Selective Supplement

LS5003 – Half Fraser Broth Selective Supplement

Half Fraser Broth Selective Supplement
E&O Laboratories Ltd Half Fraser Selective Supplement (LS5003) is selective supplement for the primary enrichment of Listeria spp from food and environmental samples when used with Fraser Broth.Fraser Broth is a modification of the USDA-FSIS (United States Department of Agriculture-Food Safety Inspection Service) UVM secondary enrichment broth and is based on the formula described by Fraser and Sperber. It contains ferric ammonium citrate and
lithium chloride. Blackening of the medium is presumptive evidence of the presence of Listeria. Contrary to early indications, cultures which do not blacken cannot be assumed to be Listeria-free. All Fraser Broth enrichment cultures should be subcultured to plating medium. Fraser Broth has proven to be remarkably accurate in
detecting Listeria spp. in food and environmental samples.
All Listeria spp. hydrolyse aesculin to aesculetin. Aesculetin reacts with ferric ions which results in blackening. Another possible advantage to the addition of ferric ammonium citrate is that it has been shown that ferric ions enhance the growth of Listeria monocytogenes. Lithium chloride is included in the medium to inhibit the growth of enterococci which can also hydrolyse aesculin.
Half Fraser Broth is a modification of Fraser Broth which contains half of the concentration of nalidixic acid and acriflavine hydrochloride to aid in the recovery of stressed cells. Half Fraser Broth is used as the primary enrichment broth in the ISO methodology for the
detection of Listeria.

SKU: LS5003 Category:

Additional Information

Shelf Life (days)

Storage Temp (°C)

Dehydrated Medium Appearance

Dehydrated Medium Colour

PH

Solubility Description

Product Description

Organisms Ref. No Result
Listeria monocytogenes NCTC 11994 Growth & Black colonies
Escherichia coli NCTC 12241 Inhibited
Enterococcus faecalis NCTC 12697 Inhibited
Listeria innocua NCTC 11288 Growth & Black colonies

 

Formula

Vial Contents per Vial per Litre
Ferric ammonium citrate 112.5mg 500mg
Nalidixic acid 2.25mg 10.0mg
Acriflavine hydrochloride 2.82mg 12.5mg

Procedure

Suspend the recommended manufacturer’s amount of dehydrated media in 225ml of distilled water and mix well to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes. Cool to 45 – 50°C, and aseptically add the contents of one vial of Half Fraser Selective Supplement (LS5003).
To reconstitute vial add 3 mls of distilled water and mix before
addition to dehydrated media.