LIVER BROTH

Code: CM0077

a liquid medium, containing liver particles, for the examination of foods for saccharolytic or putrefactive mesophilic and thermophilic anaerobes

* Adjusted as required to meet performance standards

Directions
Suspend 64 grams in 1 litre of distilled water and soak for 15 minutes, with occasional stirring. Distribute into 18mm diameter tubes to a depth of 50mm so that the bottom of the tube is filled with liver particles. Agitate frequently during distribution to keep the liver tissue in suspension.

Sterilise by autoclaving for 20 minutes at 115° C. Inoculate when cool and then aseptically seal with a layer of sterile 2% Oxoid Agar No.3 (LP0013) solution.

Description
A liver infusion medium, containing liver particles, for the examination of foods for saccharolytic or putrefactive mesophilic and thermophilic anaerobes. Also recommended for the maintenance of aerobes and anaerobes in pure culture.

Technique
Gillespie in communication with Scarr¹ recommended Liver Broth for the examination of canners’ sugar for hydrogen swells caused by thermophilic anaerobes (Clostridium thermosaccharolyticum). A 20% w/v solution of the sugar is steamed for 30 minutes to destroy vegetative forms and inoculated into Liver Broth sealed with agar. The standard proposed was a maximum of 1 positive tube in six - with 20ml inocula incubated for 72 hours at 56°C.

This medium should be made up only when required for use. Storage of the reconstituted medium is not recommended because air may be absorbed and the re-steaming necessary for the restoration of anaerobic conditions darkens the medium. Liver broth is not an homogeneous medium; consisting of a layer of liver particles and a cloudy supernatant. Growth produces an obvious increase in turbidity and some organisms (e.g. Clostridium thermosaccharolyticum) also produce gas which often pushes the agar plug towards the top of the tube. Some organisms also digest the solid liver tissue.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8° C.

Appearance
Dehydrated medium: Brown powder / granules
Prepared medium: Dark brown solution / particles

Quality Control

Precautions
Note the comments on storage and reheating.

Reference
1. Scarr M. Pamela (1958) DSIR, Proc. 2nd Internat. Symp. Food Microbiol. 1957, HMSO London, pp. 29-33.

ATCC^® is a registered trademark of American Type Culture Collection